A Comparative Study of Pulmonary Artery Bifurcation Angle in Healthy Individuals and Patients with Acute and Chronic Pulmonary Embolism

A Comparative Study of Pulmonary Artery Bifurcation Angle in Healthy Individuals and Patients with Acute and Chronic Pulmonary Embolism | 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 A Comparative Study of Pulmonary Artery Bifurcation Angle in Healthy Individuals and Patients with Acute and Chronic Pulmonary Embolism Moslem Ahmadi, Nazanin Farshchian, Mohammad Gharib Salehi, Farhad Naleini This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6600462/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 Background : Recently, more studies have addressed the pulmonary artery bifurcation angle in CT angiography of lungs as a parameter in diagnosing pulmonary embolism. Objectives :The present study aimed to compare the pulmonary artery bifurcation angle in healthy individuals with patients with pulmonary embolism. Materials and Methods : This research was retrospective and case-control in type. The research population was patients visiting Imam Reza Hospital in Kermanshah (west of Iran) for CT angiography of lungs in the health records of 100 patients suspected of pulmonary embolism. After re-examination, the patients were divided into two groups: case (n=50) and control (n=50). Finally, the bifurcation angle of pulmonary artery in healthy individuals was compared and analyzed in SPSS 25. Results : As the results of independent-samples T -test showed, the minimum and maximum pulmonary artery bifurcation angle was 40 to 136 degrees (89.76 ± 25.869) in the control group and 41 to 144 degrees (91.66 ± 22.175) in the case group (P=0.694). As the main findings showed, the mean pulmonary artery bifurcation angle in the case group was slightly larger than the control group; however, this difference was not statistically significant (P<0.05). Conclusion : Although the mean pulmonary artery bifurcation angle in the case group was slightly larger than the control group, this difference was not statistically significant. Considering the contradictory finding with the only relevant study and the lack of further research to compare the results with and the importance of the topic, it is recommended that similar studies be conducted by specialists in other medical centers to obtain more definitive results. Pulmonary embolism CT angiography Pulmonary artery bifurcation angle Figures Figure 1 Figure 2 1. Introduction Pulmonary thromboembolism or pulmonary embolism (PE) is a clinical and pathophysiological syndrome caused by the obstruction of pulmonary artery or its branches by an embolus in the venous system or the right side of heart. In most cases, it resolves with no complications. In a number of patients, the thromboemboli do not resolve completely and may organize within the vessels, ultimately leading to the endothelialized fibrotic occlusion of vascular bed and pulmonary hypertension. In this condition, known as chronic thromboembolic pulmonary hypertension (CTEPH), the blood flow is diverted to other healthy parts of the pulmonary vasculature, leading to the remodeling of previously healthy vascular structures and impaired pulmonary circulation and respiratory function ( 1 – 3 ). However, PE is a threatening condition ( 2 ), leading to a significant impairment of cardiac function ( 4 ) and mortality in 13% of cases within 30 days ( 5 ). Therefore, a prompt diagnosis of PE and a favorable prognosis are crucial. It is integral to perform appropriate screening tests to select patients with the highest probability of diagnosis with PE ( 6 ). Pulmonary embolism is the third most common cause of mortality from cardiovascular diseases in Europe ( 7 ). The incidence of PE is lower in Asia ( 8 , 9 ). PE is reported in the emergency department with an estimated annual incidence of 39 to 115 per 100,000 people ( 10 ). The mortality rate of PE was previously reported to be 18 to 30% ( 11 ). More recent studies have reported the associated mortality to range between 1 and 3% ( 12 , 13 ). Following the increased introduction of computed tomography angiography of lungs, the incidence of PE has been associated with lower mortality rates and increased anticoagulant complications ( 14 , 15 ). The main problem in diagnosing PE is that certain symptoms (e.g., shortness of breath, chest pain, cough, or fever) are not specific to PE and may mask the disease because these symptoms are common to other diseases ( 2 , 16 , 17 , 18 ). Therefore, the use of more specific methods such as testing for markers such as D-dimer or lung imaging is essential for diagnosis. Computed tomography pulmonary angiography is the imaging method of choice to diagnose PE in high-risk patients or those suspected of PE and those with elevated D-dimer (22 − 19). Because this method is highly sensitive and specific, the diagnosis of the presence or absence of PE varies. Computed tomography pulmonary angiography has been reported to be false-positive for PE in up to 25% of cases, especially at the subsegmental and segmental levels (22 − 19). Any change in the main pulmonary artery and its branches directly affect the physiology and anatomy of these vessels ( 23 ). Studies have shown changes in the size of pulmonary artery in pulmonary blood pressure ( 24 ). Recently, a study pinpointed the geometry of pulmonary artery branch and changes in the bifurcation angle of pulmonary artery in the follow-up CT angiography of patients initially diagnosed with acute PE in diagnosing CTEPH ( 25 ). The results of this study suggested that a decrease in the bifurcation angle of pulmonary artery in the follow-up imaging of patients with acute PE can be considered a warning sign of progression to CTEPH. Since this disease can be life-threatening for patients, a lack of timely diagnosis or incorrect diagnosis can have consequences for patients. Therefore, it is essential to determine the associated diagnostic factors. The present study aimed to compare the bifurcation angle of pulmonary artery in CT angiography of healthy individuals with those with pulmonary embolism in visitors to Imam Reza Hospital in Kermanshah (western Iran). 2. Methodology The present retrospective case-control study was conducted in 2023-24 for seven months. This study was initiated after approval from the Vice Chancellor for Research and Ethics Committee of Kermanshah University of Medical Sciences (IR.KUMS.MED.REC.1402.094) at Imam Reza (AS) Educational, Medical and Research Center of Kermanshah. The research population included hospital records of patients with nonspecific respiratory symptoms within the past three years, from three weeks to three years after an initial acute PE event. The inclusion criteria were patients over 18 years of age who had undergone pulmonary CTAs for clinical suspicion of CTEPH. The exclusion criteria were patients with paracardiac tumoral lesions, mediastinal infiltration, severe umbilical lymphadenopathy (decided by the radiologist), severe motion artifacts, diffuse lung parenchymal disease, and severe scoliosis (determined subjectively by the radiologist) in the health record, or those in whom it was impossible to properly measure the pulmonary artery bifurcation angle. Using the patient's admission code, the researchers extracted the CT scans of lungs of the suspected patients from the PACS system and reviewed them via a design operator. Based on the presence or absence of vascular findings (intravascular filling defects, intravascular bands or webbing, arterial narrowing, arterial wall thickening, presence of collateral vessels, contrast reflux into the hepatic veins, flattening of the interventricular septum, and arterial wall calcification) and lung parenchyma (lung mosaic attenuation, signs of previous lung infarction, and pleural thickening) ( 26 ), the patients were divided into the case and control groups. In both groups, CT scans were extracted and the data were reconstructed in multiplanes so that the axial image angle was completely perpendicular to the trachea. The bifurcation angle was measured at a plane that allowed the visualization of the largest possible diameter of the right and left lungs. To measure the PA trunk, an image was used in which the ascending aorta and PA trunk were magnified to occupy at least 50% of the image. On the axial image, at the pulmonary bifurcation level, the maximum diameter in the axis perpendicular to the long axis of the PA was recorded as the pulmonary artery diameter. The right and left PAs were measured in an axis perpendicular to the long axis and at a distance of 1 cm from the bifurcation. The sampling method in this study was convenience and the sample size was estimated according to the study conducted by Abbasi et al. ( 25 ), in which the average pulmonary artery bifurcation angle in lung CT angiography was 68 degrees (60 to 92 degrees) in the group of patients, and 87 degrees (70 to 97 degrees) in the control group. In the follow-up, it was 71 degrees (41 to 94 degrees) in the group of patients and 91 degrees (83 to 101 degrees) in the control group. With a standard deviation of 7.75 and 13.25 in the case and control groups at a confidence interval of 95% and a test power of 90%, at least seven subjects in each group and 14 in total were estimated to enter the study. However, finally, 50 subjects were included in each group. Figures 1 and 2 are Pulmonary CT angiography and the bifurcation angle of pulmonary artery in a healthy individual and in a patient with pulmonary embolism in far and near views(Fig. 1 , 2 ) The data analysis was done in MS Excel and SPSS 25. The quantitative analysis of pulmonary artery bifurcation angle and age was presented in tables, graphs as data frequency, mean, median, variance, and standard deviation. Kolmogorov-Smirnov test was used to test the normality of interval variables. Chi-square test was used to measure variables across gender. Mann-Whitney U-test was used to examine age in the groups, and independent-samples T -test was used to compare the pulmonary artery bifurcation angle. A significance level of 0.05 was considered for all tests. 3. Findings The data from hospital records described 100 patients, 50 assigned to the case group and 50 to the control. There were 21 women and 29 men in the control group and 22 women and 28 men in the case group. In total, 43% of the sample were women and 57% were men. As the chi-square test results showed, the distribution of groups by gender did not differ significantly (P = 0.840). As the analysis showed, the mean age of all participants was 53.56 ± 16.041, which did not have a normal distribution (P = 0.033); however, the pulmonary artery bifurcation angle variable was 71.90 ± 23.990, which had a normal distribution (P = 0.200). Table 1 Minimum, maximum, median and mean of variables in research groups Variable Group Min Max x̄±SD Median Sig. Age control 28 95 89.15 ± 90.58 00.58 234.0 case 22 85 99.15 ± 16.54 00.55 total 22 95 04.16 ± 53.56 50.57 Pulmonary artery bifurcation control 40 136 86.25 ± 76.89 50.90 694.0 case 41 144 17.22 ± 66.91 00.89 total 40 144 99.23 ± 71.90 00.89 The age ranged from 28 to 95 years in the control group (58.90 ± 15.890) and 22 to 85 years in the case group (54.16 ± 15.998). There was no statistically significant difference between the two groups in age distribution. The bifurcation angle of pulmonary artery ranged between 40 and 136 degrees in the control group (89.76 ± 25.869) and 41 to 144 degrees in the case group. The most important finding was that the mean bifurcation angle of pulmonary artery was not significantly different between the case and control groups (Table 1 ). 4. Discussion and Conclusion The present study aimed to better diagnose patients with pulmonary embolism by comparing the bifurcation angle of pulmonary artery in healthy individuals with those with acute and chronic pulmonary embolism. Wittram et al (2004) reviewed the diagnosis of pulmonary embolism, and showed that in acute pulmonary embolism presented as complete arterial occlusion, the affected artery may be enlarged. Partial filling defects resulting from acute pulmonary embolism are often centrally located, but when located off-center, they form acute angles with the vessel wall. Chronic pulmonary embolism can appear as a complete obstructive disease in vessels smaller than adjacent vessels. Other findings on CT angiography of chronic pulmonary embolism include evidence for recanalization, filaments or flaps, and partial filling defects that form obtuse angles with the vessel wall. Factors that contribute to misdiagnosis of pulmonary embolism may be patient-related, technical, anatomical, or pathological. The radiologist must determine the quality of CT angiography study and whether a pulmonary embolism is present or not. If the quality of study is poor, the radiologist should determine which pulmonary arteries are obscured and whether additional imaging is required. In acute PE, circulatory failure and systemic hypotension are clinically important predictors of poor prognosis. However, hemodynamically unstable PE accounts for only a small proportion of PE presentations. Even if PA clot burden scores can be used to indicate the severity of the current episode of PE or the effectiveness of treatment, they may not be directly used as an indicator of RV failure or death in patients. Other clinical prognostic factors, such as the age above 70 years, congestive heart failure, or chronic obstructive pulmonary disease, are also considered poor prognostic factors. Large RV diameter with RV/LV ratio greater than 1.0 and/or obstructive thrombus and pulmonary infarction on initial CTPA, and high baseline pulmonary arterial pressure and RV dysfunction are independent predictors of CTEPH (27)., Doğan et al. (2015) reviewed the role of CT scanning in the diagnosis of acute and chronic pulmonary embolism, and showed that CT adds prognostic value by assessing right ventricular (RV) function. RV dysfunction assessed by CT and the location of the central embolus to a lesser extent predict PE-related mortality in normotensive and hypotensive patients whereas the PE embolic occlusion index has limited prognostic value. A simple RV/LV diameter ratio > 0.1 before risk predicts an adverse outcome. While ratios < 1.0 can safely exclude an adverse outcome (28), Hutchinson et al. (2015) in a retrospective review of the over diagnosis rate of pulmonary embolism with CT angiography (CTA) observed that in routine clinical practice, pulmonary emboli detected by pulmonary CTA are often over-diagnosed compared to the consensus of a group of thoracic radiologists. They recommended improving the quality of pulmonary CTA examinations and increasing awareness of potential diagnostic problems in pulmonary CTA to minimize misdiagnosis of pulmonary emboli (29). Albrecht et al. (2017) in Germany showed that pulmonary CTA is a rapid and reliable means of ruling out or diagnosing PE. Continuous improvements in CT system hardware and post-processing techniques have progressively reduced the need for radiation and contrast agents while improving image quality (30). Obmann et al. (2021) in the Netherlands showed that in predicting emboli with CTPA, a reduction in enhancement of more than 10 HU in the pulmonary vein relative to the atrium can provide additional and reassuring information in diagnosing PE (31) and et al. (2022) reviewed CT angiography in patients with embolism and contended that pulmonary vascular resistance or patient prognosis may not only be determined by mechanical occlusion of PA and their branches by intravascular clot chelates on CT angiography of the lung (CTPA), but also by vasoactive amines, reflex PA and systemic arterial vasoconstriction. Hypoxemia occurs during acute PE. Large RV diameter with RV/LV diameter ratio greater than one and/or presence of obstructive thrombus and pulmonary infarction on initial CTPA, and high baseline PA pressure and RV dysfunction are independent predictors of chronic thromboembolic pulmonary hypertension (CTE) (32). In a cross-sectional study in Iran, Abbasi et al. (2022) investigated changes in the bifurcation angle of pulmonary artery in the follow-up with computed tomography angiography (CTA) of patients with acute pulmonary embolism. Contrary to the present study, they observed a significant decrease in the bifurcation angle of pulmonary artery in patients with CTEPH. This parameter can be easily measured in lung CTA (25). In a cross-sectional study in Malaysia, Low et al. (2023) evaluated the performance of CTPA in diagnosing pulmonary embolism, and showed that factors such as gender, history of trauma, presence of COVID-19 infection and pneumonia were associated with positive CTPA. Male patients had higher chances of positive CTPA results. Patients with COVID-19 infection and pneumonia were more likely to have a negative CTPA result, highlighting the need for physicians to be more cautious in requesting CTPA in these patients (33). Khalifa et al (2023) in Egypt, studied the prognostic role of pulmonary CT angiography in patients with acute pulmonary embolism. They recommended the use of CTPA-derived indices of right ventricular dysfunction and pulmonary artery occlusion scores as predictors of prognosis in patients with acute PE (34). Youens et al. (2023) in Australi investigated the trends of using CTPA and its diagnostic yield in the treatment of pulmonary embolism. They observed that CTPA use increased from 2003 to 2015 while diagnostic yield decreased, potentially indicating over-testing. Despite the increased hospitalization, PE mortality remained stable, which could indicate over diagnosis (35). Yaghoubpour et al. (2024) conducted a systematic review and meta-analysis (Rio et al., 2014) to examine the prevalence of PE among trauma patients undergoing CTPA through a comprehensive search of PubMed, Scopus, Google Scholar, and Web of Science. They showed that the overall prevalence of PE among trauma patients undergoing CTPA was 18%. The most common clinical manifestations of PE among trauma patients included dyspnea, chest pain, and changes in vital signs. Radiological findings included various pulmonary abnormalities, such as opacities, ground-glass opacity, and pleural effusion. The mortality rate of PE among trauma patients ranged from 0% to 29.4% in the sample. As the present findings showed, a lower threshold for CTPA was recommended in patients with lower limb or spine fractures (36). The primary finding of the present study was that the mean pulmonary artery bifurcation angle in the case group was slightly larger than the control group; however, this difference was not statistically significant. The results of this study, unlike the study by Abbasi et al. (25), do not recommend the use of the pulmonary artery bifurcation angle as a measure of diagnosing pulmonary embolism. Considering the contradictory findings of the only study conducted on this topic and the lack of further studies to compare the results with and the importance of the matter, it is recommended that similar studies be conducted by specialists in other medical centers to obtain more definitive findings. Declarations Authors' Contribution : Study concept and design: M. A. and N. F.; Acquisition of data: M. A. Analysis and interpretation of data: M. G. and F. N. ; Drafting of the manuscript: N. F.; Critical revision of the manuscript for important intellectual content: M. G.; Statistical analysis: F. N. and N. F. Conflict of Interests Statement : The authors declare that they have no conflicts of interest. Data Availability : The dataset presented in the study is available on request from the corresponding author during submission or after publication. Ethical Approval : IR.KUMS.MED.REC.1402.094 Funding/Support : This research received no external funding; thanks to guidance and advice from "Clinical Research Development Unit of Emamreza Hospital". Informed Consent : All participants with potentially identifiable images or data provided written informed consent before inclusion in the study. References Kearon C. Diagnosis of pulmonary embolism. CMAJ. 2003; 168(2):183-194. Konstantinides SV, Torbicki A, Agnelli G, Danchin N,Fitzmaurice D, Galiè N, Gibbs JS, Huisman MV, Humbert M, Kucher N, et al. ESC guidelines on the diagnosis and management of acute pulmonary embolism. Eur Heart J. 2014; 35: 3033-3069. 3069a-3069k, 2014. Pengo V, Lensing AW, Prins MH, Marchiori A, Davidson BL, Tiozzo F, et al. Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism. N Engl J Med. 2004; 350:2257-64. doi: 10.1056/ NEJMoa032274. PubMed PMID: 15163775. Shopp JD, Stewart LK, Emmett TW and Kline JA. 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Doi:org/10.1007/s10140-024-02249-7 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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09:02:58","extension":"html","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":88116,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-6600462/v1/0fc1e3c832e1dcd327de8f52.html"},{"id":91829276,"identity":"03b26ad7-871a-4a2a-955f-18d1a8f600a4","added_by":"auto","created_at":"2025-09-22 08:54:58","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":438859,"visible":true,"origin":"","legend":"\u003cp\u003ePulmonary CT angiography and the bifurcation angle of pulmonary artery in a healthy individual in far and near views\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6600462/v1/7d37d00812fce7776decf8b7.png"},{"id":91829275,"identity":"d2f15435-5286-4676-ba00-df47737afdf5","added_by":"auto","created_at":"2025-09-22 08:54:58","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":537360,"visible":true,"origin":"","legend":"\u003cp\u003ePulmonary CT angiography and the bifurcation angle of pulmonary artery in a patient with pulmonary embolism in far and near views\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6600462/v1/b7acdc8f0130fd60979caf36.png"},{"id":93162962,"identity":"3443a0ff-de94-4b49-bbf0-a37aa3d7e522","added_by":"auto","created_at":"2025-10-09 17:16:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1678499,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6600462/v1/1e32ff99-751a-497c-bd19-a160e71293d9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A Comparative Study of Pulmonary Artery Bifurcation Angle in Healthy Individuals and Patients with Acute and Chronic Pulmonary Embolism","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003ePulmonary thromboembolism or pulmonary embolism (PE) is a clinical and pathophysiological syndrome caused by the obstruction of pulmonary artery or its branches by an embolus in the venous system or the right side of heart. In most cases, it resolves with no complications. In a number of patients, the thromboemboli do not resolve completely and may organize within the vessels, ultimately leading to the endothelialized fibrotic occlusion of vascular bed and pulmonary hypertension. In this condition, known as chronic thromboembolic pulmonary hypertension (CTEPH), the blood flow is diverted to other healthy parts of the pulmonary vasculature, leading to the remodeling of previously healthy vascular structures and impaired pulmonary circulation and respiratory function (\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). However, PE is a threatening condition (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), leading to a significant impairment of cardiac function (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) and mortality in 13% of cases within 30 days (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Therefore, a prompt diagnosis of PE and a favorable prognosis are crucial. It is integral to perform appropriate screening tests to select patients with the highest probability of diagnosis with PE (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003ePulmonary embolism is the third most common cause of mortality from cardiovascular diseases in Europe (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The incidence of PE is lower in Asia (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). PE is reported in the emergency department with an estimated annual incidence of 39 to 115 per 100,000 people (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). The mortality rate of PE was previously reported to be 18 to 30% (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). More recent studies have reported the associated mortality to range between 1 and 3% (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Following the increased introduction of computed tomography angiography of lungs, the incidence of PE has been associated with lower mortality rates and increased anticoagulant complications (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe main problem in diagnosing PE is that certain symptoms (e.g., shortness of breath, chest pain, cough, or fever) are not specific to PE and may mask the disease because these symptoms are common to other diseases (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Therefore, the use of more specific methods such as testing for markers such as D-dimer or lung imaging is essential for diagnosis. Computed tomography pulmonary angiography is the imaging method of choice to diagnose PE in high-risk patients or those suspected of PE and those with elevated D-dimer (22\u0026thinsp;\u0026minus;\u0026thinsp;19). Because this method is highly sensitive and specific, the diagnosis of the presence or absence of PE varies. Computed tomography pulmonary angiography has been reported to be false-positive for PE in up to 25% of cases, especially at the subsegmental and segmental levels (22\u0026thinsp;\u0026minus;\u0026thinsp;19).\u003c/p\u003e\u003cp\u003eAny change in the main pulmonary artery and its branches directly affect the physiology and anatomy of these vessels (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Studies have shown changes in the size of pulmonary artery in pulmonary blood pressure (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). Recently, a study pinpointed the geometry of pulmonary artery branch and changes in the bifurcation angle of pulmonary artery in the follow-up CT angiography of patients initially diagnosed with acute PE in diagnosing CTEPH (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). The results of this study suggested that a decrease in the bifurcation angle of pulmonary artery in the follow-up imaging of patients with acute PE can be considered a warning sign of progression to CTEPH. Since this disease can be life-threatening for patients, a lack of timely diagnosis or incorrect diagnosis can have consequences for patients. Therefore, it is essential to determine the associated diagnostic factors. The present study aimed to compare the bifurcation angle of pulmonary artery in CT angiography of healthy individuals with those with pulmonary embolism in visitors to Imam Reza Hospital in Kermanshah (western Iran).\u003c/p\u003e"},{"header":"2. Methodology","content":"\u003cp\u003eThe present retrospective case-control study was conducted in 2023-24 for seven months. This study was initiated after approval from the Vice Chancellor for Research and Ethics Committee of Kermanshah University of Medical Sciences (IR.KUMS.MED.REC.1402.094) at Imam Reza (AS) Educational, Medical and Research Center of Kermanshah. The research population included hospital records of patients with nonspecific respiratory symptoms within the past three years, from three weeks to three years after an initial acute PE event. The inclusion criteria were patients over 18 years of age who had undergone pulmonary CTAs for clinical suspicion of CTEPH. The exclusion criteria were patients with paracardiac tumoral lesions, mediastinal infiltration, severe umbilical lymphadenopathy (decided by the radiologist), severe motion artifacts, diffuse lung parenchymal disease, and severe scoliosis (determined subjectively by the radiologist) in the health record, or those in whom it was impossible to properly measure the pulmonary artery bifurcation angle.\u003c/p\u003e\u003cp\u003eUsing the patient's admission code, the researchers extracted the CT scans of lungs of the suspected patients from the PACS system and reviewed them via a design operator. Based on the presence or absence of vascular findings (intravascular filling defects, intravascular bands or webbing, arterial narrowing, arterial wall thickening, presence of collateral vessels, contrast reflux into the hepatic veins, flattening of the interventricular septum, and arterial wall calcification) and lung parenchyma (lung mosaic attenuation, signs of previous lung infarction, and pleural thickening) (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e), the patients were divided into the case and control groups. In both groups, CT scans were extracted and the data were reconstructed in multiplanes so that the axial image angle was completely perpendicular to the trachea. The bifurcation angle was measured at a plane that allowed the visualization of the largest possible diameter of the right and left lungs. To measure the PA trunk, an image was used in which the ascending aorta and PA trunk were magnified to occupy at least 50% of the image. On the axial image, at the pulmonary bifurcation level, the maximum diameter in the axis perpendicular to the long axis of the PA was recorded as the pulmonary artery diameter. The right and left PAs were measured in an axis perpendicular to the long axis and at a distance of 1 cm from the bifurcation.\u003c/p\u003e\u003cp\u003eThe sampling method in this study was convenience and the sample size was estimated according to the study conducted by Abbasi et al. (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), in which the average pulmonary artery bifurcation angle in lung CT angiography was 68 degrees (60 to 92 degrees) in the group of patients, and 87 degrees (70 to 97 degrees) in the control group. In the follow-up, it was 71 degrees (41 to 94 degrees) in the group of patients and 91 degrees (83 to 101 degrees) in the control group. With a standard deviation of 7.75 and 13.25 in the case and control groups at a confidence interval of 95% and a test power of 90%, at least seven subjects in each group and 14 in total were estimated to enter the study. However, finally, 50 subjects were included in each group. Figures\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e are Pulmonary CT angiography and the bifurcation angle of pulmonary artery in a healthy individual and in a patient with pulmonary embolism in far and near views(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eThe data analysis was done in MS Excel and SPSS 25. The quantitative analysis of pulmonary artery bifurcation angle and age was presented in tables, graphs as data frequency, mean, median, variance, and standard deviation. Kolmogorov-Smirnov test was used to test the normality of interval variables. Chi-square test was used to measure variables across gender. Mann-Whitney U-test was used to examine age in the groups, and independent-samples \u003cem\u003eT\u003c/em\u003e-test was used to compare the pulmonary artery bifurcation angle. A significance level of 0.05 was considered for all tests.\u003c/p\u003e"},{"header":"3. Findings","content":"\u003cp\u003eThe data from hospital records described 100 patients, 50 assigned to the case group and 50 to the control. There were 21 women and 29 men in the control group and 22 women and 28 men in the case group. In total, 43% of the sample were women and 57% were men. As the chi-square test results showed, the distribution of groups by gender did not differ significantly (P\u0026thinsp;=\u0026thinsp;0.840). As the analysis showed, the mean age of all participants was 53.56\u0026thinsp;\u0026plusmn;\u0026thinsp;16.041, which did not have a normal distribution (P\u0026thinsp;=\u0026thinsp;0.033); however, the pulmonary artery bifurcation angle variable was 71.90\u0026thinsp;\u0026plusmn;\u0026thinsp;23.990, which had a normal distribution (P\u0026thinsp;=\u0026thinsp;0.200).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMinimum, maximum, median and mean of variables in research groups\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" 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colname=\"c5\"\u003e\u003cp\u003ex̄\u0026plusmn;SD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMedian\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSig.\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003econtrol\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e89.15\u0026thinsp;\u0026plusmn;\u0026thinsp;90.58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" 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colname=\"c3\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e04.16\u0026thinsp;\u0026plusmn;\u0026thinsp;53.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e50.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003ePulmonary artery bifurcation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003econtrol\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e136\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e86.25\u0026thinsp;\u0026plusmn;\u0026thinsp;76.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e50.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e694.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ecase\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e144\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e17.22\u0026thinsp;\u0026plusmn;\u0026thinsp;66.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e00.89\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003etotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e144\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e99.23\u0026thinsp;\u0026plusmn;\u0026thinsp;71.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e00.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe age ranged from 28 to 95 years in the control group (58.90\u0026thinsp;\u0026plusmn;\u0026thinsp;15.890) and 22 to 85 years in the case group (54.16\u0026thinsp;\u0026plusmn;\u0026thinsp;15.998). There was no statistically significant difference between the two groups in age distribution. The bifurcation angle of pulmonary artery ranged between 40 and 136 degrees in the control group (89.76\u0026thinsp;\u0026plusmn;\u0026thinsp;25.869) and 41 to 144 degrees in the case group. The most important finding was that the mean bifurcation angle of pulmonary artery was not significantly different between the case and control groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"4. Discussion and Conclusion","content":"\u003cp\u003eThe present study aimed to better diagnose patients with pulmonary embolism by comparing the bifurcation angle of pulmonary artery in healthy individuals with those with acute and chronic pulmonary embolism.\u003c/p\u003e\n\u003cp\u003eWittram et al (2004) reviewed the diagnosis of pulmonary embolism, and showed that in acute pulmonary embolism presented as complete arterial occlusion, the affected artery may be enlarged. Partial filling defects resulting from acute pulmonary embolism are often centrally located, but when located off-center, they form acute angles with the vessel wall. Chronic pulmonary embolism can appear as a complete obstructive disease in vessels smaller than adjacent vessels. Other findings on CT angiography of chronic pulmonary embolism include evidence for recanalization, filaments or flaps, and partial filling defects that form obtuse angles with the vessel wall. Factors that contribute to misdiagnosis of pulmonary embolism may be patient-related, technical, anatomical, or pathological. The radiologist must determine the quality of CT angiography study and whether a pulmonary embolism is present or not. If the quality of study is poor, the radiologist should determine which pulmonary arteries are obscured and whether additional imaging is required. In acute PE, circulatory failure and systemic hypotension are clinically important predictors of poor prognosis. However, hemodynamically unstable PE accounts for only a small proportion of PE presentations. Even if PA clot burden scores can be used to indicate the severity of the current episode of PE or the effectiveness of treatment, they may not be directly used as an indicator of RV failure or death in patients. Other clinical prognostic factors, such as the age above 70 years, congestive heart failure, or chronic obstructive pulmonary disease, are also considered poor prognostic factors. Large RV diameter with RV/LV ratio greater than 1.0 and/or obstructive thrombus and pulmonary infarction on initial CTPA, and high baseline pulmonary arterial pressure and RV dysfunction are independent predictors of CTEPH (27)., Doğan et al. (2015) reviewed the role of CT scanning in the diagnosis of acute and chronic pulmonary embolism, and showed that CT adds prognostic value by assessing right ventricular (RV) function. RV dysfunction assessed by CT and the location of the central embolus to a lesser extent predict PE-related mortality in normotensive and hypotensive patients whereas the PE embolic occlusion index has limited prognostic value. A simple RV/LV diameter ratio \u0026gt; 0.1 before risk predicts an adverse outcome. While ratios \u0026lt; 1.0 can safely exclude an adverse outcome (28), Hutchinson et al. (2015) in a retrospective review of the over diagnosis rate of pulmonary embolism with CT angiography (CTA) observed that in routine clinical practice, pulmonary emboli detected by pulmonary CTA are often over-diagnosed compared to the consensus of a group of thoracic radiologists. They recommended improving the quality of pulmonary CTA examinations and increasing awareness of potential diagnostic problems in pulmonary CTA to minimize misdiagnosis of pulmonary emboli (29). Albrecht et al. (2017) in Germany showed that pulmonary CTA is a rapid and reliable means of ruling out or diagnosing PE. Continuous improvements in CT system hardware and post-processing techniques have progressively reduced the need for radiation and contrast agents while improving image quality (30). Obmann et al. (2021) in the Netherlands showed that in predicting emboli with CTPA, a reduction in enhancement of more than 10 HU in the pulmonary vein relative to the atrium can provide additional and reassuring information in diagnosing PE (31) and\u0026nbsp;et al. (2022) reviewed CT angiography in patients with embolism and contended that pulmonary vascular resistance or patient prognosis may not only be determined by mechanical occlusion of PA and their branches by intravascular clot chelates on CT angiography of the lung (CTPA), but also by vasoactive amines, reflex PA and systemic arterial vasoconstriction. Hypoxemia occurs during acute PE. Large RV diameter with RV/LV diameter ratio greater than one and/or presence of obstructive thrombus and pulmonary infarction on initial CTPA, and high baseline PA pressure and RV dysfunction are independent predictors of chronic thromboembolic pulmonary hypertension (CTE) (32). In a cross-sectional study in Iran, Abbasi et al. (2022) investigated changes in the bifurcation angle of pulmonary artery in the follow-up with computed tomography angiography (CTA) of patients with acute pulmonary embolism. Contrary to the present study, they observed a significant decrease in the bifurcation angle of pulmonary artery in patients with CTEPH. This parameter can be easily measured in lung CTA (25). In a cross-sectional study in Malaysia, Low et al. (2023) evaluated the performance of CTPA in diagnosing pulmonary embolism, and showed that factors such as gender, history of trauma, presence of COVID-19 infection and pneumonia were associated with positive CTPA. Male patients had higher chances of positive CTPA results.\u003c/p\u003e\n\u003cp\u003ePatients with COVID-19 infection and pneumonia were more likely to have a negative CTPA result, highlighting the need for physicians to be more cautious in requesting CTPA in these patients (33). Khalifa et al (2023) in Egypt, studied the prognostic role of pulmonary CT angiography in patients with acute pulmonary embolism. \u0026nbsp;They recommended the use of CTPA-derived indices of right ventricular dysfunction and pulmonary artery occlusion scores as predictors of prognosis in patients with acute PE (34). Youens et al. (2023) in Australi investigated the trends of using CTPA and its diagnostic yield in the treatment of pulmonary embolism. They observed that CTPA use increased from 2003 to 2015 while diagnostic yield decreased, potentially indicating over-testing. Despite the increased hospitalization, PE mortality remained stable, which could indicate over diagnosis (35). Yaghoubpour et al. (2024) conducted a systematic review and meta-analysis (Rio et al., 2014) to examine the prevalence of PE among trauma patients undergoing CTPA through a comprehensive search of PubMed, Scopus, Google Scholar, and Web of Science. They showed that the overall prevalence of PE among trauma patients undergoing CTPA was 18%. The most common clinical manifestations of PE among trauma patients included dyspnea, chest pain, and changes in vital signs. Radiological findings included various pulmonary abnormalities, such as opacities, ground-glass opacity, and pleural effusion. The mortality rate of PE among trauma patients ranged from 0% to 29.4% in the sample. As the present findings showed, a lower threshold for CTPA was recommended in patients with lower limb or spine fractures (36).\u003c/p\u003e\n\u003cp\u003eThe primary finding of the present study was that the mean pulmonary artery bifurcation angle in the case group was slightly larger than the control group; however, this difference was not statistically significant. The results of this study, unlike the study by Abbasi et al. (25), do not recommend the use of the pulmonary artery bifurcation angle as a measure of diagnosing pulmonary embolism. Considering the contradictory findings of the only study conducted on this topic and the lack of further studies to compare the results with and the importance of the matter, it is recommended that similar studies be conducted by specialists in other medical centers to obtain more definitive findings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthors' Contribution\u003c/strong\u003e: Study concept and design: M. A. and N. F.; Acquisition of data: M. A. Analysis and interpretation of data: M. G. and F. N. \u0026nbsp;; Drafting of the manuscript: N. F.; Critical revision of the manuscript for important intellectual content: M. G.; Statistical analysis: F. N. and N. F.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eConflict of Interests Statement\u003c/strong\u003e: The authors declare that they have no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eData Availability\u003c/strong\u003e: The dataset presented in the study is available on request from the corresponding author during submission or after publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;Ethical Approval\u003c/strong\u003e: IR.KUMS.MED.REC.1402.094\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding/Support\u003c/strong\u003e: This research received no external funding; thanks to guidance and advice from \"Clinical Research Development Unit of Emamreza Hospital\".\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eInformed Consent\u003c/strong\u003e: All participants with potentially identifiable images or data provided written informed consent before inclusion in the study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eKearon C. Diagnosis of pulmonary embolism. CMAJ. 2003; 168(2):183-194.\u003c/li\u003e\n \u003cli\u003eKonstantinides SV, Torbicki A, Agnelli G, Danchin N,Fitzmaurice D, Gali\u0026egrave; N, Gibbs JS, Huisman MV, Humbert M, Kucher N, et al. ESC guidelines on the diagnosis and management of acute pulmonary embolism. Eur Heart J. 2014; 35: 3033-3069. 3069a-3069k, 2014.\u003c/li\u003e\n \u003cli\u003ePengo V, Lensing AW, Prins MH, Marchiori A, Davidson BL, Tiozzo F, et al. Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism. N Engl J Med. 2004; 350:2257-64. doi: 10.1056/ NEJMoa032274. PubMed PMID: 15163775.\u003c/li\u003e\n \u003cli\u003eShopp JD, Stewart LK, Emmett TW and Kline JA. Findings from12-lead electrocardiography that predict circulatory shock from pulmonary embolism: Systematic review and meta-analysis. Acad Emerg Med. 2015; 22: 1127-1137.\u003c/li\u003e\n \u003cli\u003eSpencer FA, Gore JM, Lessard D, Douketis JD, Emery C and Goldberg RJ. Patient outcomes after deep vein thrombosis and pulmonary embolism: The worcester venous thromboembolism study. Arch Intern Med. 2008; 168: 425-430.\u003c/li\u003e\n \u003cli\u003eSikora-Skrabaka M, Skrabaka D, Ruggeri P, Caramori G, Skoczyński S, Barczyk A. D_dimer value in the diagnosis of pulmonary embolism\u0026mdash;may it exclude only? J Thorac Dis. 2019; 11(3): 664-672\u003c/li\u003e\n \u003cli\u003e\u003cspan dir=\"RTL\"\u003e7. Stein PD, Beemath A and Olson RE. Trends in the incidence of\u003c/span\u003e pulmonary embolism and deep venous thrombosis in hospitalized patients. Am J Cardiol. 2005; 95: 1525-1526.\u003c/li\u003e\n \u003cli\u003eJang MJ, Bang SM and Oh D: Incidence of venous thromboembolism in Korea. From the health insurance review and assessment service database. J Thromb Haemost. 2011; 9: 85‑91.\u003c/li\u003e\n \u003cli\u003eMolina JA, Jiang ZG, Heng BH and Ong BK. Venous thromboembolism at the National Healthcare Group, Singapore. Ann Acad Med Singapore. 2009; 38: 470-478.\u003c/li\u003e\n \u003cli\u003eWendelboe AM, Raskob GE. Global burden of thrombosis: epidemiologic aspects. Circ Res. 2016; 118: 1340-1347.\u003c/li\u003e\n \u003cli\u003eS\u0026oslash;gaard KK, Schmidt M, Pedersen L, et al. 30-Year mortality after venous thromboembolism: a population-based cohort study. Circulation. 2014; 130: 829-836.\u003c/li\u003e\n \u003cli\u003ePollack CV, Schreiber D, Goldhaber SZ, et al. Clinical characteristics, management, and outcomes of patients diagnosed with acute pulmonary embolism in the emergency department: initial report of EMPEROR (Multicenter Emergency Medicine Pulmonary Embolism in the Real World Registry). J Am Coll Cardiol. 2011; 57: 700-706.\u003c/li\u003e\n \u003cli\u003eJim\u0026eacute;nez D, De Miguel-D\u0026iacute;ez J, Guijarro R, et al. Trends in the management and outcomes of acute pulmonary embolism: analysis from the RIETE registry. J Am Coll Cardiol. 2016;67:162-170.\u003c/li\u003e\n \u003cli\u003eWiener RS, Schwartz LM, Woloshin S. Time trends in pulmonary embolism in the United States: evidence of overdiagnosis. Arch Intern Med. 2011; 171:831-837.\u003c/li\u003e\n \u003cli\u003eKonstantinides SV, Barco S, Lankeit M, et al. Management of pulmonary embolism: an update. J Am Coll Cardiol. 2016;67: 976-990\u003c/li\u003e\n \u003cli\u003eGjonbrataj E, Kim JN, Gjonbrataj J, Jung HI, Kim HJ, Choi W. Risk factors associated with provoked pulmonary embolism. Korean J Intern Med.2017; 32: 95-101.\u003c/li\u003e\n \u003cli\u003eHeit JA, Melton LJ III, Lohse CM, Petterson TM, Silverstein MD, Mohr DN and O\u0026apos;Fallon WM. Incidence of venous thromboembolism in hospitalized patients vs. community residents. Mayo Clin Proc. 2001; 76: 1102-1110.\u003c/li\u003e\n \u003cli\u003eBusse LW and Vourlekis JS: Submassive pulmonary embolism. Crit Care Clin. 2014; 30: 447-473.\u003c/li\u003e\n \u003cli\u003eHutchinson BD, Navin P, Marom EM, et al. Overdiagnosis of pulmonary embolism by pulmonary CT angiography. AJR Am J Roentgenol. 2015;205: 271-277.\u003c/li\u003e\n \u003cli\u003eCourtney DM, Miller C, Smithline H, et al. Prospective multicenter assessment of interobserver agreement for radiologist interpretation of multidetector computerized tomographic angiography for pulmonary embolism. J Thromb Haemost. 2010;8: 533-539.\u003c/li\u003e\n \u003cli\u003eRuiz Y, Caballero P, Caniego JL, et al. Prospective comparison of helical CT with angiography in pulmonary embolism: global and selective vascular territory analysis. Interobserver agreement. Eur Radiol. 2003;13 :823-829.\u003c/li\u003e\n \u003cli\u003eGhanima W, Nielssen BE, Holmen LO, et al. Multidetector computed tomography (MDCT) in the diagnosis of pulmonary embolism:interobserver agreement among radiologists with varied levels of experience. Acta Radiol. 2007; 48: 165-170.\u003c/li\u003e\n \u003cli\u003eKnobel Z, Kellenberger CJ, Kaiser T, Albisetti M, Bergstrasser E, Buechel ER. Geometry and dimensions of the pulmonary artery bifurcation in children and adolescents: assessment in vivo by contrast-enhanced MR-angiography. Int J Cardiovasc Imaging. 2011; 27: 385-96. doi: 10.1007/s10554-0109672-6. PubMed PMID: 20652636.\u003c/li\u003e\n \u003cli\u003eChin M, Johns C, Currie BJ, Weatherley N, Hill C, Elliot C, et al. Pulmonary Artery Size in Interstitial Lung Disease and Pulmonary Hypertension: Association with Interstitial Lung Disease Severity and Diagnostic Utility. Front Cardiovasc Med. 2018; 5:53. doi: 10.3389/fcvm.2018.00053. PubMed PMID: 29938208; PubMed Central PMCID: PMCPMC6003274.\u003c/li\u003e\n \u003cli\u003eAbbasi B, Darvish A, Akhavan R, Pezeshki Rad M, Farrokh D, et al. Decreased Pulmonary Artery Bifurcation Angle: A Novel Imaging Criterion for the Diagnosis of Chronic Pulmonary Thromboembolism. Iran J Med Sci July 2022; 47 (4): 360-366.\u003c/li\u003e\n \u003cli\u003eCastaner E, Gallardo X, Ballesteros E, Andreu M, Pallardo Y, Mata JM, et al. CT diagnosis of chronic pulmonary thromboembolism. Radiographics. 2009;29: 31\u0026ndash;50. doi: 10.1148/rg.291085061.\u003c/li\u003e\n \u003cli\u003e27. Wittram C, Maher MM, Yoo AJ, Kalra MK, Shepard JAO, McLoud TC. CT Angiography of Pulmonary Embolism: Diagnostic Criteria and Causes of Misdiagnosis. Radiographics. 2004 Sep-Oct;24(5):1219-38. doi: 10.1148/rg.245045008.\u003c/li\u003e\n \u003cli\u003eDoğan H, de Roos A, Geleijins J, Huisman MV, Kroft LJM.The role of computed tomography in the diagnosis of acute and chronic pulmonary embolism. Diagn Interv Radiol. 2015 Jul-Aug; 21(4): 307\u0026ndash;316. doi: 10.5152/dir.2015.14403\u003c/li\u003e\n \u003cli\u003eHutchinson BD, Navin P, Marom EM, Truong MT, Bruzzi JF. Overdiagnosis of Pulmonary Embolism by Pulmonary CT Angiography. AJR. 2015; 205:271-277.\u003c/li\u003e\n \u003cli\u003eAlbrecht MH, Bickford MW, Zhang L, Cecco CND, Wichmann JL, et al. State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism. AJR 2017; 208:495\u0026ndash;504. DOI:10.2214/AJR.16.17202.\u003c/li\u003e\n \u003cli\u003eHausmann D, Maher A, Sieroń DA, Huber AT,Obmann VC, et al. Detection of pulmonary embolism on CT-angiography using contrast attenuation of pulmonary veins. Acta Angiol 2021; 27, 1: 1\u0026ndash;9\u003c/li\u003e\n \u003cli\u003eAn J, Nam Y, Cho H, Chang J, Lee KS, et al. Acute Pulmonary Embolism and Chronic Thromboembolic Pulmonary Hypertension: Clinical and Serial CT Pulmonary Angiographic Features. J Korean Med Sci. 2022 Mar 14; 37(10): e76. doi: 10.3346/jkms.2022.37.e76\u003c/li\u003e\n \u003cli\u003e33.Low CL, Kow RY, Aziz AA, Yusof MM, Lim BC, et al. Diagnostic Yield of CT Pulmonary Angiogram in the Diagnosis of Pulmonary Embolism and Its Predictive Factors. Cureus. 2023 Jun; 15(6): e40484. doi: 10.7759/cureus.40484.\u003c/li\u003e\n \u003cli\u003eKhalifa AMM, Kamel FMM, Hafez EMA, AmerA.Prognostic role of CT pulmonary angiography in acute pulmonary embolism. AIN SHAMS MEDICAL JOURNAL. 2023; 74(2):345-363.\u003c/li\u003e\n \u003cli\u003eYouens D , Doust J, Wright C, Moorin R, et al. Computed Tomography Angiography for Detection of Pulmonary Embolism in Western Australia Shows Increasing Use with Decreasing Diagnostic Yield. J Clin Med. 2023 Feb; 12(3): 980. doi: 10.3390/jcm12030980\u003c/li\u003e\n \u003cli\u003eYaghoobpoor S, Fathi M, Taher HJ, Farhood AJ, Bahrami A, et al. Computed tomography pulmonary angiography (CTPA) for the detection of pulmonary embolism (PE) among trauma patients: a systematic review and meta-analysis. Emergency Radiology. 2024; 31:567\u0026ndash;580. Doi:org/10.1007/s10140-024-02249-7\u003c/li\u003e\n\u003c/ol\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":"Pulmonary embolism, CT angiography, Pulmonary artery bifurcation angle","lastPublishedDoi":"10.21203/rs.3.rs-6600462/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6600462/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: Recently, more studies have addressed the pulmonary artery bifurcation angle in CT angiography of lungs as a parameter in diagnosing pulmonary embolism.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjectives\u003c/strong\u003e:The present study aimed to compare the pulmonary artery bifurcation angle in healthy individuals with patients with pulmonary embolism.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and Methods\u003c/strong\u003e: This research was retrospective and case-control in type. The research population was patients visiting Imam Reza Hospital in Kermanshah (west of Iran) for CT angiography of lungs in the health records of 100 patients suspected of pulmonary embolism. After re-examination, the patients were divided into two groups: case (n=50) and control (n=50). Finally, the bifurcation angle of pulmonary artery in healthy individuals was compared and analyzed in SPSS 25.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: As the results of independent-samples \u003cem\u003eT\u003c/em\u003e-test showed, the minimum and maximum pulmonary artery bifurcation angle was 40 \u0026nbsp;to 136 \u0026nbsp;degrees (89.76 ± 25.869) in the control group and 41 \u0026nbsp;to 144 degrees (91.66 ± 22.175) in the case group (P=0.694). As the main findings showed, the mean pulmonary artery bifurcation angle in the case group was slightly larger than the control group; however, this difference was not statistically significant (P\u0026lt;0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e: Although the mean pulmonary artery bifurcation angle in the case group was slightly larger than the control group, this difference was not statistically significant. Considering the contradictory finding with the only relevant study and the lack of further research to compare the results with and the importance of the topic, it is recommended that similar studies be conducted by specialists in other medical centers to obtain more definitive results.\u003c/p\u003e","manuscriptTitle":"A Comparative Study of Pulmonary Artery Bifurcation Angle in Healthy Individuals and Patients with Acute and Chronic Pulmonary Embolism","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-22 08:54:53","doi":"10.21203/rs.3.rs-6600462/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":"3a819285-520f-4fa0-a9fe-1e68a6ec3e0c","owner":[],"postedDate":"September 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-09T17:08:36+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-22 08:54:53","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6600462","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6600462","identity":"rs-6600462","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}