Rapid abdominal MRI for appendicitis for evaluation of ovarian torsion in children.

Purpose: Diagnosing adnexal torsion is challenging due to non-specific presentation and ultrasound findings. MRI may provide alternative assessment of adnexal torsion. We evaluated an MRI appendicitis protocol for torsion identification.

Methods: Retrospective chart and image review was performed for girls with appendicitis MRI exams from 2013 to 2019. Ovarian volumes, stromal T2 signal, and apparent diffusion coefficient (ADC) ratios were tabulated. Ovarian and paratubal cysts' size and location were recorded as well as presence or absence of torsion. Statistical analysis was performed.

Results: Six hundred-fifty cases were included, eight with torsion. Higher ovarian volumes and volume ratios were found with torsion (p < 0.0001 and p < 0.0001, respectively). Ovarian volume ratio less than 4:1 had 99.7% negative predictive value (NPV). Ovarian volume less than 20 mL had 99.8% NPV. Five of six cases with 7 cm or larger adnexal cysts were torsed. T2 signal and ADC ratios overlapped between torsed and untorsed groups. No torsed adnexa appeared normal on MRI.

Conclusion: Torsed cases tended to have larger ovaries and higher volume ratios. Adnexal cysts greater than 7 cm diameter were likely to be torsed. No torsion cases had normal adnexae on MRI. Normal appearing adnexae on MRI are very unlikely to be torsed.