Normal ovarian sizes on MRI in pediatric patients: a preliminary study

Background Ovarian enlargement is one of several findings of pathology, including ovarian torsion. With increasing use of MRI for acute abdominal pain in children, data for normal ovary size and appearance are needed. Objective To provide preliminary data on normal sizes of ovaries on MRI in pediatric patients. Materials and methods This retrospective IRB-approved study included girls (5 to 17 years of age) with MRI examinations performed for indications not related to the ovaries from 2018 to 2022. For each MRI, coronal T2-weighted single shot fast spin echo and axial T2-weighted fat-saturated images were independently reviewed by three pediatric radiologists who recorded ovary visualization and ovarian linear measurements (3 planes). Ovarian volumes were calculated from linear measurements. Agreement among observers was calculated using kappa statistics and intraclass correlation coefficients. Results A total of 181 MRIs were reviewed. The left ovary was visualized in 166–176 (92–97%) cases (R1–R3) and the right ovary was visualized in 165–174 (91–96%) cases with excellent agreement among reviewers (left: K = 0.89 [0.84–0.94], right: K = 0.85 [0.79–0.91]). Interrater class coefficient (ICC) for largest single dimension of the ovary was left: 0.83 (CI 0.79–0.87) and right: 0.85 (CI 0.81–0.89). There were significant moderate to strong correlations between ovarian volume and age (left: 0.67 [0.58–0.75], right: 0.66 [0.57–0.74]). Conclusion The ovaries can be adequately visualized and measured on MRI with excellent inter-reader agreement. This study serves as the foundation for developing normative values for ovarian volumes by age on MRI. Graphical Abstract