Evaluating Lower-Extremity Deep Vein Thrombosis using 3-Dimensional MR Black-Blood Thrombus Imaging: A Comparative Pilot Study

Evaluating Lower-Extremity Deep Vein Thrombosis using 3-Dimensional MR Black-Blood Thrombus Imaging: A Comparative Pilot Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluating Lower-Extremity Deep Vein Thrombosis using 3-Dimensional MR Black-Blood Thrombus Imaging: A Comparative Pilot Study Xinyu Wang, Congrui Sun, Yichen Tang, Yuehong Liu, Chen Zhang, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6287435/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objectives: This study aimed to evaluate the diagnostic performance of non-contrast magnetic resonance black-blood thrombus imaging (MRBTI) in detecting lower-extremity deep vein thrombosis (DVT) in comparison with computed tomography venography (CTV) and ultrasound (US). Methods: A total of 76 patients with consecutive lower-extremity DVT from March 2023 to February 2024 were included in this prospective study. All patients underwent MRBTI, CTV, and US. The image quality score and diagnostic confidence for MRBTI were determined by 2 readers independently using a 4-point scale. The sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive values (PPV and NPV, respectively) of MRBTI and CTV were calculated, using the values for US as the standard of reference. The thrombus signal intensity, signal intensity ratio (SIR), and clot burden were obtained in each thrombus segment, and interobserver agreement was calculated using the interclass correlation coefficient (ICC) and Cohen kappa coefficients (κ). Results: The interobserver agreement was excellent for readers 1 and 2 in grading the quality score and diagnostic confidence level of the images (3.78 ± 0.48 vs 3.77 ± 0.49, κ = 0.821, p < 0.001; 3.94 ± 0.25 vs 3.93 ± 0.28, κ = 0.872, p < 0.001, respectively). Using the values for US as the standard, the SE, SP, PPV, NPV, and ACC of MRBTI were 90.08%, 98.54%, 94.78%, 97.12%, and 96.62% for reader 1 and 90.67%, 98.11%, 93.39%, 97.27%, and 96.42% for reader 2. Both readers strongly agreed on SIR measurements（ICC: 0.974, 95% CI: 0.968-0.979, p < 0.001）and had good agreement on clot burden （k = 0.866, p < 0.001）. Conclusions: Noncontrast-enhanced MRBTI accurately detected lower-extremity DVT and robustly quantified the entire lower-extremity thrombus signal, enabling pretreatment evaluation of deep veins in patients with DVT. Registry: Chinese Clinical Trial Registry Trial registration number: ChiCTR2500099260 (retrospectively registered) Registration Date: 2025-03-20 (retrospectively registered) magnetic resonance black-blood thrombus imaging computed tomography deep vein thrombosis magnetic resonance imaging ultrasound Figures Figure 1 Figure 2 Figure 3 Introduction Accurate detection of deep vein thrombosis (DVT) is essential for preventing thrombus progression and maintaining quality of life [ 1 ]. DVT typically originates in the calf veins, potentially extending to proximal veins and migrating into the pulmonary circulation, leading to fatal pulmonary embolism (PE) [ 2 ]. Acute proximal DVT can be symptomatic or asymptomatic, with up to half of the patients developing post-thrombotic syndrome (PTS), leading to poor prognosis [ 3 ]. A comprehensive evaluation of venous thrombosis is crucial for determining the thrombus age and burden, guiding appropriate treatment decisions. Ultrasound (US) is the first-line screening tool for DVT, which is less sensitive to thrombi in pelvic and calf muscle veins [ 4 , 5 ]. Experience of the operator can greatly affect the accuracy of US, which is more challenging in obese and pregnant patients [ 6 ]. Computed tomography venography (CTV) complements US by detecting deep abdominopelvic venous thrombi for a more complete evaluation [ 7 , 8 ]. However, CTV has limitations, including suboptimal venous opacification and the potential for kidney damage due to the use of contrast agents [ 9 – 11 ]. Magnetic resonance black-blood thrombus imaging (MRBTI) is a novel non-contrast imaging technique. It allows direct visualization of the vessel wall and intraluminal thrombi [ 12 , 13 ]. Using delay alternating with nutation for tailored excitation–sampling perfection with application-optimized contrasts using various flip angle evolutions (DANTE-SPACE) sequence [ 14 ], this technique has an excellent flow suppression effect. Based on the difference in methemoglobin concentration in the thrombus, MRBTI can help distinguish the components and thrombus age by demonstrating various signal intensities with submillimeter resolution [ 15 , 16 ]. This study aimed to prospectively evaluate the detection rate of DVT using MRBTI compared with CTV using US as the reference standard and to determine its reliability in evaluating thrombus signal and burden. Materials and Methods Study design This prospective study was approved by the hospital institutional review board, and informed consent was obtained from all patients. From March 2024 to February 2025, 76 patients suspected of lower-extremity DVT were consecutively included in the study. The inclusion criteria were age > 18 years and definite evidence of DVT on US. The exclusion criteria were as follows: (1) contraindications to magnetic resonance imaging (MRI) and computed tomography (CT); (2) allergy to contrast agents, impaired renal function (glomerular filtration rate < 30 mL/min); (3) an interval of more than 48 hours between the CTV, MRBTI, and US examinations; and (4) any surgical procedure before the MRI scan. All patients underwent computed tomography pulmonary angiography (CTPA) combined with CTV, MRBTI, and US examinations. The patient’s comorbidities, and medical history were recorded and analyzed. The symptom duration (between symptom onset and admission) was also recorded at admission. MRI examinations All MRI scans were performed on a 3.0T magnetic resonance (MR) scanner (MAGNETOM Vida; Siemens Healthineers AG, Erlangen, Germany) using 2 8-channel body coils. Each patient was placed in the supine position (feet first), and 3-station MR scans were performed. The first station was from the common iliac vein to the proximal femoral vein, the second station was from the femoral vein to the proximal popliteal vein, and the third station covered the popliteal vein to the distal calf vein. The MRBTI protocol without contrast was performed for all patients, using the SPACE research sequence with DANTE blood suppression. The following scan parameters were used: repetition time = 700 milliseconds; echo time = 11 milliseconds; field-of-view (FOV) read = 400 mm; FOV phase = 100%; slices per slab = 256; voxel size = 0.6 × 0.6 × 0.7 mm 3 ; blood suppression = DANTE; fat suppression = water excitation; acceleration mode = generalized autocalibrating partially parallel acquisition; acceleration factor = 4; bandwidth = 1184 Hz/pixel; number of pulses = 200; DANTE gradient duration = 1 millisecond; gradient amplitude = 17 mT/m; and DANTE radiofrequency pulse flip angle = 15°. The scan time for each station was 4 minutes, and the total scan time was 12 minutes. CT examinations All patients were examined using a CT scanner (SOMATOM Force; Siemens Healthineers, Forchheim, Germany). CTPA was performed using dual-source single energy in the helical scan mode (pitch: 2.5). The parameters of the CTPA were as follows: tube voltage = 120 kV; reference tube current = 120 mAs; pitch = 1.9; rotation time = 0.25; and detector collimator = 192 × 0.6 mm 2 . These images were reconstructed with a slice thickness and interval thickness of 4 mm with kernel Br59. The parameters for CTV were as follows: tube voltage = 120 kV; reference tube current = 70 mAs; pitch = 0.8; rotation time = 0.25 s; and detector collimator = 192 × 0.6 mm 2 . These images were reconstructed with a slice thickness and interval thickness of 3 mm with kernel Bv36. All CTV images were reconstructed in axial, coronal, and sagittal orientations. A total dose of 50 mL of iohexol (iodine concentration: 320 mg/mL) was injected through the antecubital vein at a rate of 4.5 mL/s. Subsequently, the patient received a second contrast agent injection of 40 mL of iohexol at a rate of 2.5 mL/s, followed by a normal saline injection of 30 mL at a rate of 2.5 mL/s. Image analysis The images were reviewed randomly by 2 experienced radiologists, each with more than 10 years of experience. They were blinded to the clinical information and conducted their reviews independently. Image analyses of MRBTI and CTV were conducted independently with a time interval of 2 weeks for the absence or presence of DVT (yes/no) in the vessel segments of both sides. A total of 10 groups of venous segments were included in the image analysis: for the above/around-knee deep vein network segments: popliteal vein, superficial femoral vein, deep femoral vein, common femoral vein, and external iliac vein; for the below-knee deep vein network segments: gastrocnemius vein, soleus vein, anterior tibial vein, posterior tibial vein, and fibular vein. Based on consensus, proximal DVT was defined as involvement of above/around-knee with or without below-knee veins, and distal DVT was defined as involvement of below-knee veins without above/around-knee veins. Two independent readers scored the aforementioned 10 named venous segments for quality using a 4-point scale defined as follows: grade 4 = excellent visibility, no relevant artifacts; grade 3 = good visibility, minimal inhomogeneity, only minor flow artifacts; grade 2 = moderate visibility, delineated lumen, major flow artifacts; and grade 1 = indicating poor visibility, insufficient for diagnosis. The diagnostic confidence was also evaluated on a 4-point scale: 4 = excellent, exact diagnosis possible; 3 = good, definite diagnosis possible; 2 = fair, evaluation of major findings possible; and 1 = poor, definite diagnosis impossible. The diagnostic confidence score was used to rate the confidence of a reader in diagnosing the thrombus, whether it was present or not. The 2 readers independently delineated a circular region of interest (ROI) in the midpiece of the thrombus to measure the mean signal intensity (SI thrombus ), and the mean signal intensity of adjacent muscle (SI muscle ) was delineated at the corresponding slice. The ROI size ranged from 20 to 35 mm². The signal intensity ratio (SIR) was calculated as SI muscle /SI thrombus . Simultaneously, the clot burden of each segment was scored by the radiologists independently: 0, patent vein segment; 1, nonocclusive thrombus; 2, subsegmental, occlusive thrombus; and 3, occlusive thrombus of the entire length of a segment. Statistical analysis Statistical analyses were performed using SPSS version 27 (IBM Corp., NY, USA). Normally distributed continuous variables were presented as mean ± standard deviation, and asymmetrically distributed continuous variables were presented as median and interquartile range. The categorical variables were presented as counts (percentages). The Wilcoxon rank-sum test was used for continuous variables, and the chi-square test or Fisher’s exact test was used for categorical variables. The sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV, respectively), and accuracy were calculated. Interobserver agreement and agreement between standard US and MRBTI were tested using Cohen’s kappa test. The interobserver agreement for the image quality score was also determined using Cohen’s kappa test. The κ value was interpreted as follows: fair (κ = 0.21–0.40), moderate (κ = 0.41–0.60), substantial (κ = 0.61– 0.80), and excellent (κ > 0.80) [ 17 ]. The interclass correlation coefficient (ICC) with a 95% confidence interval (CI) using the 2-way random effects model was performed to test the interobserver agreements for thrombus signal intensity. The ICC was interpreted as follows: <0.40 as poor, 0.40–0.59 as fair, 0.60–0.74 as good, and ≥ 0.75 as excellent [ 18 ]. A 2-tailed p value of < 0.05 was considered statistically significant. Results Baseline characteristics of the patient s The baseline characteristics of patients are summarized in Table 1. In this study, 76 patients with DVT [51 (67%) in the proximal DVT group and 25 (33%) in the distal DVT group] were finally enrolled. Hypertension was the most common comorbidity in the 2 groups (43.14%, 36%), and immobility was the leading risk factor for all patients (46.05%). Of the 76 patients included, 13.16% had a history of venous thromboembolism (VTE). The mean symptom duration of patients with proximal DVT was 5.88 ± 2.86 days and that of distal DVT was 6.84 ± 3.29 days ( p =0.192). Image quality and diagnostic confidence of MRBTI The image quality of MRBTI is summarized in Table 2. In total, 1520 segments, 152 limbs, and 76 patients were evaluated. The average image quality score for 1520 venous segments for readers 1 and 2 were 3.78 ± 0.48 and 3.77 ± 0.49, respectively. The interobserver agreement was excellent for readers 1 and 2 in grading the image quality (κ = 0.821, p < 0.001). Among the above/around-knee veins, venous visualization of 79.8% (reader 1, 607/760) and 80.4% (reader 2, 611/760) segments were rated as excellent. Among the below-knee veins, venous visualization of 80% (reader 1, 608/760) and 78.7% (reader 2, 598/760) segments were rated as excellent. The average image quality score for above/around-knee segments for readers 1 and 2 was 3.78 ± 0.45 and 3.79 ± 0.45, and that of below-knee segments was 3.77 ± 0.51 and 3.76 ± 0.52, respectively. Venous visualization of 12 of 1520 segments was determined to be poor (grade = 1). The reasons were motion artifacts ( n = 6), artifacts related to B1 inhomogeneity ( n = 5), and susceptibility artifacts from metallic intrauterine ring ( n = 1). The average diagnostic confidence for all segments for readers 1 and 2 was 3.94 ± 0.25 and 3.93 ± 0.28, respectively, and the interobserver agreement was excellent for overall diagnostic confidence (κ = 0.872, p <0.001). Diagnostic performance of MRBTI and CTV compared with US Table 3 shows the number of thrombus segments diagnosed using MRBTI, CTV, and US. Of 1508 assessable venous segments after ruling out 12 segments with poor visualization (grade = 1), DVT was identified in 346 segments using US (Table 3). Reader 1 identified DVT in 329 vessel segments and reader 2 in 314 vessel segments using MRBTI images. According to the consensus reading of CTV, a thrombus was detected in 319 of 1508 vessel segments. Image examples are presented in Figures 1–3. Table 4 shows the SE and SP of MRBTI in detecting lower-extremity DVT, with US serving as the reference standard. Both readers identified 5 thrombi in the above/around-knee venous segments that were “false positives”: 2 in the external iliac veins, 1 in the common femoral vein, and 2 in the deep femoral veins. Both readers further missed 3 thrombi (“false negatives”), respectively in the common femoral, deep femoral, and popliteal veins. In addition, reader 1 evaluated 12 false-positive segments in below-knee venous segments and missed 31 segments that were classified as thrombosed in US, and reader 2 evaluated 17 false-positive segments in below-knee venous segments and missed 29 thrombosed segments. For reader 1, the comparison of the MRBTI with the standard US resulted in an SE of 90.08%, an SP of 98.54%, a PPV of 94.78%, an NPV of 97.12%, and an accuracy of 96.62% (Table 4). The corresponding values for reader 2 were an SE of 90.67%, an SP of 98.11%, a PPV of 93.39%, an NPV of 97.27%, and an accuracy ACC of 96.42%. The inter-reader reproducibility for the presence or absence of DVT for the MRBTI images was strong (κ = 0.948, p < 0.001). A detailed overview of the diagnostic performance of MRBTI compared with US is summarized in Table 4. When CTV was compared with US, the readers correctly identified a thrombus in 249 of 346 vessel segments (71.96%): 141 proximal vessel segments (88.67%) and 108 distal vessel segments (57.75%). The comparison of the CTV with the US resulted in an SE of 94.04%, an SP of 71.97%, a PPV of 91.92%, an NPV of 78.06%, and an accuracy of 89.01%. Thrombus signal intensity and clot burden using MRBTI in lower-extremity DVT For readers 1 and 2, the average thrombus signal intensity of all segments was 226.18 ± 87.92 and 225.14 ± 86.90, and the SIR was 1.69 ± 0.54 and 1.70 ± 0.54, respectively (Table 5). For reader 1, the SIR of above/around-knee veins were 1.52 ± 0.51, and below-knee veins was 1.86 ± 0.51; for reader 2, the SIR of above/around-knee veins were 1.54 ± 0.50, and below-knee veins was 1.85 ± 0.53. The interobserver agreement was excellent for overall SIRs (ICC: 0.974, 95% CI: 0.968-0.979, p < 0.001). The venous clot burden score obtained using MRBTI ranged from 0 to 3, with an average of 0.49 ± 0.99 for reader 1 and 0.50 ± 0.99 for reader 2. The interobserver agreement for MRBTI in assessing clot burden was excellent (k = 0.866, p <0.001). Discussion This study addressed the clinical value of noncontrast-enhanced MRBTI for detecting and evaluating lower-extremity DVT. Our analysis demonstrated that this technique rapidly provided excellent venous visualization of the entire lower-extremity venous networks, and high SE and SP for detecting DVT compared with CTV and US. It allowed direct visualization of the lower limb and pelvic veins, providing reliable semi-quantitative parameters of thrombus signal intensity and clot burden. The 3-station MRBTI scans provide fast data acquisition, high spatial resolution, and a large FOV in the craniocaudal direction of the entire lower limb, ensuring stable image quality [ 19 ]. Using SPACE sequence, MRBTI allows a 3-dimensional scan to be completed in a reasonable time (approximately 4 minutes) [ 20 ]. Additionally, black-blood preparation using DANTE was introduced to achieve effective flow signal suppression, capable of suppressing the signal of flow at a velocity as low as 1 mm/s [ 21 ]. In this study, 5 venous segments were identified with poor image quality due to the nonuniformity of the main magnetic field (B0) and the radiofrequency field (B1) of the MRI. This inhomogeneity was often observed at the edges of each station, resulting in fat suppression failure artifacts [ 22 ]. Although water excitation was employed for improved fat suppression, complete artifact elimination was hindered by the large FOV required for lower limb imaging. Further research is needed to develop more effective solutions to address these image inconsistencies. The current study demonstrated that MRBTI had the potential to be a noninvasive technique for diagnosing and mapping pelvic and lower-extremity DVT. In the present study, MRBTI indicated a high SP for the overall detection of DVT (98.54% for reader 1 and 98.11% for reader 2). Among the above/around-knee venous segments, both the readers identified 5 false-positive segments: 2 external iliac veins, 1 common femoral vein, and 2 deep femoral veins. Compared with CTV images, these 5 segments were also evaluated as false positives, indicating the presence of a thrombus. The false positives may have resulted from the thrombus missed during the US examination or formed between the US and MR scans [ 23 ]. For the below-knee venous segments, the 2 readers detected 12 and 17 false-positive segments, reducing the SP to 97.87% and 96.95%, respectively. The slower blood flow in below-knee veins, which is impeded and aggravated by thrombosis, may contribute to insufficient suppression of blood flow signals, leading to these false positives [ 24 ]. Compared with DUS, the readers missed 3 false-negative segments in the above/around-knee vein segments using MRBTI, reducing the overall SE to 99.17%. Upon re-evaluation, iso-intense thrombi were observed in the common femoral and deep femoral veins, along with a small thrombus in the distal popliteal vein. For the below-knee vein segments, the SE of MRBTI for DVT detection was lower compared with that in the above/around-knee segments (83.15% and 84.23%, respectively), due to the thinner vein diameter and extensive branching [ 25 ]. A previous study demonstrated that the SE of US for detecting DVT varied based on the location of the thrombus, and it ranged from 94.2% for proximal to 63.5% for distal veins [ 26 ]. In contrast, MRBTI had a higher resolution and an improved definition of the vessel wall, improving the imaging of DVT. The signal intensity of the thrombus varies according to the onset time, and this heterogeneity could be visually observed using the MRBTI images. When coagulation and thrombus form, hemoglobin in the red blood cells undergoes a series of characteristic oxidative changes over time [ 27 , 28 ]. In the early stage, the peptide chain structure surrounding deoxyhemoglobin remains intact, which cannot produce a paramagnetic effect that shortens the T1 relaxation time, resulting in an equal signal intensity of thrombus [ 29 ]. During this period, a thrombus dominated by loosely structured deoxyhemoglobin is regarded as a newly formed “fresh” thrombus. Over time, iron within the thrombus is oxidized by inducible nitric oxide synthase, leading to the accumulation of paramagnetic Fe 3+ . The resulting methemoglobin-dominated thrombus exhibits high signal intensity, along with fibrin cross-linking and collagen deposition [ 30 , 31 ]. In this study, MRBTI provided stable and reproducible thrombus signal intensity that can intuitively reflect the thrombus period. For both reviewers, the SIR of the below-knee venous segment was higher than that of the above/around-knee venous segments, which was consistent with the natural evolution of thrombosis. Several studies have reported that DVT typically starts in the calf veins and extends to the proximal veins [ 32 , 33 ]. Distinguishing between new and chronic thrombi based on thrombus signal intensity on MRBTI is a promising clinical application of this technology. Unlike the CTV techniques, which indirectly identify thrombi through blood-filling defects, MRBTI allows the direct visualization of the thrombus and measurement of clot burden. The incidence of PTS is higher in patients with DVT with a considerable thrombus burden, and anticoagulation alone has limited effectiveness in such cases [ 34 ]. For patients with a high thrombus burden in the acute stage, more aggressive thrombus removal measures should be considered to reduce clot load, protect venous valve function, and lower the incidence of PTS [ 35 ]. In this study, MRBTI demonstrated excellent interobserver consistency in assessing clot burden, providing valuable quantitative information for DVT treatment decision-making. This study had certain limitations. First, the sample size was limited. However, 1520 venous segments were examined through MRBTI images and could be included in the thrombus detectability analysis. Second, this study used US as the reference standard rather than CTV. The SE of MRBTI may be erroneously reduced if US does not detect a clot really present. Contrast-enhanced magnetic resonance venography can be used as a reference standard, and MRBTI can be systematically evaluated in a further study. Third, a time interval exists between MRI and US examinations. The therapeutic doses of heparin were started immediately after the diagnosis of DVT. This biased the comparison of MRBTI and US in terms of thrombus detectability because a few thrombi may have been lysed. In conclusion, the MRBTI technology is highly accurate in detecting lower-extremity DVT with good to excellent SE and SP values. It provides a rapid, non-nephrotoxic method to evaluate the lower-extremity venous network and abdominopelvic veins in patients with DVT and can provide good image quality and reliable and stable thrombus signal values. Further prospective studies are needed to evaluate the diagnostic value of MRBTI in differentiating old from recurrent thrombi and its clinical benefit in providing a supplementary roadmap preoperatively. Abbreviations MRBTI, magnetic resonance black-blood thrombus imaging DVT, deep vein thrombosis DANTE, delay alternating with nutation for tailored excitation SPACE, sampling perfection with application-optimized contrasts using various flip angle evolutions PE, pulmonary embolism PTS, post-thrombotic syndrome SIR, signal intensity ratio ICC, interclass correlation coefficient Declarations Acknowledgements Not applicable. Author contributions Wang and Sun were responsible for conceptualization; Wang, Sun, Tang, and Liu were responsible for data analysis; Zhang, Zhang, Stemmer, and Xie were responsible for supervision; Wang and Sun wrote the manuscript; Wang, Sun, Yang and Li were responsible for the experimental design; Stemmer, Yang, and Li reviewed and edited the manuscript; Yang contributed to project management and funding acquisition. All authors have read and agreed to publish the manuscript. Funding This work was supported by grants from the Beijing Hospitals Authority Clinical Medicine Development of Special Funding Support (ZLRK202306), the National Natural Science Foundation of China (92249301), the Beijing Hospitals Authority’s Ascent Plan (DFL20220303), and the Beijing Key Specialists in Major Epidemic Prevention and Control. Data availability Data sharing is not applicable to this article as no datasets were generated or analysed during the current study. Ethics approval and consent to participate This study was conducted in accordance with the Declaration of Helsinki (as revised in 2013) and was approved by the Medical Ethics Committee of Beijing Chaoyang Hospital, Capital Medical University (ethical batch number: 2024 - KE - 25). All methods were carried out in accordance with relevant guidelines and regulations. Consent for publication Not applicable. Competing interests The authors of this manuscript declare relationships with the following companies: A.S. and C.Z. are employees of Siemens Healthineers. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References Di Nisio M, van Es N, Büller HR. Deep vein thrombosis and pulmonary embolism. Lancet. 2016;388(10063):3060–73. Khan F, Tritschler T, Kahn SR, Rodger MA. Venous thromboembolism. Lancet. 2021;398(10294):64–77. 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Fedullo PF, Rubin LJ, Kerr KM, Auger WR, Channick RN. The natural history of acute and chronic thromboembolic disease: the search for the missing link. Eur Respir J. 2000;15(3):435–7. Prandoni P, Kahn SR. Post-thrombotic syndrome: prevalence, prognostication and need for progress. Br J Haematol. 2009;145(3):286–95. Sartori M, Favaretto E, Cini M, Legnani C, Palareti G, Cosmi B. D-dimer, FVIII and thrombotic burden in the acute phase of deep vein thrombosis in relation to the risk of post-thrombotic syndrome. Thromb Res. 2014;134(2):320–5. Tables Table 1. Baseline characteristics of patients Variable Proximal DVT ( n = 51) Distal DVT ( n = 25) Total ( n = 76) P value Demographics Age, year 61.37 ± 14.33 60.56 ± 14.57 61.11 ± 14.32 0.817 Male sex, n (%) 28 (54.90) 12 (48.00) 40 (52.63) 0.748 Comorbidities Smoking, n (%) 12 (23.53) 5 (20.00) 17 (22.37) 0.957 Drinking, n (%) 11 (21.57) 3 (12.00) 14 (18.42) 0.486 Hypertension, n (%) 22 (43.14) 9 (36.00) 31 (40.79) 0.729 Diabetes, n (%) 7 (13.73) 2 (8.00) 9 (11.84) 0.728 Medical history Coronary artery disease, n (%) 8 (15.69) 3 (12.00) 11 (14.47) 0.935 Cerebrovascular accident, n (%) 11 (21.57) 3 (12.00) 14 (18.42) 0.486 Varicose veins, n (%) 6 (11.76) 4 (16.00) 10 (13.16) 0.879 Long bone fracture, n (%) 4 (7.84) 3 (12.00) 7 (9.21) 0.868 History of malignancy, n (%) 7 (13.73) 2 (8.00) 9 (11.84) 0.728 Major surgery, n (%) 13 (25.49) 4 (16.00) 17 (22.37) 0.522 Immobility, n (%) 25 (49.02) 7 (28.00) 35 (46.05) 0.135 Previous VTE, n (%) 7 (13.73) 3 (12.00) 10 (13.16) ＞.999 Mean symptom duration (day) 5.88 ± 2.86 6.84 ± 3.29 6.2 ± 2.31 0.192 Continuous data are presented as mean ± standard deviation, and categorical data are presented as count (percentage). VTE = venous thromboembolism. Table 2. Image quality of MRBTI as graded independently by 2 readers Image quality of vessel according to reader 1 Image quality of vessel according to reader 2 Segment Grade 1 Grade 2 Grade 3 Grade 4 Score* Grade 1 Grade 2 Grade 3 Grade 4 Score* Above/Around-knee External iliac vein 2 1 59 90 3.56 ± 0.58 2 1 63 86 3.53 ± 0.59 Common femoral vein 0 0 22 130 3.86 ± 0.35 0 0 20 132 3.87 ± 0.34 Deep femoral vein 0 0 11 141 3.93 ± 0.26 0 0 11 141 3.93 ± 0.26 Superficial femoral vein 0 3 36 113 3.72 ± 0.49 0 3 36 113 3.72 ± 0.49 Popliteal vein 1 1 17 133 3.86 ± 0.42 1 1 11 139 3.89 ± 0.38 Total 3 5 145 607 3.78 ± 0.45 3 5 141 611 3.79 ± 0.45 Below-knee Fibular vein 0 1 17 134 3.88 ± 0.35 1 1 11 139 3.89 ± 0.38 Anterior tibial veins 1 1 22 128 3.82 ± 0.45 1 1 25 125 3.80 ± 0.46 Posterior tibial veins 3 0 23 126 3.79 ± 0.54 2 0 33 117 3.74 ± 0.52 Gastrocnemius vein 3 0 41 108 3.67 ± 0.58 3 2 41 106 3.64 ± 0.61 Soleal vein 2 1 37 112 3.70 ± 0.55 2 2 37 111 3.69 ± 0.57 Total 9 3 140 608 3.77 ± 0.51 9 6 147 598 3.76 ± 0.52 Over all 12 8 285 1215 3.78 ± 0.48 12 11 288 1209 3.77 ± 0.49 * Values are mean ± standard deviation. Grade 1: poor visibility; grade 2: moderate visibility; grade 3: good visibility; and grade 4: excellent visibility. MRBTI, Magnetic resonance black-blood thrombus imaging. Table 3. Number of thrombus segments diagnosed using MRBTI, CTV, and US MRBTI CTV US Segment Reader 1/Reader 2 Above/Around-knee External iliac vein 30/30 29 28 Common femoral vein 30/30 29 30 Deep femoral vein 19/19 11 18 Superficial femoral vein 38/39 43 38 Popliteal vein 43/43 52 44 Total 161/161 166 159 Below-knee Fibular vein 38/36 43 39 Anterior tibial veins 28/29 30 28 Posterior tibial veins 31/37 36 41 Gastrocnemius vein 35/34 21 41 Soleal vein 35/38 22 36 Total 168/175 153 187 Overall 329/314 319 346 CTV, Computed tomography venography; MRBTI, magnetic resonance black-blood thrombus imaging; US, ultrasound. Table 4. Sensitivity and specificity of MRBTI in detecting lower-extremity DVT, with US serving as the reference standard Reader 1 Reader 2 Segment TP FP FN TN ACC (95% CI) SE (95%vCI) SP (95% CI) PPV (95% CI) NPV (95% CI) TP FP FN TN ACC (95% CI) SE (95%vCI) SP (95% CI) PPV (95% CI) NPV (95% CI) Above/Around-knee External iliac vein 28 2 0 120 98.67 (95.27-99.84) 98.36 (94.20-99.80) 100 (87.66-100.00) 100 (96.97-100.00) 93.33 (77.93-99.18) 28 2 0 120 98.67 (95.27-99.84) 98.36 (94.30-99.80) 100 (87.66-100.00) 100 (97.02-100.00) 93.33 (77.93-99.18) Common femoral vein 29 1 1 121 98.68 (95.33-99.84) 99.18 (95.52-99.98) 96.67 (82.78-99.92) 99.18 (95.52-99.98) 96.67 (82.78-99.92) 29 1 1 121 98.68 (95.33-99.84) 99.18 (95.52-99.98) 96.67 (82.78-99.92) 99.18 (95.52-99.98) 96.67 (82.78-99.92) Deep femoral vein 17 2 1 130 98.00 (94.34-99.59) 98.51 (94.71-99.82) 98.48 (93.81-99.86) 99.25 (95.88-99.98) 99.23 (95.86-99.97) 17 2 1 130 98.00 (94.34-99.59) 98.51 (94.71-99.82) 98.48 (93.81-99.86) 99.25 (95.88-99.98) 99.23 (95.86-99.97) Superficial femoral vein 39 0 0 113 100 (97.60-100.00) 100 (96.79-100.00) 100 (90.97-100.00) 100 (96.79-100.00) 100 (90.97-100.00) 39 0 0 113 100 (97.60-100.00) 100 (96.79-100.00) 100 (90.97-100.00) 100 (96.79-100.00) 100 (90.97-100.00) Popliteal vein 43 0 1 107 99.34 (96.37-99.98) 100 (96.61-100.00) 97.73 (87.98-99.94) 99.07 (94.95-99.98) 100 (91.78-100.00) 43 0 1 107 99.34 (96.37-99.98) 100 (96.61-100.00) 97.73 (87.98-99.94) 99.08 (94.99-99.98) 100 (91.78-100.00) Total 156 5 3 594 98.94 (97.94-99.54) 99.17 (98.07-99.73) 99.16 (95.49-99.96) 99.50 (98.54-99.90) 99.49 (95.91-99.98) 156 5 3 594 98.94 (97.94-99.54) 99.17 (98.07-99.73) 99.16 (95.49-99.96) 99.50 (98.54-99.90) 99.49 (95.91-99.98) Below-knee Fibular vein 36 2 3 111 96.71 (92.49-98.92) 98.23 (93.75-99.78) 92.31 (79.13-98.38) 97.37 (92.50-99.45) 94.74 (82.25-99.36) 35 1 4 111 96.69 (92.44-98.92) 99.11 (95.13-99.98) 89.74 (75.78-97.13) 96.52 (91.33-99.04) 97.22 (85.47-99.93) Anterior tibial veins 22 3 4 112 95.03 (90.68-98.12) 84.61 (65.27-95.49) 97.39 (87.34-99.11) 88.00 (91.88-99.11) 96.55 (83.14-99.74) 21 5 4 111 93.62 (88.99-96.54) 84.00 (78.10-89.12) 95.68 (90.43-98.84) 80.76 (66.72-91.23) 96.52 (82.23-99.15) Posterior tibial veins 30 1 10 108 92.62 (87.17-96.26) 99.08 (94.99-99.98) 75.00 (58.80-87.31) 91.53 (84.97-95.86) 96.77 (83.30-99.92) 33 4 8 105 92.00 (86.44-95.80) 96.33 (90.87-98.99) 80.49 (65.13-91.18) 92.92 (86.53-96.89) 89.19 (74.58-96.97) Gastrocnemius vein 32 3 9 105 91.95 (86.35-95.77) 97.22 (92.10-99.42) 78.05 (62.39-89.44) 92.11 (85.54-96.33) 91.43 (76.94-98.20) 32 2 9 106 92.62 (87.17-96.26) 98.15 (93.47-99.77) 78.05 (62.39-89.44) 92.17 (85.66-96.36) 94.12 (80.32-99.28) Soleal vein 32 3 4 111 95.33 (90.62-98.10) 97.37 (92.50-99.45) 88.89 (73.94-96.89) 96.52 (91.33-99.04) 91.43 (76.94-98.20) 33 5 3 109 94.67 (89.76-97.67) 95.61 (90.06-98.56) 91.67 (77.53-98.25) 97.32 (92.37-99.44) 86.84 (71.91-95.59) Total 153 12 31 554 94.26 (92.45-95.78) 83.15 (77.30-88.45) 97.87 (87.79-99.62) 92.72 (85.65-96.41) 94.70 (82.13-99.25) 155 17 29 542 93.81 (92.01-95.24) 84.23 (78.49-89.36) 96.95 (83.14-99.95) 90.12 (84.90-94.24) 94.92 (81.22-99.58) Overall 309 17 34 1148 96.62 (95.61-97.47) 90.08 (86.54-93.10) 98.54 (93.92-99.87) 94.78 (82.53-99.37) 97.12 (87.22-99.34) 311 22 32 1143 96.42 (95.39-97.30) 90.67 (85.12-94.87) 98.11 (97.18-98.82) 93.39 (90.25-95.85) 97.27 (96.21-98.14) ACC, Accuracy; DVT, deep vein thrombosis; FN, true-negative; FP, false-positive; MRBTI, magnetic resonance black-blood thrombus imaging; SE, sensitivity; SP, specificity; NPV, negative predictive values; PPV, positive predictive values; TN, true-negative; TP, true-positive; US, ultrasound. Table 5. Thrombus signal intensity and clot burden of MRBTI in lower-extremity DVT Reader 1 Reader 2 Segment Thrombus signal intensity Muscle signal intensity SIR Clot burden Thrombus signal intensity Muscle signal intensity SIR Clot burden Above/Around-knee External iliac vein 194.94 ± 94.80 136.37 ± 40.61 1.40 ± 0.45 0.48 ± 1.00 197.17 ± 94.89 136.19 ± 40.90 1.42 ± 0.47 0.47 ± 0.98 Common femoral vein 186.52 ± 70.28 135.29 ± 33.42 1.38 ± 0.41 0.52 ± 1.09 186.75 ± 68.89 133.48 ± 33.63 1.40 ± 0.41 0.53 ± 1.09 Deep femoral vein 202.65 ± 86.09 131.03 ± 33.41 1.58 ± 0.65 0.29 ± 0.81 201.88 ± 85.40 128.24 ± 33.67 1.59 ± 0.58 0.30 ± 0.83 Superficial femoral vein 198.87 ± 83.21 134.62 ± 39.63 1.49 ± 0.53 0.73 ± 1.27 199.41 ± 83.29 132.88 ± 39.76 1.52 ± 0.55 0.73 ± 1.27 Popliteal vein 221.83 ± 84.68 128.12 ± 31.17 1.72 ± 0.48 0.76 ± 1.25 219.44 ± 82.36 127.66 ± 30.52 1.70 ± 0.47 0.74 ± 1.23 Total 202.42 ± 83.93 132.92 ± 35.59 1.52 ± 0.51 0.56 ± 1.11 202.16 ± 82.97 131.61 ± 35.62 1.54 ± 0.50 0.55 ± 1.09 Below-knee Fibular vein 241.25 ± 99.54 134.48 ± 32.42 1.79 ± 0.60 0.52 ± 0.96 243.17 ± 96.89 135.27 ± 31.53 1.81 ± 0.62 0.50 ± 0.95 Anterior tibial veins 243.17 ± 81.50 139.75 ± 33.89 1.76 ± 0.50 0.32 ± 0.73 245.93 ± 74.96 139.45 ± 30.99 1.78 ± 0.46 0.34 ± 0.75 Posterior tibial veins 241.12 ± 75.16 130.77 ± 34.30 1.88 ± 0.51 0.39 ± 0.82 227.20 ± 83.81 129.05 ± 38.72 1.79 ± 0.55 0.52 ± 0.93 Gastrocnemius vein 258.23 ± 95.25 139.56 ± 31.41 1.84 ± 0.51 0.48 ± 0.89 262.96 ± 90.01 140.26 ± 30.53 1.87 ± 0.50 0.45 ± 0.83 Soleal vein 258.65 ± 74.16 130.58 ± 32.90 2.01 ± 0.43 0.41 ± 0.80 252.38 ± 77.63 129.00 ± 34.29 2.00 ± 0.48 0.45 ± 0.84 Total 248.81 ± 85.87 134.95 ± 32.75 1.86 ± 0.51 0.42 ± 0.85 246.27 ± 85.28 134.35 ± 33.42 1.85 ± 0.53 0.45 ± 0.87 Overall 226.18 ± 87.92 133.96 ± 34.13 1.69 ± 0.54 0.49 ± 0.99 225.14 ± 86.90 133.04 ± 34.47 1.70 ± 0.54 0.50 ± 0.99 DVT, Deep vein thrombosis; MRBTI, magnetic resonance black-blood thrombus imaging; SIR, signal intensity ratio. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6287435","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":444094338,"identity":"141945f2-8a0f-4ca2-b31d-7cdae9fcf606","order_by":0,"name":"Xinyu Wang","email":"","orcid":"","institution":"Beijing Chao-Yang Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xinyu","middleName":"","lastName":"Wang","suffix":""},{"id":444094339,"identity":"7d380969-b844-4340-a0f5-c57b1d29a7e4","order_by":1,"name":"Congrui Sun","email":"","orcid":"","institution":"Beijing Chao-Yang Hospital","correspondingAuthor":false,"prefix":"","firstName":"Congrui","middleName":"","lastName":"Sun","suffix":""},{"id":444094340,"identity":"d4949ab9-8f85-47bd-9624-cac4de0353b9","order_by":2,"name":"Yichen Tang","email":"","orcid":"","institution":"Beijing Chao-Yang Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yichen","middleName":"","lastName":"Tang","suffix":""},{"id":444094341,"identity":"99c5f6e8-4a9f-4276-9282-bc4c2f9fadbb","order_by":3,"name":"Yuehong Liu","email":"","orcid":"","institution":"Beijing Chao-Yang Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yuehong","middleName":"","lastName":"Liu","suffix":""},{"id":444094342,"identity":"d24dba64-88d6-410f-af24-d31839498f9e","order_by":4,"name":"Chen Zhang","email":"","orcid":"","institution":"MR Research Collaboration, Siemens Healthineers","correspondingAuthor":false,"prefix":"","firstName":"Chen","middleName":"","lastName":"Zhang","suffix":""},{"id":444094343,"identity":"4b008758-073f-4cbb-8029-8c32c8b82299","order_by":5,"name":"Jiajia Zhang","email":"","orcid":"","institution":"Beijing Chao-Yang Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jiajia","middleName":"","lastName":"Zhang","suffix":""},{"id":444094344,"identity":"6ebe954f-4ef7-49a2-856a-73e5ae32920e","order_by":6,"name":"Alto Stemmer","email":"","orcid":"","institution":"Siemens Healthineers AG","correspondingAuthor":false,"prefix":"","firstName":"Alto","middleName":"","lastName":"Stemmer","suffix":""},{"id":444094345,"identity":"251c36c1-e1b4-4b00-ad91-7fc60fd17867","order_by":7,"name":"Guoxi Xie","email":"","orcid":"","institution":"Guangzhou Medical University","correspondingAuthor":false,"prefix":"","firstName":"Guoxi","middleName":"","lastName":"Xie","suffix":""},{"id":444094346,"identity":"3874b1d0-46b5-4f2b-96ac-39903857f23d","order_by":8,"name":"Chunmin Li","email":"","orcid":"","institution":"Beijing Chao-Yang Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chunmin","middleName":"","lastName":"Li","suffix":""},{"id":444094347,"identity":"59f9939e-e9d4-4ae1-b0dc-387449a6e974","order_by":9,"name":"Qi Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/ElEQVRIiWNgGAWjYFADZgaGAx+ANBs7KVoOzgBpYSbJIh6oXrzA4PjZw695au7Y9R1n3njY5tc2eT5mBsYPH3PwaDmTl2bNc+xZ8szDbAWHc/tuG7YxMzBLztyGR8uBHDNjHrbDyQaHeQwO5/bcZgRqYWPmxafl/Bugln9QLZY9t+0Ja7mRY/yYt+2wHVgLw4/biQS1SN54Y8Y4t+9wgiTQLwd7G24ntzEzNuP1C9/5HOMPb74dtuc7f3jzhx9/btvOb28++OEjHi0KBxjYpIDRkdhwgMGAgbENJMbYgFs9EMg3MDB//MHAYM8A0sLwB6/iUTAKRsEoGKEAABGCWgQoaiY6AAAAAElFTkSuQmCC","orcid":"","institution":"Beijing Chao-Yang Hospital","correspondingAuthor":true,"prefix":"","firstName":"Qi","middleName":"","lastName":"Yang","suffix":""}],"badges":[],"createdAt":"2025-03-23 09:23:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6287435/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6287435/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82135766,"identity":"bddeda0b-336d-4388-86fa-7ca066b31f5e","added_by":"auto","created_at":"2025-05-07 06:09:38","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":406879,"visible":true,"origin":"","legend":"\u003cp\u003eMRBTI, CTV and ultrasound images of a patient with distal DVT.\u003cstrong\u003e \u003c/strong\u003e(A) MRBTI image of distal DVT patient. (B) The coronal image of MRBTI in 3 slices. Normal veins appear as black lumens after blood suppression (the first figure in the second column, indicated by a red arrow). The hyper-intense thrombus was observed in gastrocnemius vein and soleal vein (the second and third figure in the second column, indicated by a red arrow). (C) In the CTV images, the thrombus was difficult to identify in the aforementioned segments. (D) Flow was absent within these segments in ultrasound. CTV, Computed tomography venography; DVT, deep vein thrombosis; MRBTI, magnetic resonance black-blood thrombus imaging.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6287435/v1/e23fdd1b21743a27f537e074.png"},{"id":82137286,"identity":"9f5b56f7-f20b-44b1-9754-0493e08c9ae0","added_by":"auto","created_at":"2025-05-07 06:17:38","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":600714,"visible":true,"origin":"","legend":"\u003cp\u003eMRBTI, CTV and ultrasound images of a patient with proximal DVT.\u003cstrong\u003e \u003c/strong\u003e(A) In coronal MRBTI images, external iliac vein thrombus could be clearly visualized. The proximal segment of the thrombus demonstrated hyper-intense signal. (B) Additionally, MR could clearly display eccentric mural thrombi in the axial images. (C) CTV images are difficult to accurately identify filling defects and normal veins. (D) Flow was absent within these segments in ultrasound. CTV, computed tomography; MR, magnetic resonance.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6287435/v1/4968832501ddd69cab14a9db.png"},{"id":82135772,"identity":"dfe80504-1baa-4f4f-ba77-57f5eff53db3","added_by":"auto","created_at":"2025-05-07 06:09:38","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":545248,"visible":true,"origin":"","legend":"\u003cp\u003eTypical image of heterogeneous thrombus signal at different levels in a patient with proximal DVT.\u003cstrong\u003e \u003c/strong\u003e(A) Curved images of proximal DVT patient. Thrombus was noted in femoral, popliteal, fibular, and posterior tibial veins covered by 3 stations. (B) Coronal image of MRBTI. The iso-intense thrombus was observed in the proximal segments of superficial femoral vein, and the distal segments of superficial femoral vein and other parts of the thrombus appeared as hyper-intense signals. (C) Filling defects in superficial femoral vein as demonstrated in the CTV images, but the distal vein was difficult to identify by CTV. (D) Flow was absent within these segments in ultrasound. CTV, Computed tomography venography; DVT, deep vein thrombosis; MRBTI, magnetic resonance black-blood thrombus imaging.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6287435/v1/28a20729acee1dc4ada47057.png"},{"id":89484865,"identity":"b5e6043c-6a00-4e38-bc87-745fb51c9fa1","added_by":"auto","created_at":"2025-08-20 12:38:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3101964,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6287435/v1/a989767e-bba8-41da-87f7-204062c1e603.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluating Lower-Extremity Deep Vein Thrombosis using 3-Dimensional MR Black-Blood Thrombus Imaging: A Comparative Pilot Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAccurate detection of deep vein thrombosis (DVT) is essential for preventing thrombus progression and maintaining quality of life [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. DVT typically originates in the calf veins, potentially extending to proximal veins and migrating into the pulmonary circulation, leading to fatal pulmonary embolism (PE) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Acute proximal DVT can be symptomatic or asymptomatic, with up to half of the patients developing post-thrombotic syndrome (PTS), leading to poor prognosis [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. A comprehensive evaluation of venous thrombosis is crucial for determining the thrombus age and burden, guiding appropriate treatment decisions.\u003c/p\u003e \u003cp\u003eUltrasound (US) is the first-line screening tool for DVT, which is less sensitive to thrombi in pelvic and calf muscle veins [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Experience of the operator can greatly affect the accuracy of US, which is more challenging in obese and pregnant patients [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Computed tomography venography (CTV) complements US by detecting deep abdominopelvic venous thrombi for a more complete evaluation [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, CTV has limitations, including suboptimal venous opacification and the potential for kidney damage due to the use of contrast agents [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMagnetic resonance black-blood thrombus imaging (MRBTI) is a novel non-contrast imaging technique. It allows direct visualization of the vessel wall and intraluminal thrombi [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Using delay alternating with nutation for tailored excitation\u0026ndash;sampling perfection with application-optimized contrasts using various flip angle evolutions (DANTE-SPACE) sequence [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], this technique has an excellent flow suppression effect. Based on the difference in methemoglobin concentration in the thrombus, MRBTI can help distinguish the components and thrombus age by demonstrating various signal intensities with submillimeter resolution [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This study aimed to prospectively evaluate the detection rate of DVT using MRBTI compared with CTV using US as the reference standard and to determine its reliability in evaluating thrombus signal and burden.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design\u003c/h2\u003e \u003cp\u003eThis prospective study was approved by the hospital institutional review board, and informed consent was obtained from all patients. From March 2024 to February 2025, 76 patients suspected of lower-extremity DVT were consecutively included in the study. The inclusion criteria were age\u0026thinsp;\u0026gt;\u0026thinsp;18 years and definite evidence of DVT on US. The exclusion criteria were as follows: (1) contraindications to magnetic resonance imaging (MRI) and computed tomography (CT); (2) allergy to contrast agents, impaired renal function (glomerular filtration rate\u0026thinsp;\u0026lt;\u0026thinsp;30 mL/min); (3) an interval of more than 48 hours between the CTV, MRBTI, and US examinations; and (4) any surgical procedure before the MRI scan. All patients underwent computed tomography pulmonary angiography (CTPA) combined with CTV, MRBTI, and US examinations. The patient\u0026rsquo;s comorbidities, and medical history were recorded and analyzed. The symptom duration (between symptom onset and admission) was also recorded at admission.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMRI examinations\u003c/h3\u003e\n\u003cp\u003eAll MRI scans were performed on a 3.0T magnetic resonance (MR) scanner (MAGNETOM Vida; Siemens Healthineers AG, Erlangen, Germany) using 2 8-channel body coils. Each patient was placed in the supine position (feet first), and 3-station MR scans were performed. The first station was from the common iliac vein to the proximal femoral vein, the second station was from the femoral vein to the proximal popliteal vein, and the third station covered the popliteal vein to the distal calf vein. The MRBTI protocol without contrast was performed for all patients, using the SPACE research sequence with DANTE blood suppression. The following scan parameters were used: repetition time\u0026thinsp;=\u0026thinsp;700 milliseconds; echo time\u0026thinsp;=\u0026thinsp;11 milliseconds; field-of-view (FOV) read\u0026thinsp;=\u0026thinsp;400 mm; FOV phase\u0026thinsp;=\u0026thinsp;100%; slices per slab\u0026thinsp;=\u0026thinsp;256; voxel size\u0026thinsp;=\u0026thinsp;0.6 \u0026times; 0.6 \u0026times; 0.7 mm\u003csup\u003e3\u003c/sup\u003e; blood suppression\u0026thinsp;=\u0026thinsp;DANTE; fat suppression\u0026thinsp;=\u0026thinsp;water excitation; acceleration mode\u0026thinsp;=\u0026thinsp;generalized autocalibrating partially parallel acquisition; acceleration factor\u0026thinsp;=\u0026thinsp;4; bandwidth\u0026thinsp;=\u0026thinsp;1184 Hz/pixel; number of pulses\u0026thinsp;=\u0026thinsp;200; DANTE gradient duration\u0026thinsp;=\u0026thinsp;1 millisecond; gradient amplitude\u0026thinsp;=\u0026thinsp;17 mT/m; and DANTE radiofrequency pulse flip angle\u0026thinsp;=\u0026thinsp;15\u0026deg;. The scan time for each station was 4 minutes, and the total scan time was 12 minutes.\u003c/p\u003e\n\u003ch3\u003eCT examinations\u003c/h3\u003e\n\u003cp\u003eAll patients were examined using a CT scanner (SOMATOM Force; Siemens Healthineers, Forchheim, Germany). CTPA was performed using dual-source single energy in the helical scan mode (pitch: 2.5). The parameters of the CTPA were as follows: tube voltage\u0026thinsp;=\u0026thinsp;120 kV; reference tube current\u0026thinsp;=\u0026thinsp;120 mAs; pitch\u0026thinsp;=\u0026thinsp;1.9; rotation time\u0026thinsp;=\u0026thinsp;0.25; and detector collimator\u0026thinsp;=\u0026thinsp;192 \u0026times; 0.6 mm\u003csup\u003e2\u003c/sup\u003e. These images were reconstructed with a slice thickness and interval thickness of 4 mm with kernel Br59. The parameters for CTV were as follows: tube voltage\u0026thinsp;=\u0026thinsp;120 kV; reference tube current\u0026thinsp;=\u0026thinsp;70 mAs; pitch\u0026thinsp;=\u0026thinsp;0.8; rotation time\u0026thinsp;=\u0026thinsp;0.25 s; and detector collimator\u0026thinsp;=\u0026thinsp;192 \u0026times; 0.6 mm\u003csup\u003e2\u003c/sup\u003e. These images were reconstructed with a slice thickness and interval thickness of 3 mm with kernel Bv36. All CTV images were reconstructed in axial, coronal, and sagittal orientations.\u003c/p\u003e \u003cp\u003eA total dose of 50 mL of iohexol (iodine concentration: 320 mg/mL) was injected through the antecubital vein at a rate of 4.5 mL/s. Subsequently, the patient received a second contrast agent injection of 40 mL of iohexol at a rate of 2.5 mL/s, followed by a normal saline injection of 30 mL at a rate of 2.5 mL/s.\u003c/p\u003e\n\u003ch3\u003eImage analysis\u003c/h3\u003e\n\u003cp\u003eThe images were reviewed randomly by 2 experienced radiologists, each with more than 10 years of experience. They were blinded to the clinical information and conducted their reviews independently. Image analyses of MRBTI and CTV were conducted independently with a time interval of 2 weeks for the absence or presence of DVT (yes/no) in the vessel segments of both sides.\u003c/p\u003e \u003cp\u003eA total of 10 groups of venous segments were included in the image analysis: for the above/around-knee deep vein network segments: popliteal vein, superficial femoral vein, deep femoral vein, common femoral vein, and external iliac vein; for the below-knee deep vein network segments: gastrocnemius vein, soleus vein, anterior tibial vein, posterior tibial vein, and fibular vein. Based on consensus, proximal DVT was defined as involvement of above/around-knee with or without below-knee veins, and distal DVT was defined as involvement of below-knee veins without above/around-knee veins.\u003c/p\u003e \u003cp\u003eTwo independent readers scored the aforementioned 10 named venous segments for quality using a 4-point scale defined as follows: grade 4\u0026thinsp;=\u0026thinsp;excellent visibility, no relevant artifacts; grade 3\u0026thinsp;=\u0026thinsp;good visibility, minimal inhomogeneity, only minor flow artifacts; grade 2\u0026thinsp;=\u0026thinsp;moderate visibility, delineated lumen, major flow artifacts; and grade 1\u0026thinsp;=\u0026thinsp;indicating poor visibility, insufficient for diagnosis. The diagnostic confidence was also evaluated on a 4-point scale: 4\u0026thinsp;=\u0026thinsp;excellent, exact diagnosis possible; 3\u0026thinsp;=\u0026thinsp;good, definite diagnosis possible; 2\u0026thinsp;=\u0026thinsp;fair, evaluation of major findings possible; and 1\u0026thinsp;=\u0026thinsp;poor, definite diagnosis impossible. The diagnostic confidence score was used to rate the confidence of a reader in diagnosing the thrombus, whether it was present or not.\u003c/p\u003e \u003cp\u003eThe 2 readers independently delineated a circular region of interest (ROI) in the midpiece of the thrombus to measure the mean signal intensity (SI\u003csub\u003ethrombus\u003c/sub\u003e), and the mean signal intensity of adjacent muscle (SI\u003csub\u003emuscle\u003c/sub\u003e) was delineated at the corresponding slice. The ROI size ranged from 20 to 35 mm\u0026sup2;. The signal intensity ratio (SIR) was calculated as SI\u003csub\u003emuscle\u003c/sub\u003e/SI\u003csub\u003ethrombus\u003c/sub\u003e. Simultaneously, the clot burden of each segment was scored by the radiologists independently: 0, patent vein segment; 1, nonocclusive thrombus; 2, subsegmental, occlusive thrombus; and 3, occlusive thrombus of the entire length of a segment.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using SPSS version 27 (IBM Corp., NY, USA). Normally distributed continuous variables were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, and asymmetrically distributed continuous variables were presented as median and interquartile range. The categorical variables were presented as counts (percentages). The Wilcoxon rank-sum test was used for continuous variables, and the chi-square test or Fisher\u0026rsquo;s exact test was used for categorical variables. The sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV, respectively), and accuracy were calculated. Interobserver agreement and agreement between standard US and MRBTI were tested using Cohen\u0026rsquo;s kappa test. The interobserver agreement for the image quality score was also determined using Cohen\u0026rsquo;s kappa test. The κ value was interpreted as follows: fair (κ\u0026thinsp;=\u0026thinsp;0.21\u0026ndash;0.40), moderate (κ\u0026thinsp;=\u0026thinsp;0.41\u0026ndash;0.60), substantial (κ\u0026thinsp;=\u0026thinsp;0.61\u0026ndash; 0.80), and excellent (κ\u0026thinsp;\u0026gt;\u0026thinsp;0.80) [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The interclass correlation coefficient (ICC) with a 95% confidence interval (CI) using the 2-way random effects model was performed to test the interobserver agreements for thrombus signal intensity. The ICC was interpreted as follows: \u0026lt;0.40 as poor, 0.40\u0026ndash;0.59 as fair, 0.60\u0026ndash;0.74 as good, and \u0026ge;\u0026thinsp;0.75 as excellent [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. A 2-tailed \u003cem\u003ep\u003c/em\u003e value of \u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eBaseline characteristics\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eof the patient\u003c/strong\u003e\u003cstrong\u003es\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe baseline characteristics of patients are summarized in Table 1. In this study, 76 patients with DVT [51 (67%) in the proximal DVT group and 25 (33%) in the distal DVT group] were finally enrolled. Hypertension was the most common comorbidity in the 2 groups (43.14%, 36%), and immobility was the leading risk factor for all patients (46.05%). Of the 76 patients included, 13.16% had a history of venous thromboembolism (VTE). The mean symptom duration of patients with proximal DVT was 5.88 \u0026plusmn; 2.86 days and that of distal DVT was 6.84 \u0026plusmn; 3.29 days (\u003cem\u003ep\u003c/em\u003e =0.192).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImage quality and diagnostic confidence of MRBTI\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe image quality of MRBTI is summarized in Table 2. In total, 1520 segments, 152 limbs, and 76 patients were evaluated. The average image quality score for 1520 venous segments for readers 1 and 2 were 3.78 \u0026plusmn; 0.48 and 3.77 \u0026plusmn; 0.49, respectively. The interobserver agreement was excellent for readers 1 and 2 in grading the image quality (\u0026kappa; = 0.821, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAmong the above/around-knee veins, venous visualization of 79.8% (reader 1, 607/760) and 80.4% (reader 2, 611/760) segments were rated as excellent. Among the below-knee veins, venous visualization of 80% (reader 1, 608/760) and 78.7% (reader 2, 598/760) segments were rated as excellent. The average image quality score for above/around-knee segments for readers 1 and 2 was 3.78 \u0026plusmn; 0.45 and 3.79 \u0026plusmn; 0.45, and that of below-knee segments was 3.77 \u0026plusmn; 0.51 and 3.76 \u0026plusmn; 0.52, respectively. Venous visualization of 12 of 1520 segments was determined to be poor (grade = 1). The reasons were motion artifacts (\u003cem\u003en\u003c/em\u003e = 6), artifacts related to B1 inhomogeneity (\u003cem\u003en\u003c/em\u003e = 5), and susceptibility artifacts from metallic intrauterine ring (\u003cem\u003en\u003c/em\u003e = 1). The average diagnostic confidence for all segments for readers 1 and 2 was 3.94 \u0026plusmn; 0.25 and 3.93 \u0026plusmn; 0.28, respectively, and the interobserver agreement was excellent for overall diagnostic confidence (\u0026kappa; = 0.872, \u003cem\u003ep\u003c/em\u003e \u0026lt;0.001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiagnostic performance of MRBTI and CTV compared with US\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 3 shows the number of thrombus segments diagnosed using MRBTI, CTV, and US. Of 1508 assessable venous segments after ruling out 12 segments with poor visualization (grade = 1), DVT was identified in 346 segments using US (Table 3). Reader 1 identified DVT in 329 vessel segments and reader 2 in 314 vessel segments using MRBTI images. According to the consensus reading of CTV, a thrombus was detected in 319 of 1508 vessel segments. Image examples are presented in Figures 1\u0026ndash;3.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 4 shows the SE and SP of MRBTI in detecting lower-extremity DVT, with US serving as the reference standard. Both readers identified 5 thrombi in the above/around-knee venous segments that were \u0026ldquo;false positives\u0026rdquo;: 2 in the external iliac veins, 1 in the common femoral vein, and 2 in the deep femoral veins. Both readers further missed 3 thrombi (\u0026ldquo;false negatives\u0026rdquo;), respectively in the common femoral, deep femoral, and popliteal veins. In addition, reader 1 evaluated 12 false-positive segments in below-knee venous segments and missed 31 segments that were classified as thrombosed in US, and reader 2 evaluated 17 false-positive segments in below-knee venous segments and missed 29 thrombosed segments.\u003c/p\u003e\n\u003cp\u003eFor reader 1, the comparison of the MRBTI with the standard US resulted in an SE of 90.08%, an SP of 98.54%, a PPV of 94.78%, an NPV of 97.12%, and an accuracy of 96.62% (Table 4). The corresponding values for reader 2 were an SE of 90.67%, an SP of 98.11%, a PPV of 93.39%, an NPV of 97.27%, and an accuracy ACC of 96.42%. The inter-reader reproducibility for the presence or absence of DVT for the MRBTI images was strong (\u0026kappa; = 0.948, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001). A detailed overview of the diagnostic performance of MRBTI compared with US is summarized in Table 4.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWhen CTV was compared with US, the readers correctly identified a thrombus in 249 of 346 vessel segments (71.96%): 141 proximal vessel segments (88.67%) and 108 distal vessel segments (57.75%). The comparison of the CTV with the US resulted in an SE of 94.04%, an SP of 71.97%, a PPV of 91.92%, an NPV of 78.06%, and an accuracy of 89.01%.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThrombus signal intensity and clot burden using MRBTI in lower-extremity DVT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor readers 1 and 2, the average thrombus signal intensity of all segments was 226.18 \u0026plusmn; 87.92 and 225.14 \u0026plusmn; 86.90, and the SIR was 1.69 \u0026plusmn; 0.54 and 1.70 \u0026plusmn; 0.54, respectively (Table 5). For reader 1, the SIR of above/around-knee veins were 1.52 \u0026plusmn; 0.51, and below-knee veins was 1.86 \u0026plusmn; 0.51; for reader 2, the SIR of above/around-knee veins were 1.54 \u0026plusmn; 0.50, and below-knee veins was 1.85 \u0026plusmn; 0.53. The interobserver agreement was excellent for overall SIRs (ICC: 0.974, 95% CI: 0.968-0.979, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001). The\u0026nbsp;venous clot burden score obtained using MRBTI ranged from 0 to 3, with an average of 0.49 \u0026plusmn; 0.99 for reader 1 and 0.50 \u0026plusmn; 0.99 for reader 2. The interobserver agreement for MRBTI in assessing clot burden was excellent (k = 0.866, \u003cem\u003ep\u003c/em\u003e \u0026lt;0.001).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study addressed the clinical value of noncontrast-enhanced MRBTI for detecting and evaluating lower-extremity DVT. Our analysis demonstrated that this technique rapidly provided excellent venous visualization of the entire lower-extremity venous networks, and high SE and SP for detecting DVT compared with CTV and US. It allowed direct visualization of the lower limb and pelvic veins, providing reliable semi-quantitative parameters of thrombus signal intensity and clot burden.\u003c/p\u003e \u003cp\u003eThe 3-station MRBTI scans provide fast data acquisition, high spatial resolution, and a large FOV in the craniocaudal direction of the entire lower limb, ensuring stable image quality [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Using SPACE sequence, MRBTI allows a 3-dimensional scan to be completed in a reasonable time (approximately 4 minutes) [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Additionally, black-blood preparation using DANTE was introduced to achieve effective flow signal suppression, capable of suppressing the signal of flow at a velocity as low as 1 mm/s [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In this study, 5 venous segments were identified with poor image quality due to the nonuniformity of the main magnetic field (B0) and the radiofrequency field (B1) of the MRI. This inhomogeneity was often observed at the edges of each station, resulting in fat suppression failure artifacts [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Although water excitation was employed for improved fat suppression, complete artifact elimination was hindered by the large FOV required for lower limb imaging. Further research is needed to develop more effective solutions to address these image inconsistencies.\u003c/p\u003e \u003cp\u003eThe current study demonstrated that MRBTI had the potential to be a noninvasive technique for diagnosing and mapping pelvic and lower-extremity DVT. In the present study, MRBTI indicated a high SP for the overall detection of DVT (98.54% for reader 1 and 98.11% for reader 2). Among the above/around-knee venous segments, both the readers identified 5 false-positive segments: 2 external iliac veins, 1 common femoral vein, and 2 deep femoral veins. Compared with CTV images, these 5 segments were also evaluated as false positives, indicating the presence of a thrombus. The false positives may have resulted from the thrombus missed during the US examination or formed between the US and MR scans [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. For the below-knee venous segments, the 2 readers detected 12 and 17 false-positive segments, reducing the SP to 97.87% and 96.95%, respectively. The slower blood flow in below-knee veins, which is impeded and aggravated by thrombosis, may contribute to insufficient suppression of blood flow signals, leading to these false positives [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCompared with DUS, the readers missed 3 false-negative segments in the above/around-knee vein segments using MRBTI, reducing the overall SE to 99.17%. Upon re-evaluation, iso-intense thrombi were observed in the common femoral and deep femoral veins, along with a small thrombus in the distal popliteal vein. For the below-knee vein segments, the SE of MRBTI for DVT detection was lower compared with that in the above/around-knee segments (83.15% and 84.23%, respectively), due to the thinner vein diameter and extensive branching [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. A previous study demonstrated that the SE of US for detecting DVT varied based on the location of the thrombus, and it ranged from 94.2% for proximal to 63.5% for distal veins [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. In contrast, MRBTI had a higher resolution and an improved definition of the vessel wall, improving the imaging of DVT.\u003c/p\u003e \u003cp\u003eThe signal intensity of the thrombus varies according to the onset time, and this heterogeneity could be visually observed using the MRBTI images. When coagulation and thrombus form, hemoglobin in the red blood cells undergoes a series of characteristic oxidative changes over time [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. In the early stage, the peptide chain structure surrounding deoxyhemoglobin remains intact, which cannot produce a paramagnetic effect that shortens the T1 relaxation time, resulting in an equal signal intensity of thrombus [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. During this period, a thrombus dominated by loosely structured deoxyhemoglobin is regarded as a newly formed \u0026ldquo;fresh\u0026rdquo; thrombus. Over time, iron within the thrombus is oxidized by inducible nitric oxide synthase, leading to the accumulation of paramagnetic Fe\u003csup\u003e3+\u003c/sup\u003e. The resulting methemoglobin-dominated thrombus exhibits high signal intensity, along with fibrin cross-linking and collagen deposition [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. In this study, MRBTI provided stable and reproducible thrombus signal intensity that can intuitively reflect the thrombus period. For both reviewers, the SIR of the below-knee venous segment was higher than that of the above/around-knee venous segments, which was consistent with the natural evolution of thrombosis. Several studies have reported that DVT typically starts in the calf veins and extends to the proximal veins [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Distinguishing between new and chronic thrombi based on thrombus signal intensity on MRBTI is a promising clinical application of this technology.\u003c/p\u003e \u003cp\u003eUnlike the CTV techniques, which indirectly identify thrombi through blood-filling defects, MRBTI allows the direct visualization of the thrombus and measurement of clot burden. The incidence of PTS is higher in patients with DVT with a considerable thrombus burden, and anticoagulation alone has limited effectiveness in such cases [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. For patients with a high thrombus burden in the acute stage, more aggressive thrombus removal measures should be considered to reduce clot load, protect venous valve function, and lower the incidence of PTS [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. In this study, MRBTI demonstrated excellent interobserver consistency in assessing clot burden, providing valuable quantitative information for DVT treatment decision-making.\u003c/p\u003e \u003cp\u003eThis study had certain limitations. First, the sample size was limited. However, 1520 venous segments were examined through MRBTI images and could be included in the thrombus detectability analysis. Second, this study used US as the reference standard rather than CTV. The SE of MRBTI may be erroneously reduced if US does not detect a clot really present. Contrast-enhanced magnetic resonance venography can be used as a reference standard, and MRBTI can be systematically evaluated in a further study. Third, a time interval exists between MRI and US examinations. The therapeutic doses of heparin were started immediately after the diagnosis of DVT. This biased the comparison of MRBTI and US in terms of thrombus detectability because a few thrombi may have been lysed.\u003c/p\u003e \u003cp\u003eIn conclusion, the MRBTI technology is highly accurate in detecting lower-extremity DVT with good to excellent SE and SP values. It provides a rapid, non-nephrotoxic method to evaluate the lower-extremity venous network and abdominopelvic veins in patients with DVT and can provide good image quality and reliable and stable thrombus signal values. Further prospective studies are needed to evaluate the diagnostic value of MRBTI in differentiating old from recurrent thrombi and its clinical benefit in providing a supplementary roadmap preoperatively.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eMRBTI, magnetic resonance black-blood thrombus imaging\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDVT, deep vein thrombosis\u003c/p\u003e\n\u003cp\u003eDANTE, delay alternating with nutation for tailored excitation\u003c/p\u003e\n\u003cp\u003eSPACE, sampling perfection with application-optimized contrasts using various flip angle evolutions\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePE, pulmonary embolism\u003c/p\u003e\n\u003cp\u003ePTS, post-thrombotic syndrome\u003c/p\u003e\n\u003cp\u003eSIR, signal intensity ratio\u003c/p\u003e\n\u003cp\u003eICC, interclass correlation coefficient\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWang and Sun were responsible for conceptualization; Wang, Sun, Tang, and Liu were responsible for data analysis; Zhang, Zhang, Stemmer, and Xie were responsible for supervision; Wang and Sun wrote the manuscript; Wang, Sun, Yang and Li were responsible for the experimental design; Stemmer, Yang, and Li reviewed and edited the manuscript; Yang contributed to project management and funding acquisition. All authors have read and agreed to publish the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by grants from the Beijing Hospitals Authority Clinical Medicine Development of Special Funding Support (ZLRK202306), the National Natural Science Foundation of China (92249301), the Beijing Hospitals Authority\u0026rsquo;s Ascent Plan (DFL20220303), and the Beijing Key Specialists in Major Epidemic Prevention and Control.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData sharing is not applicable to this article as no datasets were generated or analysed during the current study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the Declaration of Helsinki (as revised in 2013) and was approved by the Medical Ethics Committee of Beijing Chaoyang Hospital, Capital Medical University (ethical batch number:\u0026nbsp;2024 - KE - 25). All methods were carried out in accordance with relevant guidelines and regulations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors of this manuscript declare relationships with the following companies: A.S. and C.Z. are employees of Siemens Healthineers. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDi Nisio M, van Es N, B\u0026uuml;ller HR. Deep vein thrombosis and pulmonary embolism. Lancet. 2016;388(10063):3060\u0026ndash;73.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhan F, Tritschler T, Kahn SR, Rodger MA. Venous thromboembolism. 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Stroke. 2011;42(5):1237\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGersh KC, Nagaswami C, Weisel JW. Fibrin network structure and clot mechanical properties are altered by incorporation of erythrocytes. Thromb Haemost. 2009;102(6):1169\u0026ndash;75.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKearon C. Natural history of venous thromboembolism. Circulation. 2003;107:22\u0026ndash;30.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFedullo PF, Rubin LJ, Kerr KM, Auger WR, Channick RN. The natural history of acute and chronic thromboembolic disease: the search for the missing link. Eur Respir J. 2000;15(3):435\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrandoni P, Kahn SR. Post-thrombotic syndrome: prevalence, prognostication and need for progress. Br J Haematol. 2009;145(3):286\u0026ndash;95.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSartori M, Favaretto E, Cini M, Legnani C, Palareti G, Cosmi B. D-dimer, FVIII and thrombotic burden in the acute phase of deep vein thrombosis in relation to the risk of post-thrombotic syndrome. Thromb Res. 2014;134(2):320\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"595\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 331px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 1. Baseline characteristics of patients\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eProximal DVT \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; (\u003cem\u003en\u003c/em\u003e = 51)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDistal DVT \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(\u003cem\u003en\u003c/em\u003e = 25)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; (\u003cem\u003en\u003c/em\u003e = 76)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003evalue\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDemographics\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Age, year\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e61.37 \u0026plusmn; 14.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e60.56 \u0026plusmn; 14.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e61.11 \u0026plusmn; 14.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.817\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Male sex, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e28 (54.90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e12 (48.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e40 (52.63)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.748\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eComorbidities\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Smoking, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e12 (23.53)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;5 (20.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e17 (22.37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.957\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Drinking, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e11 (21.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;3 (12.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e14 (18.42)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.486\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Hypertension, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e22 (43.14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;9 (36.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e31 (40.79)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.729\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Diabetes, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;7 (13.73)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;2 (8.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e9 (11.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.728\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedical history\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Coronary artery disease, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;8 (15.69)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;3 (12.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e11 (14.47)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.935\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Cerebrovascular accident, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e11 (21.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;3 (12.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e14 (18.42)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.486\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Varicose veins, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;6 (11.76)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;4 (16.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e10 (13.16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.879\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Long bone fracture, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;4 (7.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;3 (12.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e7 (9.21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.868\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;History of malignancy, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;7 (13.73)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;2 (8.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e9 (11.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.728\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Major surgery, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e13 (25.49)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;4 (16.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e17 (22.37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.522\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Immobility, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e25 (49.02)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;7 (28.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e35 (46.05)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.135\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Previous VTE, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;7 (13.73)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;3 (12.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e10 (13.16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e＞.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean symptom duration (day)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003e5.88 \u0026plusmn; 2.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e6.84 \u0026plusmn; 3.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e6.2 \u0026plusmn; 2.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.192\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eContinuous data are presented as mean \u0026plusmn; standard deviation, and categorical data are presented as count (percentage). VTE = venous thromboembolism.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"1031\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"12\" style=\"width: 1031px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 2. Image quality of MRBTI as graded independently by 2 readers\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"5\" style=\"width: 426px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eImage quality of vessel according to reader 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"5\" style=\"width: 397px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eImage quality of vessel according to reader 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSegment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003eGrade 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eGrade 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eGrade 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eGrade 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eScore*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eGrade 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003eGrade 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003eGrade 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eGrade 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eScore*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbove/Around-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; External iliac vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.56 \u0026plusmn; 0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.53 \u0026plusmn; 0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Common femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.86 \u0026plusmn; 0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.87 \u0026plusmn; 0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Deep femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e141\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.93 \u0026plusmn; 0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e141\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.93 \u0026plusmn; 0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Superficial femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.72 \u0026plusmn; 0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.72 \u0026plusmn; 0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Popliteal vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e133\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.86 \u0026plusmn; 0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e139\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.89 \u0026plusmn; 0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e145\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e607\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.78 \u0026plusmn; 0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e141\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e611\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.79 \u0026plusmn; 0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBelow-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Fibular vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e134\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.88 \u0026plusmn; 0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e139\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.89 \u0026plusmn; 0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Anterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e128\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.82 \u0026plusmn; 0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.80 \u0026plusmn; 0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Posterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e126\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.79 \u0026plusmn; 0.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e117\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.74 \u0026plusmn; 0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Gastrocnemius vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e108\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.67 \u0026plusmn; 0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e106\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.64 \u0026plusmn; 0.61\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Soleal vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.70 \u0026plusmn; 0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e111\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.69 \u0026plusmn; 0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e608\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.77 \u0026plusmn; 0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e147\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e598\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.76 \u0026plusmn; 0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOver all\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e285\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e1215\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.78 \u0026plusmn; 0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e288\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1209\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e3.77 \u0026plusmn; 0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003csup\u003e*\u003c/sup\u003eValues are mean \u0026plusmn; standard deviation. Grade 1: poor visibility; grade 2: moderate visibility; grade 3: good visibility; and grade 4: excellent visibility.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMRBTI, Magnetic resonance black-blood thrombus imaging. \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"548\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" style=\"width: 548px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 3. Number of thrombus segments diagnosed using MRBTI, CTV, and US\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMRBTI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCTV\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSegment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003eReader 1/Reader 2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbove/Around-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; External iliac vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e30/30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e29\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Common femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e30/30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Deep femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e19/19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Superficial femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e38/39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Popliteal vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e43/43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e161/161\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e166\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e159\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBelow-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Fibular vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e38/36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Anterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e28/29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Posterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e31/37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Gastrocnemius vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e35/34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Soleal vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e35/38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp; Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e168/175\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e153\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e187\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 180px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOverall\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e329/314\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e319\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e346\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCTV, Computed tomography venography; MRBTI, magnetic resonance black-blood thrombus imaging; US, ultrasound.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"left\" width=\"990\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"17\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable 4. Sensitivity and specificity of MRBTI in detecting lower-extremity DVT, with US serving as the reference standard\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"9\"\u003e\n \u003cp\u003e\u003cstrong\u003eReader 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"10\"\u003e\n \u003cp\u003e\u003cstrong\u003eReader 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eSegment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eTP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eFP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eFN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eTN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eACC (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eSE (95%vCI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eSP (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ePPV (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eNPV (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eTP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eFP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eFN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eTN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eACC (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eSE (95%vCI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eSP (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ePPV (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eNPV (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eAbove/Around-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;External iliac vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.67 (95.27-99.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.36 (94.20-99.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (87.66-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (96.97-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e93.33 (77.93-99.18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.67 (95.27-99.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.36 (94.30-99.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (87.66-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (97.02-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e93.33 (77.93-99.18)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Common femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e121\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.68 (95.33-99.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.18 (95.52-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.67 (82.78-99.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.18 (95.52-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.67 (82.78-99.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e121\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.68 (95.33-99.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.18 (95.52-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.67 (82.78-99.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.18 (95.52-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.67 (82.78-99.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Deep femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.00 (94.34-99.59)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.51 (94.71-99.82)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.48 (93.81-99.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.25 (95.88-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.23 (95.86-99.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.00 (94.34-99.59)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.51 (94.71-99.82)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.48 (93.81-99.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.25 (95.88-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.23 (95.86-99.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Superficial femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (97.60-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (96.79-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (90.97-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (96.79-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (90.97-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (97.60-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (96.79-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (90.97-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (96.79-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (90.97-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Popliteal vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e107\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.34 (96.37-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (96.61-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.73 (87.98-99.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.07 (94.95-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (91.78-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e107\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.34 (96.37-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (96.61-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.73 (87.98-99.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.08 (94.99-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e100 (91.78-100.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e594\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.94 (97.94-99.54)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.17 (98.07-99.73)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.16 (95.49-99.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.50 (98.54-99.90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.49 (95.91-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e594\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.94 (97.94-99.54)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.17 (98.07-99.73)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.16 (95.49-99.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.50 (98.54-99.90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.49 (95.91-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eBelow-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Fibular vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e111\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.71 (92.49-98.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.23 (93.75-99.78)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.31 (79.13-98.38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.37 (92.50-99.45)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e94.74 (82.25-99.36)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e111\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.69 (92.44-98.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.11 (95.13-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e89.74 (75.78-97.13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.52 (91.33-99.04)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.22 (85.47-99.93)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Anterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e95.03 (90.68-98.12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e84.61 (65.27-95.49)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.39 (87.34-99.11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e88.00 (91.88-99.11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.55 (83.14-99.74)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e111\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e93.62 (88.99-96.54)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e84.00 (78.10-89.12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e95.68 (90.43-98.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e80.76 (66.72-91.23)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.52 (82.23-99.15)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Posterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e108\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.62 (87.17-96.26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e99.08 (94.99-99.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e75.00 (58.80-87.31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e91.53 (84.97-95.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.77 (83.30-99.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e105\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.00 (86.44-95.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.33 (90.87-98.99)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e80.49 (65.13-91.18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.92 (86.53-96.89)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e89.19 (74.58-96.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Gastrocnemius vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e105\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e91.95 (86.35-95.77)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.22 (92.10-99.42)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e78.05 (62.39-89.44)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.11 (85.54-96.33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e91.43 (76.94-98.20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e106\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.62 (87.17-96.26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.15 (93.47-99.77)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e78.05 (62.39-89.44)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.17 (85.66-96.36)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e94.12 (80.32-99.28)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Soleal vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e111\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e95.33 (90.62-98.10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.37 (92.50-99.45)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e88.89 (73.94-96.89)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.52 (91.33-99.04)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e91.43 (76.94-98.20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e109\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e94.67 (89.76-97.67)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e95.61 (90.06-98.56)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e91.67 (77.53-98.25)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.32 (92.37-99.44)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e86.84 (71.91-95.59)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e153\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e554\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e94.26 (92.45-95.78)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e83.15 (77.30-88.45)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.87 (87.79-99.62)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e92.72 (85.65-96.41)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e94.70 (82.13-99.25)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e542\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e93.81 (92.01-95.24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e84.23 (78.49-89.36)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.95 (83.14-99.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e90.12 (84.90-94.24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e94.92 (81.22-99.58)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eOverall\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e309\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1148\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.62 (95.61-97.47)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e90.08 (86.54-93.10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.54 (93.92-99.87)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e94.78 (82.53-99.37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.12 (87.22-99.34)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e311\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1143\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e96.42 (95.39-97.30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e90.67 (85.12-94.87)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e98.11 (97.18-98.82)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e93.39 (90.25-95.85)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e97.27 (96.21-98.14)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eACC, Accuracy; DVT, deep vein thrombosis; FN, true-negative; FP, false-positive; MRBTI, magnetic resonance black-blood thrombus imaging; SE, sensitivity; SP, specificity; NPV, negative predictive values; PPV, positive predictive values; TN, true-negative; TP, true-positive; US, ultrasound.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"9\" style=\"width: 832px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 5. Thrombus signal intensity and clot burden of MRBTI in lower-extremity DVT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 369px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eReader 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 413px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eReader 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSegment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003eThrombus signal intensity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003eMuscle signal intensity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003eSIR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003eClot burden\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003eThrombus signal intensity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003eMuscle signal intensity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eSIR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eClot burden\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbove/Around-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; External iliac vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e194.94 \u0026plusmn; 94.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e136.37 \u0026plusmn; 40.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.40 \u0026plusmn; 0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.48 \u0026plusmn; 1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e197.17 \u0026plusmn; 94.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e136.19 \u0026plusmn; 40.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.42 \u0026plusmn; 0.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.47 \u0026plusmn; 0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Common femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e186.52 \u0026plusmn; 70.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e135.29 \u0026plusmn; 33.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.38 \u0026plusmn; 0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.52 \u0026plusmn; 1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e186.75 \u0026plusmn; 68.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e133.48 \u0026plusmn; 33.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.40 \u0026plusmn; 0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.53 \u0026plusmn; 1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Deep femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e202.65 \u0026plusmn; 86.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e131.03 \u0026plusmn; 33.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.58 \u0026plusmn; 0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.29 \u0026plusmn; 0.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e201.88 \u0026plusmn; 85.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e128.24 \u0026plusmn; 33.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.59 \u0026plusmn; 0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.30 \u0026plusmn; 0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Superficial femoral vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e198.87 \u0026plusmn; 83.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e134.62 \u0026plusmn; 39.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.49 \u0026plusmn; 0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.73 \u0026plusmn; 1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e199.41 \u0026plusmn; 83.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e132.88 \u0026plusmn; 39.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.52 \u0026plusmn; 0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.73 \u0026plusmn; 1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Popliteal vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e221.83 \u0026plusmn; 84.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e128.12 \u0026plusmn; 31.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.72 \u0026plusmn; 0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.76 \u0026plusmn; 1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e219.44 \u0026plusmn; 82.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e127.66 \u0026plusmn; 30.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.70 \u0026plusmn; 0.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.74 \u0026plusmn; 1.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e202.42 \u0026plusmn; 83.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e132.92 \u0026plusmn; 35.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.52 \u0026plusmn; 0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.56 \u0026plusmn; 1.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e202.16 \u0026plusmn; 82.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e131.61 \u0026plusmn; 35.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.54 \u0026plusmn; 0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.55 \u0026plusmn; 1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBelow-knee\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Fibular vein\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e241.25 \u0026plusmn; 99.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e134.48 \u0026plusmn; 32.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.79 \u0026plusmn; 0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.52 \u0026plusmn; 0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e243.17 \u0026plusmn; 96.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e135.27 \u0026plusmn; 31.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.81 \u0026plusmn; 0.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.50 \u0026plusmn; 0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Anterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e243.17 \u0026plusmn; 81.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e139.75 \u0026plusmn; 33.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.76 \u0026plusmn; 0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.32 \u0026plusmn; 0.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e245.93 \u0026plusmn; 74.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e139.45 \u0026plusmn; 30.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.78 \u0026plusmn; 0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.34 \u0026plusmn; 0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Posterior tibial veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e241.12 \u0026plusmn; 75.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e130.77 \u0026plusmn; 34.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.88 \u0026plusmn; 0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.39 \u0026plusmn; 0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e227.20 \u0026plusmn; 83.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e129.05 \u0026plusmn; 38.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.79 \u0026plusmn; 0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.52 \u0026plusmn; 0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Gastrocnemius vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e258.23 \u0026plusmn; 95.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e139.56 \u0026plusmn; 31.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.84 \u0026plusmn; 0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.48 \u0026plusmn; 0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e262.96 \u0026plusmn; 90.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e140.26 \u0026plusmn; 30.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.87 \u0026plusmn; 0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.45 \u0026plusmn; 0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Soleal vein\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e258.65 \u0026plusmn; 74.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e130.58 \u0026plusmn; 32.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e2.01 \u0026plusmn; 0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.41 \u0026plusmn; 0.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e252.38 \u0026plusmn; 77.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e129.00 \u0026plusmn; 34.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e2.00 \u0026plusmn; 0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.45 \u0026plusmn; 0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u0026nbsp; Total\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e248.81 \u0026plusmn; 85.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e134.95 \u0026plusmn; 32.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.86 \u0026plusmn; 0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.42 \u0026plusmn; 0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e246.27 \u0026plusmn; 85.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e134.35 \u0026plusmn; 33.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.85 \u0026plusmn; 0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.45 \u0026plusmn; 0.87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOverall\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e226.18 \u0026plusmn; 87.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e133.96 \u0026plusmn; 34.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e1.69 \u0026plusmn; 0.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.49 \u0026plusmn; 0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e225.14 \u0026plusmn; 86.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e133.04 \u0026plusmn; 34.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1.70 \u0026plusmn; 0.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.50 \u0026plusmn; 0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eDVT, Deep vein thrombosis; MRBTI, magnetic resonance black-blood thrombus imaging; SIR, signal intensity ratio.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"magnetic resonance black-blood thrombus imaging, computed tomography, deep vein thrombosis, magnetic resonance imaging, ultrasound","lastPublishedDoi":"10.21203/rs.3.rs-6287435/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6287435/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjectives: \u003c/strong\u003eThis study aimed to evaluate the diagnostic performance of non-contrast magnetic resonance black-blood thrombus imaging (MRBTI) in detecting lower-extremity deep vein thrombosis (DVT) in comparison with computed tomography venography (CTV) and ultrasound (US).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eA total of 76 patients with consecutive lower-extremity DVT from March 2023 to February 2024 were included in this prospective study. All patients underwent MRBTI, CTV, and US. The image quality score and diagnostic confidence for MRBTI were determined by 2 readers independently using a 4-point scale. The sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive values (PPV and NPV, respectively) of MRBTI and CTV were calculated, using the values for US as the standard of reference. The thrombus signal intensity, signal intensity ratio (SIR), and clot burden were obtained in each thrombus segment, and interobserver agreement was calculated using the interclass correlation coefficient (ICC) and Cohen kappa coefficients (κ).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e The interobserver agreement was excellent for readers 1 and 2 in grading the quality score and diagnostic confidence level of the images (3.78 ± 0.48 vs 3.77 ± 0.49, κ = 0.821,\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; 3.94 ± 0.25 vs 3.93 ± 0.28, κ = 0.872,\u003cem\u003e p\u003c/em\u003e \u0026lt; 0.001, respectively).\u003cstrong\u003e \u003c/strong\u003eUsing the values for US as the standard, the SE, SP, PPV, NPV, and ACC of MRBTI were 90.08%, 98.54%, 94.78%, 97.12%, and 96.62% for reader 1 and 90.67%, 98.11%, 93.39%, 97.27%, and 96.42% for reader 2. Both readers strongly agreed on SIR measurements（ICC: 0.974, 95% CI: 0.968-0.979, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001）and had good agreement on clot burden （k = 0.866, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001）.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eNoncontrast-enhanced\u003cstrong\u003e \u003c/strong\u003eMRBTI accurately detected lower-extremity DVT and robustly quantified the entire lower-extremity thrombus signal, enabling pretreatment evaluation of deep veins in patients with DVT.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRegistry: \u003c/strong\u003eChinese Clinical Trial Registry\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration number: \u003c/strong\u003eChiCTR2500099260 (retrospectively registered)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRegistration Date: \u003c/strong\u003e2025-03-20 (retrospectively registered)\u003c/p\u003e","manuscriptTitle":"Evaluating Lower-Extremity Deep Vein Thrombosis using 3-Dimensional MR Black-Blood Thrombus Imaging: A Comparative Pilot Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-07 06:09:33","doi":"10.21203/rs.3.rs-6287435/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9897ae30-9030-4ea0-96db-8ba01700abc7","owner":[],"postedDate":"May 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-08-20T12:38:15+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-07 06:09:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6287435","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6287435","identity":"rs-6287435","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}