Rapid, free-breathing non-contrast MRI for first-line imaging evaluation of ovarian torsion in the emergency department

Abstract

Background: Transabdominal ultrasound (US) is first-line imaging to evaluate ovaries in girls presenting to the emergency department (ED) with suspected ovarian torsion. Ovaries may be difficult to visualize sonographically; therefore, prompt diagnosis using US alone can be challenging. Rapid MRI as first-line imaging may help streamline patient throughput, especially with increasing MRI availability in the ED.

Objective: To assess feasibility of rapid MRI for diagnosis of ovarian torsion.

Materials and methods: A retrospective, single-center IRB approved study of MRI performed in female pediatric patients presenting with abdominopelvic pain from August 2022 to January 2023. Imaging occurred according to one of three clinical pathways (US-first approach vs MRI-first approach vs US + MRI-second-line approach). A rapid three-sequence free-breathing MRI protocol was utilized. Frequency of ovarian torsion and secondary diagnoses was recorded. Length of MR scan time, time from ED arrival to time of diagnosis, and whether patient had US prior to MR exam were obtained. A historical cohort of patients with US only performed for assessment of ovarian torsion were evaluated for length of the US examination and time from ED arrival to time of diagnosis. Intervals were compared using the uncorrected Fisher's least significant difference and Turkey's multiple comparison tests.

Results: A total of 140 MRI exams (mean age 14.6 years) and 248 historical US exams (mean age 13.5 years) were included. Of the patients with MRI, 41 (29%) patients were imaged with US + MRI and 99 (71%) imaged with MRI only; 4% (6/140) MR exams were suspicious for ovarian torsion, with one true positive case (1/6 TP) and 5 false positive cases (5/6 FP); 26.4% (37/140) of exams had secondary diagnoses. Median MRI scan time was 11.4 min (4.4) vs median historical US scan time was 24.1 min (19.7) (P<0.001). Median time from arrival in ED to MRI read was 242 (140). Median time from arrival in ED to US only read was 268 min (148). This was not a statistically significant difference when compared to the MRI only cohort.

Conclusion: First-line MRI imaging for evaluation of ovarian torsion is a rapid and feasible imaging modality for female patients in the emergent setting.

Keywords: Emergency; MRI; Ovarian; Pediatric; Torsion.