Is a rapid MRI abdomen protocol for appendicitis useful for evaluation of ovarian torsion? 

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Sharon Gould, Tejal Moody, Mary Gould, Heidi Kecskemethy, Simone Veale, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4998787/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 31 Jan, 2025 Read the published version in Pediatric Radiology → Version 1 posted 11 You are reading this latest preprint version Abstract Background Diagnosis of adnexal torsion is challenging as presentation and imaging findings are non-specific. Objective Evaluate an MRI appendicitis protocol for adnexal torsion identification and determine if torsion can be excluded by limited abdominopelvic MRI. Materials and methods This retrospective study of females ages 1–19 who had limited abdominal MRI exams between 2013 and 2019. Radiologists measured ovaries and calculated ovarian volume ratios, stromal T2 signal ratios, and stromal ADC ratios. Adnexal cysts’ size, location, and relationship to the ovary were noted. Results Of 699 cases, 650 were included. Eight cases had surgically proven torsion. Significantly higher volume ratios were found in torsed cases (p < 0.001). A volume ratio greater than or equal to 4:1 had 75% sensitivity, 92% specificity, and 11.5% positive predictive value. A volume ratio less than 4:1 had 99.7% negative predictive value. Ovarian volumes greater than or equal to 20 mL had 87.5% sensitivity, 89.5% specificity, and 9.5% positive predictive value. A volume less than 20 mL had 99.8% negative predictive value. Four torsion cases had cysts greater than or equal to 5cm, including 2 cases without elevated ovarian volume ratio. Four of 5 cases with cysts greater than 7cm were torsed. Stromal T2 signal ratios for torsed cases were higher than non-torsed cases (p = 0.01). Stromal ADC ratio differences did not reach statistical significance (p = 0.46). Conclusion There was a 1.3% prevalence of torsion. Two cases were not detected by ovarian size or volume ratio but had large paratubal cysts. No torsion cases had normal appearing adnexa. Ovary torsion pediatric MRI adnexa Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 INTRODUCTION In females between 1 and 20 years of age, roughly 5 in 100,000 are affected by adnexal torsion [ 1 ]. Ovarian or adnexal torsion is reportedly found in 2.7% of females who had surgery for an acute abdomen [ 2 ]. Diagnosis of torsion is challenging because the signs and symptoms including nausea, vomiting, and persistent or colicky low abdominal pain that is often progressive and tender to palpation [ 1 , 3 – 8 ] may be present in other conditions including acute appendicitis [ 4 , 9 , 10 ]. As a result, only 30% of patients who undergo laparoscopy for suspected torsion are reported to have it [ 1 – 4 , 11 – 14 ]. For the same reason, the diagnosis of torsion may be delayed, resulting in an ovarian salvage rate of 13.6–27% [ 14 – 16 ]. Diagnostic laparoscopy is the gold standard for diagnosing adnexal torsion but is invasive and risky. Ultrasound is the most widely used modality for assessment of lower abdominal/pelvic pain and potential ovarian torsion because it is readily available, does not require ionizing radiation, and costs less than other cross-sectional imaging modalities [ 3 , 14 , 17 ]. Adequate adnexal evaluation with transabdominal technique requires a full bladder which may delay imaging while the bladder fills or require bladder catheterization if imaging cannot wait [ 18 ]. Even with a full bladder, imaging may still be suboptimal in patients with obesity. Transvaginal scanning is limited in the pediatric population to older teens who may be sexually active, or girls who use tampons or may have undergone intrauterine device (IUD) insertion. In addition to potential difficulty in getting an adequate pelvic sonogram, ultrasound criteria for the diagnosis of torsion are challenging as there may be overlap between torsed and untorsed ovaries [ 5 , 9 , 11 , 12 , 16 , 19 – 21 ]. Doppler signal evaluation may be confusing as some flow may be preserved in torsed ovaries [ 3 , 4 , 10 , 11 , 13 , 20 – 23 ]. CT is infrequently used in this instance due to poor ovarian visibility and ionizing radiation. MRI also is infrequently utilized due to limited availability, cost, and exam duration. When girls present with lower abdominal and pelvic pain, often there are multiple potential etiologies for that pain, including appendicitis or ovarian torsion [ 24 , 25 ]. Ultrasound remains the primary imaging for suspected ovarian torsion, but many girls present with less-specific lower abdominal or right lower quadrant pain and the working differential diagnosis for these patients includes both adnexal torsion and appendicitis. We sought to determine if there is a role for the rapid MRI scans performed frequently at our institution for appendicitis assessment in the evaluation of adnexal torsion. The exam duration is approximately 20 minutes and requires no sedation or IV contrast. We hypothesized that because the ovaries are visible in these images, assessing characteristics such as size, T2 signal, and diffusion would help distinguish normal from torsed adnexae. MATERIALS AND METHODS Institutional Review Board approved this retrospective study of the records and imaging of girls aged 1–19 who underwent limited MRI for appendicitis between 2013 and 2019. All reviews and data evaluation complied with HIPPA regulations. Informed consent was waived. Cases with incomplete MRI studies or non-visualization of one ovary were excluded as well as one transgender patient due to unknown hormonal status. Cases with surgically proven ovarian, adnexal (ovarian and tubal) or isolated tubal torsion were considered positive for torsion. Cases were considered negative for torsion if no torsion was found at surgery or if the discharge summary or emergency department (ED) disposition lacked mention or a diagnosis of ovarian, adnexal, or tubal torsion. The charts of all discharged patients without surgery were reviewed for an ED return within 48 hours. No patients who were initially discharged had a diagnosis of torsion upon ED return within 48 hours. Imaging was performed according to the standard departmental rapid protocol for suspected appendicitis. Studies were performed on any available MRI scanner, including both 1.5T and 3T units. Regardless of field strength, the protocol included a 3-plane single shot fast spin echo (SSFSE) localizer, coronal and axial non-fat saturated and fat-saturated T2-weighted SSFSE series and axial-diffusion-weighted imaging. All studies were performed without intravenous contrast. Three experienced radiologists reviewed the MRIs and measured the ovarian diameters in all three planes (Fig. 1 a). The size and location of ovarian or paratubal cysts were noted. Paratubal cysts that were clearly separate from the ovary were not included in ovarian measurements (Fig. 1 b). Regions of interest were placed on T2-weighted SSFSE images in the brightest area of each ovary within stroma excluding follicles, cysts, or areas of hemorrhage similar to the method described by Kato et al. [ 26 ] (Fig. 1 c). Regions of interest also were placed in the darkest area of ovarian stroma excluding regions of hemorrhage on the apparent diffusion coefficient (ADC) maps (Fig. 1 d). Calculations made from these measurements included larger to smaller ovarian volume ratios, stromal T2 signal ratios, and stromal ADC ratios. Data Analysis Patient and clinical characteristics were summarized by the presence or absence of torsion. Continuous variables were summarized using mean (SD) or median (IQR) as appropriate, while categorical variables were summarized using frequencies and percentages. Continuous variables also were categorized at the median to describe the distribution of torsion above or below the median of study variables. This method ensures robustness to outliers. Two-sample t-tests or Mann-Whitney U tests were used to compare means or medians as appropriate. Univariable logistic regression was used to determine the association between torsion and study variables. A multivariable backward stepwise logistic regression was conducted to determine the variables substantially associated with torsion, with a cut-off point of p = 0.10 to retain a variable in the model. Logistic regression and discriminant analysis were used to predict torsion using study variables. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were used to assess the predictive accuracy of study variables for predicting torsion. Model/test assumptions were checked, and appropriate measures were taken as needed. All tests were two-tailed with a significance level of 0.05. Statistical software R, version 4.3.2, was used for data analysis. RESULTS We identified 699 MRI scans performed with the appendicitis protocol for 667 girls with acute lower abdominal pain during the study period. Twenty-nine girls had the exam more than once during different ED visits in the study period, and one patient had 3 MRI scans. There were 653 complete examinations with ovaries visible bilaterally. One transgender patient undergoing hormonal therapy was excluded for concern of unpredictable hormonal influence on the ovaries. Two additional patients were excluded because the examination was performed for reasons other than acute lower abdominal/pelvic pain. Of the 650 patients included in the study, the median age was 13.5 years (range: 1.3–19.6 years). Of the patients with proven torsion, the median age was 13.3 years (range: 6.4–18.6 years). Sixty percent (n = 390) of the patients were menarchal, 26% (n = 168) were premenarchal, and 14% (n = 90) had undocumented menstrual status. Indications for the MRIs included right lower quadrant pain, generalized or other abdominal pain, high clinical suspicion of appendicitis, and abnormal or nondiagnostic findings on prior ultrasound studies. One hundred twenty-one cases underwent a laparoscopic or open surgical procedure after MRI, with two additional patients having percutaneous drainage of abscesses due to perforated appendicitis. The prevalence of torsion, either adnexal or tubal in our overall population was 1.3% (n = 8), with torsion identified in 6.5% of patients who went to surgery for either suspected torsion or suspected appendicitis. Ovarian torsion with or without associated adnexal torsion was identified and reduced laparoscopically in five patients (Table 1 ). The original MRI reports either described torsion or could not exclude torsion in all five cases of ovarian/adnexal torsion. Isolated tubal torsion without ovarian involvement was surgically reduced in three patients, with an associated paratubal cyst in all three cases. In these three cases, the original imaging reports correctly described the adnexal/paratubal cysts in each case but did not identify the isolated tubal torsion. In six other cases, the original MRI report raised a concern for ovarian torsion; however, no torsion was found for the two cases that went to surgery, one of which had an ovarian teratoma on the involved side, the other a ruptured hemorrhagic ovarian cyst. In the other four cases, one patient’s pain resolved, one patient was transferred to a general adult hospital with a diagnosis of pelvic inflammatory disease, and in two cases, a follow-up ultrasound was performed showing no findings concerning for ovarian/adnexal torsion. Five hundred nineteen cases did not require admission and were discharged (Table 1 ). Of these, 25 patients returned to the ED within 72 hours. No returning patients were subsequently diagnosed with adnexal or tubal torsion. Table 1 Final diagnoses of cases in our cohort Diagnosis Number of patients (n = 650) Ovarian/adnexal torsion 5 Isolated tubal torsion 3 Appendicitis (acute or ruptured) 111 Ovarian finding (teratoma, hemorrhagic cyst, ruptured follicle, dominant follicle) 57 Other a 474 a Other includes nonspecific abdominal pain, constipation, inflammatory bowel disease, pelvic inflammatory disease, Mittelschmerz, gastroenteritis, and urinary tract infection. Bilateral ovaries were measured in all cases. The average volume of untorsed adnexae was 8.25 mL (+/- 16.57) with a median of 5.89 mL (range 0.12–510). The average volume of torsed adnexae was 188.16 mL (+/- 237 mL) with a median of 70.23 mL (range 12.13–652.7; Fig. 2 ). When evaluating the largest adnexal volume for each patient, there was a significant difference in the median largest volume for torsed adnexae (70.2 mL; Q1 = 27.8, Q4 = 268) and untorsed adnexae (7.91 mL; Q1 = 2.82, Q4 = 13.3; p = < 0.0001) with overlap observed between groups (Fig. 3 ). An adnexal volume greater than or equal to 20 mL had an 87.5% sensitivity for torsion, 89.5% specificity, 9.5% PPV and a 99.8% NPV. We also assessed the ratio of adnexal volumes between the right and left sides. The median volume ratio of torsion cases was 9.57 (Q1 [25th percentile] = 3.84, Q3 [75th percentile] = 27.7). The median volume ratio of cases without torsion was 1.50 (Q1 = 1.23, Q4 = 2.21). Volume ratios in the torsed group were significantly higher than in the normal group (p < 0.001), although there was overlap (Fig. 4 ). A volume ratio greater than or equal to 4.0 was 75% sensitive and 92% specific for torsion; however, this value had only an 11.5% PPV for ovarian/adnexal torsion. A volume ratio less than 4.0 had a 99.7% NPV. Six of 650 cases had an ovarian or paratubal cyst 7 cm or greater, of which 83% (n = 5) of the cases also had torsion. Six cases had cysts greater than or equal to 5 cm but less than 7 cm, only one of which also had torsion (17%). This case had a high adnexal volume ratio of 11.7. Two torsion cases had no cyst, but both had an ovarian volume ratio greater than 3. Both torsion cases that had an ovarian volume ratio less than 4 had an adnexal cyst greater than or equal to 7cm that was not included in the ovarian measurement (Fig. 5 ). No torsion cases had normal-appearing adnexa on the involved side on MRI. T2 signal values tended to differ more between torsed and untorsed ovaries in the same patient than bilateral untorsed ovaries. The median T2 signal ratio comparing one ovary to the other in patients with torsion was 1.70 (Q1 = 1.34, Q4 = 2.23), which was significantly higher than in patients without torsion (1.21; Q1 = 1.09, Q4 = 1.40; p = 0.01). This ratio included cases where the torsed ovary was either brighter or darker on T2-weighted images than the uninvolved ovary (Figs. 2 a and 6 ). Although the T2 signal ratio difference between torsed and untorsed cases reached statistical significance, there was considerable overlap between the two groups due to outliers in the untorsed group (Fig. 7 ). The ADC value ratios for the torsed group tended to be larger than in the untorsed group but did not reach statistical significance. There were too few cases of torsion to separate premenarchal patients from post-menarchal patients for analysis. Univariable odds ratio analysis indicated vomiting, a volume ratio greater than 4, an adnexal volume of 20 mL or greater, and a cyst volume of 5 or larger, were all associated with increased odds of torsion (Table 2 ). On multivariable logistic regression analysis only a large adnexal volume ratio contributed significantly to prediction of torsion with an odds ratio of 1.572, 95% confidence interval of 1.153–2.197, p = 0.006. Table 2 Univariable odds ratio for torsion Variables Odds Ratio 95% CI Lower Upper P value Vomiting 8.768 1.548 164.381 0.04 Volume ratio (mL) 1.27 1.157 1.466 < 0.001 T2 signal ratio 2.52 1.322 4.702 0.002 Diffusion ratio 2.121 0.576 4.744 0.09 Largest volume (mL) 1.014 1.008 1.025 0.0003 Largest cyst measurement (cm) 3.152 1.837 7.716 0.001 DISCUSSION Our evaluation of the limited abdominal pelvic MRI protocol used at our institution for assessment of suspected appendicitis found adnexal appearance does correlate with potential adnexal torsion. Normal adnexal size of less than 20 mL, symmetric adnexal volumes with a ratio less than 4, and the absence of a large adnexal cyst of 5 cm or more had a high NPV for torsion. Abnormal adnexal volume and volume ratio did not perform as well at predicting torsion. Most imaging findings associated with adnexal torsion are non-specific and overlap with physiologic changes and non-surgical entities including enlargement and abnormal echogenicity of the involved ovary, involved ovarian position closer to the midline, shift of the uterus toward the affected side, fallopian tube thickening, and reduced, absent or abnormally high resistance vascular waveforms in the involved ovary [ 5 , 9 – 11 , 13 , 18 , 21 , 26 , 28 – 31 ]. Peripheral arrangement of follicles with follicular fluid/fluid levels, a follicular ring sign on ultrasound or MRI, a “whirlpool sign” of twisted adnexal vessels and a beaked appearance of the adnexal margin are specific findings but are not always seen, making imaging-based diagnosis of ovarian torsion difficult [ 9 – 11 , 13 , 18 , 20 , 21 , 22 , 27 , 29 – 34 ]. Asymmetric enlargement of the torsed adnexa has been described as a common finding [ 35 ], but is not always present [ 3 , 6 – 8 , 10 – 14 , 18 , 20 – 23 , 27 , 32 , 36 ]. An adnexal volume less than 20mL had a 99.8% NPV for torsion in our cohort, similar to prior studies in menarchal girls [ 6 , 11 , 37 ]. An adnexal volume greater than or equal to 20 mL was 87.5% sensitive and 89.5% specific for torsion and was associated with increased odds of torsion. A volume ratio less than 4 had a very high NPV of 99.7% for torsion. The PPV of MRI for torsion based on volume ratio was poor at 11.5%; however, it had a moderate sensitivity and good specificity at 75% and 92%, respectively. There were 67 non-torsion cases with adnexal volumes over 20 mL and 46 cases with adnexal volume ratios greater than 4 that may have had physiologic ovarian enlargement due to recent follicular rupture, hemorrhagic cysts, pelvic inflammatory disease or a corpus luteum. As has been previously reported [ 9 , 11 , 19 , 22 , 27 ], we found that an asymmetrically enlarged ovary is concerning because of increased odds for torsion but has a low PPV for torsion when considered alone. The T2 signal of torsed ovaries tended to differ from normal ovaries. On T2-weighted images, torsed ovarian signal can be higher than the unaffected ovary due to stromal edema from venous congestion soon after torsion or darker than the normal ovary from infarct or hemorrhage after more prolonged torsion [ 26 , 28 , 31 , 33 , 34 , 38 – 44 ]. The ratio of signal intensities did reach statistical significance in our analysis; however, the values overlapped a great deal with normal patients – more so than the volume ratios. Variation in ovarian signal on a physiological basis or due to pathology other than torsion can appear similar to the signal differences associated with torsion [ 41 ]. T2 signal ratios in our study overlapped between groups with and without torsion. Due to the small number of torsion cases, we could not evaluate a combined predictive value of the volume and T2 signal ratios. The ADC ratio values had the greatest amount of overlap between groups and did not reach statistical significance. This is contradictory to previously reported differences in ADC values for torsed and non-torsed ovaries [ 36 , 45 ], possibly due to the lower resolution, rapid MRI protocol used in our study population with decreased spatial resolution. More study is needed in this area. In our population, we encountered adnexal torsion prevalence of 1.3%, with torsion present in 6.5% of patients who went for surgery, which was higher than the 2.7% reported by Hibbard [ 2 ]; although their population included patients of all ages. Our study was retrospective and patients with a high suspicion of adnexal torsion based on clinical or pelvic ultrasound findings would not have undergone the MRI for appendicitis imaging. For this reason, additional study is needed to assess the performance of MRI in patients with a higher pretest probability of torsion as well as in a cohort with a larger number of torsion cases to improve the statistical analysis. Additionally, our specificity for torsion prediction was significantly less than that reported in pregnant patients by Lee et al. [ 31 ]; however, this may be due to the lower resolution, rapid MRI technique evaluated in our study. Both false negative cases that had a volume ratio less than 4, and the false negative case with an ovarian volume less than 20 mL, involved isolated tubal torsion with large paratubal cysts and normal ovaries. The ovarian volume ratios and ovarian volume for these cases were low because the ovaries were not torsed and, therefore, were unenlarged and the paratubal cysts were not included in the adnexal volume measurements. A normal appearing ovary in the instance of isolated tubal torsion has been previously reported [ 30 , 46 – 49 ]. On ultrasound, adnexal structures may be difficult to differentiate and a paratubal cyst may appear to arise from the ovary, and would, therefore, be included in the adnexal measurement [ 11 , 50 ]. In some of our cases, the MRI appearance of the adnexa permitted distinction of the paratubal cysts from the ovaries due to improved definition of soft tissue structures. In comparison, the diameter of a normal fallopian tube should be less than or equal to 1 cm [ 50 ]. These cases emphasize the presence of large paratubal cysts or other lesions and should be considered as paratubal abnormalities and tubal dilatation have been described as being lead points for both adnexal and isolated tubal torsion [ 3 , 18 , 34 , 46 , 47 , 49 ]. As this study was retrospective in nature, ovarian sizes and volumes were not reported on the initial interpretations; adnexal cysts or lesions or abnormal adnexal appearance were reported. Imaging techniques varied slightly across cases due to differences in scanner platforms and field strengths. This variability may underscore the reliability of our findings across MRI protocols. We assumed patients did not have torsion if torsion was not diagnosed at the initial visit and the patient did not return within 72 hours. We may have missed patients who sought care at another institution after their initial discharge. No patients who returned were subsequently diagnosed with torsion. Lastly, we had a small number of torsion cases, which almost certainly affected the statistical analysis. Normal ovarian volumes in the presence of adnexal torsion have been reported, particularly in younger girls [7,16,20,]. No patients with torsion of the ovary or ovary and fallopian tube in our cohort had a normal or symmetric adnexal volume. Linam et al. reported differences in adnexal volumes for premenarchal versus post-menarchal patients with torsion [ 11 ]; however, our cohort included only two premenarchal patients with torsion, preventing separate analyses of the two developmental groups. Further study is required to prospectively assess the efficacy of MRI for exclusion of adnexal torsion, particularly in a population who may have a higher prevalence of torsion, a larger number of cases with torsion, and a larger representation of premenarchal versus menarchal girls. Further investigation of rapid protocol MRI as a primary imaging modality for differential diagnosis of appendicitis versus ovarian torsion in girls presenting to the ED is required. MRI as a primary modality may prove useful for contributing to a combined imaging and clinical scoring system for predicting ovarian torsion, which would improve diagnosis of the uncommon torsion patients without ovarian enlargement [ 12 , 37 ], but prospective study is needed. CONCLUSION A short, non-contrast MRI protocol used for evaluation of acute appendicitis is reliable for excluding adnexal torsion in patients who do not have high clinical or ultrasound suspicion for torsion and who have symmetric appearing adnexae with no large adnexal cysts measuring greater than 5 cm. More study is needed to confirm these findings in patients who may have a higher pretest probability of torsion. Ultrasound remains the primary tool for patients with a high suspicion of torsion due to its greater availability and lower cost. Declarations Author Contribution Conceptualization: Sharon Gould, Arvind Choudhary; Methodology: Sharon Gould, Arvind Choudhary, Heidi Kecskemethy; Formal analysis and investigation: Sharon Gould, Tejal Mody, Arvind Choudhary, Simone Veale, Mary Gould; Writing - original draft preparation: Sharon Gould; Writing - review and editing: Sharon Gould, Heidi Kecskemethy, Tejal Mody, Arvind Choudhary; Resources: Sharon Gould, Heidi Kecskemethy; Supervision: Sharon Gould, Heidi Kecskemethy. Acknowledgement Simone Veale and Mary Gould were supported by the Nemours Departments of Biomedical Research (through the Nemours Summer Undergraduate Research Program) and Medical Imaging. 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Emerg Radiol 21:179–187 Dahmoush H, Anupindi SA, Pawel BR, Chauvin NA (2017) Multimodality imaging findings of massive ovarian edema in children. Pediatr Radiol 47:576–583 Bader T, Ranner G, Haberlik A (1996) Torsion of a normal adnexa in a premenarcheal girl: MRI findings. Eur Radiol 6:704–706 Jain KA (1995) Magnetic resonance imaging findings in ovarian torsion. Magn Reson Imaging 13:111–113 Van Kerkhove F, Cannie M, Op de Beeck K et al (2007) Ovarian torsion in a premenarcheal girl: MRI findings. Abdom Imaging 32:424–427 Bekci T, Polat AV, Aslan K, Tomak L, Ceyhan Bilgici M, Danaci M (2016) Diagnostic performance of diffusion-weighted MRI in the diagnosis of ovarian torsion: comparison of torsed and nonaffected ovaries. Clin Imaging 40:1029–1033 Gross M, Blumstein SL, Chow LC (2005) Isolated fallopian tube torsion: a rare twist on a common theme. AJR Am J Roentgenol 185:1590–1592 Propeck PA, Scanlan KA (1998) Isolated fallopian tube torsion. AJR Am J Roentgenol 170:1112–1113 Orazi C, Inserra A, Lucchetti MC, Schingo PM (2006) Isolated tubal torsion: a rare cause of pelvic pain at menarche. Sonographic and MR findings. Pediatr Radiol 36:1316–1318 Casey RK, Damle LF, Gomez-Lobo V (2013) Isolated fallopian tube torsion in pediatric and adolescent females: a retrospective review of 15 cases at a single institution. J Pediatr Adolesc Gynecol 26:189–192 Back SJ, Merrow AC (2016) Case 4: an adolescent girl with left lower quadrant pain. Pediatr Radiol 46:1068–1074 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 31 Jan, 2025 Read the published version in Pediatric Radiology → Version 1 posted Editorial decision: Revision requested 24 Sep, 2024 Reviews received at journal 14 Sep, 2024 Reviews received at journal 10 Sep, 2024 Reviews received at journal 05 Sep, 2024 Reviewers agreed at journal 04 Sep, 2024 Reviewers agreed at journal 04 Sep, 2024 Reviewers agreed at journal 03 Sep, 2024 Reviewers invited by journal 01 Sep, 2024 Editor assigned by journal 29 Aug, 2024 Submission checks completed at journal 29 Aug, 2024 First submitted to journal 29 Aug, 2024 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. 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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-4998787","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":358520205,"identity":"db9a3b89-a8bb-4299-990c-f389f0171a5e","order_by":0,"name":"Sharon Gould","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABA0lEQVRIiWNgGAWjYBAC+RlQmoGBuUHiAzFaDG5AaMMGBsYGyRlEaZGA0AkMQC3SPERpkW5+9uHjDoYEfonExtu2O2yi+SVyH39gqLhn14BDi/ycY8YzZ55hSJCckdhsnXsmLXfmjHQzCYYzxcm4tDDcSDBm5m1jSN5wI7FNOrftcO6GG2lsDIxtCck4XXYj/TNISyJYi2Xbf5AW5g/4teQYI7Qwth0AaWGQAGqxw+n9GznFjDPbJAxn9jxstuxtS86d2fOMTSLhTEICLi3yM9I3M3xss5HnZ08+eONnm11uPzvQYR8qEuxxOgwCJND4QCsSGwjowQSEbBkFo2AUjIKRAwBj01jRKcjACQAAAABJRU5ErkJggg==","orcid":"","institution":"Nemours Children's Health","correspondingAuthor":true,"prefix":"","firstName":"Sharon","middleName":"","lastName":"Gould","suffix":""},{"id":358520206,"identity":"8dc01538-b923-45d6-aac4-edeb00d21ba3","order_by":1,"name":"Tejal Moody","email":"","orcid":"","institution":"Nemours Children's Health","correspondingAuthor":false,"prefix":"","firstName":"Tejal","middleName":"","lastName":"Moody","suffix":""},{"id":358520207,"identity":"4e68eba0-c9a9-4955-9658-0984544b7513","order_by":2,"name":"Mary Gould","email":"","orcid":"","institution":"Medical University of South Carolina","correspondingAuthor":false,"prefix":"","firstName":"Mary","middleName":"","lastName":"Gould","suffix":""},{"id":358520208,"identity":"f81749e5-3020-4900-8288-608050f965de","order_by":3,"name":"Heidi Kecskemethy","email":"","orcid":"","institution":"Nemours Children's Health","correspondingAuthor":false,"prefix":"","firstName":"Heidi","middleName":"","lastName":"Kecskemethy","suffix":""},{"id":358520209,"identity":"002c1a34-8f14-4070-a6c7-1834bc3767f6","order_by":4,"name":"Simone Veale","email":"","orcid":"","institution":"University of North Carolina at Chapel Hill","correspondingAuthor":false,"prefix":"","firstName":"Simone","middleName":"","lastName":"Veale","suffix":""},{"id":358520210,"identity":"e4c3bf30-ceab-41c7-a03e-62cfaae5f09f","order_by":5,"name":"Arabinda Choudhary","email":"","orcid":"","institution":"University of Arkansas Medical Center","correspondingAuthor":false,"prefix":"","firstName":"Arabinda","middleName":"","lastName":"Choudhary","suffix":""}],"badges":[],"createdAt":"2024-08-29 15:26:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4998787/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4998787/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00247-025-06170-0","type":"published","date":"2025-01-31T15:57:29+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":66941698,"identity":"d47d9290-0d35-4c77-97bd-0378d7c73c55","added_by":"auto","created_at":"2024-10-18 08:59:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1213184,"visible":true,"origin":"","legend":"\u003cp\u003ea) An axial fat-suppressed single shot fast spin echo (SSFSE) image though the pelvis of a 14-year-old girl with right lower quadrant pain shows an unremarkable left ovary with calipers in place for ovarian measurement. Measurement of the height of the ovary was obtained from coronal images. b) A 10-year-old-girl with abdominal pain concerning for appendicitis (a different patient). An axial SSFSE image through the right adnexa shows a paraovarian cyst with caliper measurements. The unremarkable right ovary is adjacent (arrows) with a follicle. c) and d) A 17-year-old girl with right lower quadrant pain. A coronal fat suppressed SSFSE image (c) through the left ovary shows multiple follicles. The region of interest to measure the T2 signal is placed within the parenchyma outside the follicles. The mean value indicated by the white arrow was used for T2 signal. An axial image from the apparent diffusion coefficient map series (d) was used to measure the diffusion with the region of interest outside any areas of hemorrhage if present. The reported mean value (white arrow) indicates the diffusion value.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/c7a45691d10fed8cd149c8dd.png"},{"id":66940681,"identity":"e7fc69c1-0e22-4bb4-a7b5-c1a817be7bd2","added_by":"auto","created_at":"2024-10-18 08:51:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":5383288,"visible":true,"origin":"","legend":"\u003cp\u003e14-year-old girl with right lower quadrant and periumbilical pain and emesis. a) This axial fat suppressed single shot fast spin echo (SSFSE) image shows the enlarged, very low, T2 signal left ovary (LO) with a large central complex cyst. Follicles are displaced to the periphery (thin arrows). The fallopian tube is thickened and twisted (open arrows). The right ovary is normal in size with intermediate T2 signal (arrowheads). B = bladder. b) An image at the same level as (a) from the apparent diffusion coefficient map series shows markedly restricted diffusion in the ovarian periphery/parenchyma and fallopian tube (heavy arrows). Restricted diffusion within the left ovarian cyst contents likely indicates hemorrhage (fine arrow). The right ovary (R) appears normal.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/d95bf4fce540bd1a56d308de.png"},{"id":66940680,"identity":"344c503d-3be8-430a-85af-8591933308fa","added_by":"auto","created_at":"2024-10-18 08:51:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":11402,"visible":true,"origin":"","legend":"\u003cp\u003eThis graph shows the volume of the larger adnexa for the torsed versus non-torsed groups. The heavy lines represent the median values for each group. The grey boxes represent the 25-75% values. The fine lines above and below the boxes represent the 95% and 5%, respectively. Although there is overlap with multiple large volume outliers in the non-torsed group, the median value for the torsed group was larger than the 95% value for the non-torsed group. (N = non-torsed, Y = torsed).\u003c/p\u003e","description":"","filename":"OnlineFig3.png","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/bd9206fb9d365dbb8ef8ae2c.png"},{"id":66941699,"identity":"5ef42114-333f-4b51-a2f5-174a75dc4993","added_by":"auto","created_at":"2024-10-18 08:59:05","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":11348,"visible":true,"origin":"","legend":"\u003cp\u003eThe volume ratio for the torsed versus non-torsed groups. The heavy lines represent the median values for each group. The grey boxes represent the 25-75% values. The fine lines above and below the boxes represent the 95% and 5%, respectively. There is overlap between the groups, but the median value for the torsed group was larger than the 95% value for the non-torsed group. Multiple high volume ratio cases occurred in the non-torsed group. (N = non-torsed, Y = torsed).\u003c/p\u003e","description":"","filename":"OnlineFig4.png","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/1c511d05c9dbb983c054b936.png"},{"id":66940686,"identity":"04a334d5-10f6-4a49-8d2c-27959fb9d272","added_by":"auto","created_at":"2024-10-18 08:51:05","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":4069740,"visible":true,"origin":"","legend":"\u003cp\u003eAn 18-year-old girl with right lower quadrant pain concerning for either appendicitis or ovarian torsion. Pelvic ultrasound performed within 24 hours prior to the MRI showed normal ovaries with a large right paratubal cyst. (not shown) a) An axial fat suppressed single shot fast spin echo image shows normal and symmetric appearing ovaries (arrows). C = paratubal cyst, B = bladder. b) An axial slice 2 cm cephalad to (a) demonstrate the large paratubal cyst that measured 8 cm in maximal diameter. Isolated right fallopian tube torsion was found at laparoscopy with normal ovaries, bilaterally.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/f08a575dad9438cdd6f3b686.png"},{"id":66941700,"identity":"81156402-4647-40db-bc3d-b106856643bf","added_by":"auto","created_at":"2024-10-18 08:59:05","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":880231,"visible":true,"origin":"","legend":"\u003cp\u003e13-year-old girl with right lower quadrant pain concerning for appendicitis. An axial fat suppressed single shot fast spin echo image through the ovaries shows asymmetric enlargement and increased T2 signal within the torsed right ovary (arrow). The left ovary is normal (open arrow). There is free fluid in the right pelvis (arrowheads).\u003c/p\u003e","description":"","filename":"OnlineFig6.png","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/5b395a25cb9777866acdf0ac.png"},{"id":66940683,"identity":"88eff8ff-e80b-46c8-9816-dfe0528a3541","added_by":"auto","created_at":"2024-10-18 08:51:05","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":8995,"visible":true,"origin":"","legend":"\u003cp\u003eThe T2 signal ratio for the torsed versus non-torsed groups. The heavy lines represent the median values for each group. The grey boxes represent the 25-75% values. The fine lines above and below the boxes represent the 95% and 5%, respectively. There is overlap between the groups with the median value for the torsed group falling above the 75%, but below the 95% for the non-torsed group. Multiple high T2 signal ratio cases occurred in the non-torsed group. (N = non-torsed, Y = torsed).\u003c/p\u003e","description":"","filename":"OnlineFig7.png","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/67bccf60d2d1c7ce5cdc8fab.png"},{"id":75351291,"identity":"bbc07c20-4da9-41cb-bbb6-2d4593205752","added_by":"auto","created_at":"2025-02-03 16:09:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":10440038,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4998787/v1/cf280dd1-5d65-4240-b0fb-71d86fd28e7e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Is a rapid MRI abdomen protocol for appendicitis useful for evaluation of ovarian torsion? ","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eIn females between 1 and 20 years of age, roughly 5 in 100,000 are affected by adnexal torsion [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Ovarian or adnexal torsion is reportedly found in 2.7% of females who had surgery for an acute abdomen [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Diagnosis of torsion is challenging because the signs and symptoms including nausea, vomiting, and persistent or colicky low abdominal pain that is often progressive and tender to palpation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan additionalcitationids=\"CR4 CR5 CR6 CR7\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] may be present in other conditions including acute appendicitis [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. As a result, only 30% of patients who undergo laparoscopy for suspected torsion are reported to have it [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. For the same reason, the diagnosis of torsion may be delayed, resulting in an ovarian salvage rate of 13.6\u0026ndash;27% [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDiagnostic laparoscopy is the gold standard for diagnosing adnexal torsion but is invasive and risky. Ultrasound is the most widely used modality for assessment of lower abdominal/pelvic pain and potential ovarian torsion because it is readily available, does not require ionizing radiation, and costs less than other cross-sectional imaging modalities [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Adequate adnexal evaluation with transabdominal technique requires a full bladder which may delay imaging while the bladder fills or require bladder catheterization if imaging cannot wait [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Even with a full bladder, imaging may still be suboptimal in patients with obesity. Transvaginal scanning is limited in the pediatric population to older teens who may be sexually active, or girls who use tampons or may have undergone intrauterine device (IUD) insertion. In addition to potential difficulty in getting an adequate pelvic sonogram, ultrasound criteria for the diagnosis of torsion are challenging as there may be overlap between torsed and untorsed ovaries [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Doppler signal evaluation may be confusing as some flow may be preserved in torsed ovaries [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan additionalcitationids=\"CR21 CR22\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. CT is infrequently used in this instance due to poor ovarian visibility and ionizing radiation. MRI also is infrequently utilized due to limited availability, cost, and exam duration.\u003c/p\u003e \u003cp\u003eWhen girls present with lower abdominal and pelvic pain, often there are multiple potential etiologies for that pain, including appendicitis or ovarian torsion [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Ultrasound remains the primary imaging for suspected ovarian torsion, but many girls present with less-specific lower abdominal or right lower quadrant pain and the working differential diagnosis for these patients includes both adnexal torsion and appendicitis. We sought to determine if there is a role for the rapid MRI scans performed frequently at our institution for appendicitis assessment in the evaluation of adnexal torsion. The exam duration is approximately 20 minutes and requires no sedation or IV contrast. We hypothesized that because the ovaries are visible in these images, assessing characteristics such as size, T2 signal, and diffusion would help distinguish normal from torsed adnexae.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003e Institutional Review Board approved this retrospective study of the records and imaging of girls aged 1\u0026ndash;19 who underwent limited MRI for appendicitis between 2013 and 2019. All reviews and data evaluation complied with HIPPA regulations. Informed consent was waived. Cases with incomplete MRI studies or non-visualization of one ovary were excluded as well as one transgender patient due to unknown hormonal status.\u003c/p\u003e \u003cp\u003eCases with surgically proven ovarian, adnexal (ovarian and tubal) or isolated tubal torsion were considered positive for torsion. Cases were considered negative for torsion if no torsion was found at surgery or if the discharge summary or emergency department (ED) disposition lacked mention or a diagnosis of ovarian, adnexal, or tubal torsion. The charts of all discharged patients without surgery were reviewed for an ED return within 48 hours. No patients who were initially discharged had a diagnosis of torsion upon ED return within 48 hours.\u003c/p\u003e \u003cp\u003eImaging was performed according to the standard departmental rapid protocol for suspected appendicitis. Studies were performed on any available MRI scanner, including both 1.5T and 3T units. Regardless of field strength, the protocol included a 3-plane single shot fast spin echo (SSFSE) localizer, coronal and axial non-fat saturated and fat-saturated T2-weighted SSFSE series and axial-diffusion-weighted imaging. All studies were performed without intravenous contrast.\u003c/p\u003e \u003cp\u003eThree experienced radiologists reviewed the MRIs and measured the ovarian diameters in all three planes (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). The size and location of ovarian or paratubal cysts were noted. Paratubal cysts that were clearly separate from the ovary were not included in ovarian measurements (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). Regions of interest were placed on T2-weighted SSFSE images in the brightest area of each ovary within stroma excluding follicles, cysts, or areas of hemorrhage similar to the method described by Kato et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Regions of interest also were placed in the darkest area of ovarian stroma excluding regions of hemorrhage on the apparent diffusion coefficient (ADC) maps (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). Calculations made from these measurements included larger to smaller ovarian volume ratios, stromal T2 signal ratios, and stromal ADC ratios.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eData Analysis\u003c/h2\u003e \u003cp\u003ePatient and clinical characteristics were summarized by the presence or absence of torsion. Continuous variables were summarized using mean (SD) or median (IQR) as appropriate, while categorical variables were summarized using frequencies and percentages. Continuous variables also were categorized at the median to describe the distribution of torsion above or below the median of study variables. This method ensures robustness to outliers. Two-sample t-tests or Mann-Whitney U tests were used to compare means or medians as appropriate. Univariable logistic regression was used to determine the association between torsion and study variables. A multivariable backward stepwise logistic regression was conducted to determine the variables substantially associated with torsion, with a cut-off point of p\u0026thinsp;=\u0026thinsp;0.10 to retain a variable in the model. Logistic regression and discriminant analysis were used to predict torsion using study variables. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were used to assess the predictive accuracy of study variables for predicting torsion. Model/test assumptions were checked, and appropriate measures were taken as needed. All tests were two-tailed with a significance level of 0.05. Statistical software R, version 4.3.2, was used for data analysis.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eWe identified 699 MRI scans performed with the appendicitis protocol for 667 girls with acute lower abdominal pain during the study period. Twenty-nine girls had the exam more than once during different ED visits in the study period, and one patient had 3 MRI scans. There were 653 complete examinations with ovaries visible bilaterally. One transgender patient undergoing hormonal therapy was excluded for concern of unpredictable hormonal influence on the ovaries. Two additional patients were excluded because the examination was performed for reasons other than acute lower abdominal/pelvic pain. Of the 650 patients included in the study, the median age was 13.5 years (range: 1.3\u0026ndash;19.6 years). Of the patients with proven torsion, the median age was 13.3 years (range: 6.4\u0026ndash;18.6 years). Sixty percent (n\u0026thinsp;=\u0026thinsp;390) of the patients were menarchal, 26% (n\u0026thinsp;=\u0026thinsp;168) were premenarchal, and 14% (n\u0026thinsp;=\u0026thinsp;90) had undocumented menstrual status. Indications for the MRIs included right lower quadrant pain, generalized or other abdominal pain, high clinical suspicion of appendicitis, and abnormal or nondiagnostic findings on prior ultrasound studies.\u003c/p\u003e \u003cp\u003eOne hundred twenty-one cases underwent a laparoscopic or open surgical procedure after MRI, with two additional patients having percutaneous drainage of abscesses due to perforated appendicitis. The prevalence of torsion, either adnexal or tubal in our overall population was 1.3% (n\u0026thinsp;=\u0026thinsp;8), with torsion identified in 6.5% of patients who went to surgery for either suspected torsion or suspected appendicitis. Ovarian torsion with or without associated adnexal torsion was identified and reduced laparoscopically in five patients (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The original MRI reports either described torsion or could not exclude torsion in all five cases of ovarian/adnexal torsion. Isolated tubal torsion without ovarian involvement was surgically reduced in three patients, with an associated paratubal cyst in all three cases. In these three cases, the original imaging reports correctly described the adnexal/paratubal cysts in each case but did not identify the isolated tubal torsion. In six other cases, the original MRI report raised a concern for ovarian torsion; however, no torsion was found for the two cases that went to surgery, one of which had an ovarian teratoma on the involved side, the other a ruptured hemorrhagic ovarian cyst. In the other four cases, one patient\u0026rsquo;s pain resolved, one patient was transferred to a general adult hospital with a diagnosis of pelvic inflammatory disease, and in two cases, a follow-up ultrasound was performed showing no findings concerning for ovarian/adnexal torsion. Five hundred nineteen cases did not require admission and were discharged (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Of these, 25 patients returned to the ED within 72 hours. No returning patients were subsequently diagnosed with adnexal or tubal torsion.\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\u003eFinal diagnoses of cases in our cohort\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiagnosis\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNumber of patients (n\u0026thinsp;=\u0026thinsp;650)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOvarian/adnexal torsion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIsolated tubal torsion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAppendicitis (acute or ruptured)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOvarian finding (teratoma, hemorrhagic cyst, ruptured follicle, dominant follicle)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e474\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e\u003csup\u003ea\u003c/sup\u003eOther includes nonspecific abdominal pain, constipation, inflammatory bowel disease, pelvic inflammatory disease, Mittelschmerz, gastroenteritis, and urinary tract infection.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eBilateral ovaries were measured in all cases. The average volume of untorsed adnexae was 8.25 mL (+/- 16.57) with a median of 5.89 mL (range 0.12\u0026ndash;510). The average volume of torsed adnexae was 188.16 mL (+/- 237 mL) with a median of 70.23 mL (range 12.13\u0026ndash;652.7; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). When evaluating the largest adnexal volume for each patient, there was a significant difference in the median largest volume for torsed adnexae (70.2 mL; Q1\u0026thinsp;=\u0026thinsp;27.8, Q4\u0026thinsp;=\u0026thinsp;268) and untorsed adnexae (7.91 mL; Q1\u0026thinsp;=\u0026thinsp;2.82, Q4\u0026thinsp;=\u0026thinsp;13.3; p\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) with overlap observed between groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). An adnexal volume greater than or equal to 20 mL had an 87.5% sensitivity for torsion, 89.5% specificity, 9.5% PPV and a 99.8% NPV.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe also assessed the ratio of adnexal volumes between the right and left sides. The median volume ratio of torsion cases was 9.57 (Q1 [25th percentile]\u0026thinsp;=\u0026thinsp;3.84, Q3 [75th percentile]\u0026thinsp;=\u0026thinsp;27.7). The median volume ratio of cases without torsion was 1.50 (Q1\u0026thinsp;=\u0026thinsp;1.23, Q4\u0026thinsp;=\u0026thinsp;2.21). Volume ratios in the torsed group were significantly higher than in the normal group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), although there was overlap (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). A volume ratio greater than or equal to 4.0 was 75% sensitive and 92% specific for torsion; however, this value had only an 11.5% PPV for ovarian/adnexal torsion. A volume ratio less than 4.0 had a 99.7% NPV.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSix of 650 cases had an ovarian or paratubal cyst 7 cm or greater, of which 83% (n\u0026thinsp;=\u0026thinsp;5) of the cases also had torsion. Six cases had cysts greater than or equal to 5 cm but less than 7 cm, only one of which also had torsion (17%). This case had a high adnexal volume ratio of 11.7. Two torsion cases had no cyst, but both had an ovarian volume ratio greater than 3. Both torsion cases that had an ovarian volume ratio less than 4 had an adnexal cyst greater than or equal to 7cm that was not included in the ovarian measurement (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). No torsion cases had normal-appearing adnexa on the involved side on MRI.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eT2 signal values tended to differ more between torsed and untorsed ovaries in the same patient than bilateral untorsed ovaries. The median T2 signal ratio comparing one ovary to the other in patients with torsion was 1.70 (Q1\u0026thinsp;=\u0026thinsp;1.34, Q4\u0026thinsp;=\u0026thinsp;2.23), which was significantly higher than in patients without torsion (1.21; Q1\u0026thinsp;=\u0026thinsp;1.09, Q4\u0026thinsp;=\u0026thinsp;1.40; p\u0026thinsp;=\u0026thinsp;0.01). This ratio included cases where the torsed ovary was either brighter or darker on T2-weighted images than the uninvolved ovary (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Although the T2 signal ratio difference between torsed and untorsed cases reached statistical significance, there was considerable overlap between the two groups due to outliers in the untorsed group (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The ADC value ratios for the torsed group tended to be larger than in the untorsed group but did not reach statistical significance. There were too few cases of torsion to separate premenarchal patients from post-menarchal patients for analysis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eUnivariable odds ratio analysis indicated vomiting, a volume ratio greater than 4, an adnexal volume of 20 mL or greater, and a cyst volume of 5 or larger, were all associated with increased odds of torsion (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). On multivariable logistic regression analysis only a large adnexal volume ratio contributed significantly to prediction of torsion with an odds ratio of 1.572, 95% confidence interval of 1.153\u0026ndash;2.197, p\u0026thinsp;=\u0026thinsp;0.006.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eUnivariable odds ratio for torsion\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eOdds Ratio\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLower\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUpper\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVomiting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.768\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.548\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e164.381\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVolume ratio (mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.157\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.466\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT2 signal ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.322\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.702\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiffusion ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.576\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.744\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLargest volume (mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.008\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.0003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLargest cyst measurement (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.152\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.837\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.716\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eOur evaluation of the limited abdominal pelvic MRI protocol used at our institution for assessment of suspected appendicitis found adnexal appearance does correlate with potential adnexal torsion. Normal adnexal size of less than 20 mL, symmetric adnexal volumes with a ratio less than 4, and the absence of a large adnexal cyst of 5 cm or more had a high NPV for torsion. Abnormal adnexal volume and volume ratio did not perform as well at predicting torsion.\u003c/p\u003e \u003cp\u003eMost imaging findings associated with adnexal torsion are non-specific and overlap with physiologic changes and non-surgical entities including enlargement and abnormal echogenicity of the involved ovary, involved ovarian position closer to the midline, shift of the uterus toward the affected side, fallopian tube thickening, and reduced, absent or abnormally high resistance vascular waveforms in the involved ovary [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan additionalcitationids=\"CR29 CR30\" citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Peripheral arrangement of follicles with follicular fluid/fluid levels, a follicular ring sign on ultrasound or MRI, a \u0026ldquo;whirlpool sign\u0026rdquo; of twisted adnexal vessels and a beaked appearance of the adnexal margin are specific findings but are not always seen, making imaging-based diagnosis of ovarian torsion difficult [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan additionalcitationids=\"CR30 CR31 CR32 CR33\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAsymmetric enlargement of the torsed adnexa has been described as a common finding [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], but is not always present [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan additionalcitationids=\"CR11 CR12 CR13\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan additionalcitationids=\"CR21 CR22\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. An adnexal volume less than 20mL had a 99.8% NPV for torsion in our cohort, similar to prior studies in menarchal girls [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. An adnexal volume greater than or equal to 20 mL was 87.5% sensitive and 89.5% specific for torsion and was associated with increased odds of torsion. A volume ratio less than 4 had a very high NPV of 99.7% for torsion. The PPV of MRI for torsion based on volume ratio was poor at 11.5%; however, it had a moderate sensitivity and good specificity at 75% and 92%, respectively. There were 67 non-torsion cases with adnexal volumes over 20 mL and 46 cases with adnexal volume ratios greater than 4 that may have had physiologic ovarian enlargement due to recent follicular rupture, hemorrhagic cysts, pelvic inflammatory disease or a corpus luteum. As has been previously reported [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], we found that an asymmetrically enlarged ovary is concerning because of increased odds for torsion but has a low PPV for torsion when considered alone.\u003c/p\u003e \u003cp\u003eThe T2 signal of torsed ovaries tended to differ from normal ovaries. On T2-weighted images, torsed ovarian signal can be higher than the unaffected ovary due to stromal edema from venous congestion soon after torsion or darker than the normal ovary from infarct or hemorrhage after more prolonged torsion [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan additionalcitationids=\"CR39 CR40 CR41 CR42 CR43\" citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. The ratio of signal intensities did reach statistical significance in our analysis; however, the values overlapped a great deal with normal patients \u0026ndash; more so than the volume ratios. Variation in ovarian signal on a physiological basis or due to pathology other than torsion can appear similar to the signal differences associated with torsion [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. T2 signal ratios in our study overlapped between groups with and without torsion. Due to the small number of torsion cases, we could not evaluate a combined predictive value of the volume and T2 signal ratios. The ADC ratio values had the greatest amount of overlap between groups and did not reach statistical significance. This is contradictory to previously reported differences in ADC values for torsed and non-torsed ovaries [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e], possibly due to the lower resolution, rapid MRI protocol used in our study population with decreased spatial resolution. More study is needed in this area.\u003c/p\u003e \u003cp\u003eIn our population, we encountered adnexal torsion prevalence of 1.3%, with torsion present in 6.5% of patients who went for surgery, which was higher than the 2.7% reported by Hibbard [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]; although their population included patients of all ages. Our study was retrospective and patients with a high suspicion of adnexal torsion based on clinical or pelvic ultrasound findings would not have undergone the MRI for appendicitis imaging. For this reason, additional study is needed to assess the performance of MRI in patients with a higher pretest probability of torsion as well as in a cohort with a larger number of torsion cases to improve the statistical analysis. Additionally, our specificity for torsion prediction was significantly less than that reported in pregnant patients by Lee et al. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]; however, this may be due to the lower resolution, rapid MRI technique evaluated in our study.\u003c/p\u003e \u003cp\u003eBoth false negative cases that had a volume ratio less than 4, and the false negative case with an ovarian volume less than 20 mL, involved isolated tubal torsion with large paratubal cysts and normal ovaries. The ovarian volume ratios and ovarian volume for these cases were low because the ovaries were not torsed and, therefore, were unenlarged and the paratubal cysts were not included in the adnexal volume measurements. A normal appearing ovary in the instance of isolated tubal torsion has been previously reported [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan additionalcitationids=\"CR47 CR48\" citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]. On ultrasound, adnexal structures may be difficult to differentiate and a paratubal cyst may appear to arise from the ovary, and would, therefore, be included in the adnexal measurement [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. In some of our cases, the MRI appearance of the adnexa permitted distinction of the paratubal cysts from the ovaries due to improved definition of soft tissue structures. In comparison, the diameter of a normal fallopian tube should be less than or equal to 1 cm [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. These cases emphasize the presence of large paratubal cysts or other lesions and should be considered as paratubal abnormalities and tubal dilatation have been described as being lead points for both adnexal and isolated tubal torsion [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs this study was retrospective in nature, ovarian sizes and volumes were not reported on the initial interpretations; adnexal cysts or lesions or abnormal adnexal appearance were reported. Imaging techniques varied slightly across cases due to differences in scanner platforms and field strengths. This variability may underscore the reliability of our findings across MRI protocols. We assumed patients did not have torsion if torsion was not diagnosed at the initial visit and the patient did not return within 72 hours. We may have missed patients who sought care at another institution after their initial discharge. No patients who returned were subsequently diagnosed with torsion. Lastly, we had a small number of torsion cases, which almost certainly affected the statistical analysis. Normal ovarian volumes in the presence of adnexal torsion have been reported, particularly in younger girls [7,16,20,]. No patients with torsion of the ovary or ovary and fallopian tube in our cohort had a normal or symmetric adnexal volume. Linam et al. reported differences in adnexal volumes for premenarchal versus post-menarchal patients with torsion [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]; however, our cohort included only two premenarchal patients with torsion, preventing separate analyses of the two developmental groups.\u003c/p\u003e \u003cp\u003eFurther study is required to prospectively assess the efficacy of MRI for exclusion of adnexal torsion, particularly in a population who may have a higher prevalence of torsion, a larger number of cases with torsion, and a larger representation of premenarchal versus menarchal girls. Further investigation of rapid protocol MRI as a primary imaging modality for differential diagnosis of appendicitis versus ovarian torsion in girls presenting to the ED is required. MRI as a primary modality may prove useful for contributing to a combined imaging and clinical scoring system for predicting ovarian torsion, which would improve diagnosis of the uncommon torsion patients without ovarian enlargement [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e], but prospective study is needed.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eA short, non-contrast MRI protocol used for evaluation of acute appendicitis is reliable for excluding adnexal torsion in patients who do not have high clinical or ultrasound suspicion for torsion and who have symmetric appearing adnexae with no large adnexal cysts measuring greater than 5 cm. More study is needed to confirm these findings in patients who may have a higher pretest probability of torsion. Ultrasound remains the primary tool for patients with a high suspicion of torsion due to its greater availability and lower cost.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualization: Sharon Gould, Arvind Choudhary; Methodology: Sharon Gould, Arvind Choudhary, Heidi Kecskemethy; Formal analysis and investigation: Sharon Gould, Tejal Mody, Arvind Choudhary, Simone Veale, Mary Gould; Writing - original draft preparation: Sharon Gould; Writing - review and editing: Sharon Gould, Heidi Kecskemethy, Tejal Mody, Arvind Choudhary; Resources: Sharon Gould, Heidi Kecskemethy; Supervision: Sharon Gould, Heidi Kecskemethy.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eSimone Veale and Mary Gould were supported by the Nemours Departments of Biomedical Research (through the Nemours Summer Undergraduate Research Program) and Medical Imaging.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data that support the findings of this study are not openly available due to HIPAA privacy protection and are available from the corresponding author upon reasonable request after de-identification.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAdnexal Torsion in Adolescents (2019) ACOG Committee Opinion No, 783. 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Pediatr Radiol 46:928\u0026ndash;939\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKato H, Kanematsu M, Uchiyama M, Yano R, Furui T, Morishige K (2014) Diffusion-weighted imaging of ovarian torsion: usefulness of apparent diffusion coefficient (ADC) values for the detection of hemorrhagic infarction. Magn Reson Med Sci 13:39\u0026ndash;44\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGraif M, Shalev J, Strauss S, Engelberg S, Mashiach S, Itzchak Y (1984) Torsion of the ovary: sonographic features. AJR Am J Roentgenol 143:1331\u0026ndash;1334\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKimura I, Togashi K, Kawakami S, Takakura K, Mori T, Konishi J (1994) Ovarian torsion: CT and MR imaging appearances. Radiology 190:337\u0026ndash;341\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIraha Y, Okada M, Iraha R et al (2017) CT and MR Imaging of Gynecologic Emergencies. Radiographics 37:1569\u0026ndash;1586\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee JH, Roh HJ, Ahn JW et al (2020) The Diagnostic Accuracy of Magnetic Resonance Imaging for Maternal Acute Adnexal Torsion during Pregnancy: Single-Institution Clinical Performance Review. J Clin Med 9:2209\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSibal M (2012) Follicular ring sign: a simple sonographic sign for early diagnosis of ovarian torsion. J Ultrasound Med 31:1803\u0026ndash;1809\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGhossain MA, Hachem K, Buy JN et al (2004) Adnexal torsion: magnetic resonance findings in the viable adnexa with emphasis on stromal ovarian appearance. J Magn Reson Imaging 20:451\u0026ndash;462\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePetkovska I, Duke E, Martin DR et al (2016) MRI of ovarian torsion: Correlation of imaging features with the presence of perifollicular hemorrhage and ovarian viability. Eur J Radiol 85:2064\u0026ndash;2071\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuchon C, Fauconnier A (2010) Adnexal torsion: a literature review. Eur J Obstet Gynecol Reprod Biol 150:8\u0026ndash;12\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e\u0026Ouml;zdemir O, Metin Y, Metin NO, K\u0026uuml;peli A (2017) Contribution of diffusion-weighted imaging to conventional MRI for detection of haemorrhagic infarction in ovary torsion. BMC Med Imaging 17:56\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchwartz BI, Huppert JS, Chen C, Huang B, Reed JL (2018) Creation of a Composite Score to Predict Adnexal Torsion in Children and Adolescents. J Pediatr Adolesc Gynecol 31:132\u0026ndash;137\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYamashiro T, Inamine M, Kamiya H, Kinjo A, Murayama S, Aoki Y (2008) Massive ovarian edema with torsion: unusual hemorrhage and the recovery of contrast enhancement. Emerg Radiol 15:115\u0026ndash;118\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRha SE, Byun JY, Jung SE et al (2002) CT and MR imaging features of adnexal torsion. Radiographics 22:283\u0026ndash;294\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTrindade RM, Baroni RH, Rosemberg M et al (2010) Magnetic resonance imaging findings in adnexial torsion. Einstein (Sao Paulo) 8:92\u0026ndash;96\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLourenco AP, Swenson D, Tubbs RJ, Lazarus E (2014) Ovarian and tubal torsion: imaging findings on US, CT, and MRI. Emerg Radiol 21:179\u0026ndash;187\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDahmoush H, Anupindi SA, Pawel BR, Chauvin NA (2017) Multimodality imaging findings of massive ovarian edema in children. Pediatr Radiol 47:576\u0026ndash;583\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBader T, Ranner G, Haberlik A (1996) Torsion of a normal adnexa in a premenarcheal girl: MRI findings. Eur Radiol 6:704\u0026ndash;706\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJain KA (1995) Magnetic resonance imaging findings in ovarian torsion. Magn Reson Imaging 13:111\u0026ndash;113\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVan Kerkhove F, Cannie M, Op de Beeck K et al (2007) Ovarian torsion in a premenarcheal girl: MRI findings. Abdom Imaging 32:424\u0026ndash;427\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBekci T, Polat AV, Aslan K, Tomak L, Ceyhan Bilgici M, Danaci M (2016) Diagnostic performance of diffusion-weighted MRI in the diagnosis of ovarian torsion: comparison of torsed and nonaffected ovaries. Clin Imaging 40:1029\u0026ndash;1033\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGross M, Blumstein SL, Chow LC (2005) Isolated fallopian tube torsion: a rare twist on a common theme. AJR Am J Roentgenol 185:1590\u0026ndash;1592\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePropeck PA, Scanlan KA (1998) Isolated fallopian tube torsion. AJR Am J Roentgenol 170:1112\u0026ndash;1113\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOrazi C, Inserra A, Lucchetti MC, Schingo PM (2006) Isolated tubal torsion: a rare cause of pelvic pain at menarche. Sonographic and MR findings. Pediatr Radiol 36:1316\u0026ndash;1318\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCasey RK, Damle LF, Gomez-Lobo V (2013) Isolated fallopian tube torsion in pediatric and adolescent females: a retrospective review of 15 cases at a single institution. J Pediatr Adolesc Gynecol 26:189\u0026ndash;192\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBack SJ, Merrow AC (2016) Case 4: an adolescent girl with left lower quadrant pain. Pediatr Radiol 46:1068\u0026ndash;1074\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"pediatric-radiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prad","sideBox":"Learn more about [Pediatric Radiology](http://link.springer.com/journal/247)","snPcode":"247","submissionUrl":"https://submission.nature.com/new-submission/247/3","title":"Pediatric Radiology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Ovary, torsion, pediatric, MRI, adnexa","lastPublishedDoi":"10.21203/rs.3.rs-4998787/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4998787/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eDiagnosis of adnexal torsion is challenging as presentation and imaging findings are non-specific.\u003c/p\u003e\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eEvaluate an MRI appendicitis protocol for adnexal torsion identification and determine if torsion can be excluded by limited abdominopelvic MRI.\u003c/p\u003e\u003ch2\u003eMaterials and methods\u003c/h2\u003e \u003cp\u003eThis retrospective study of females ages 1\u0026ndash;19 who had limited abdominal MRI exams between 2013 and 2019. Radiologists measured ovaries and calculated ovarian volume ratios, stromal T2 signal ratios, and stromal ADC ratios. Adnexal cysts\u0026rsquo; size, location, and relationship to the ovary were noted.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOf 699 cases, 650 were included. Eight cases had surgically proven torsion. Significantly higher volume ratios were found in torsed cases (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). A volume ratio greater than or equal to 4:1 had 75% sensitivity, 92% specificity, and 11.5% positive predictive value. A volume ratio less than 4:1 had 99.7% negative predictive value. Ovarian volumes greater than or equal to 20 mL had 87.5% sensitivity, 89.5% specificity, and 9.5% positive predictive value. A volume less than 20 mL had 99.8% negative predictive value. Four torsion cases had cysts greater than or equal to 5cm, including 2 cases without elevated ovarian volume ratio. Four of 5 cases with cysts greater than 7cm were torsed. Stromal T2 signal ratios for torsed cases were higher than non-torsed cases (p\u0026thinsp;=\u0026thinsp;0.01). Stromal ADC ratio differences did not reach statistical significance (p\u0026thinsp;=\u0026thinsp;0.46).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThere was a 1.3% prevalence of torsion. Two cases were not detected by ovarian size or volume ratio but had large paratubal cysts. No torsion cases had normal appearing adnexa.\u003c/p\u003e","manuscriptTitle":"Is a rapid MRI abdomen protocol for appendicitis useful for evaluation of ovarian torsion? 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