Preoperative magnetic resonance evaluation of Struma Ovarii and its importance for the surgical modality: a retrospective study from two institutions.

Objectives: To improve preoperative diagnostic accuracy of struma ovarii by retrospectively reviewing magnetic resonance (MR) findings. It is beneficial to choose the most appropriate surgical modality for the patient.

Methods: We retrospectively reviewed the clinical course and MR characteristics of 52 patients who were diagnosed postoperatively with struma ovarii, pathologically, from two institutions. All patients were performed routine and contrast enhanced MR scans.

Results: All tumors were unilateral. Forty- eight tumors (92.3%) were multicystic with variable signal intensity. On T2-weighted images, some loculi or small cysts with very low signal intensity were recognized in forty-two tumors (80.8%). The solid part of the tumor was significantly enhanced on T1-weighted enhanced image in forty-two cases (80.8%), without diffusion restriction in forty-one cases (97.6%). Diffusion restriction was observed in only one patient (2.4%). Laparoscopic surgery was performed in 32 patients (61.5%) whose preoperative diagnosis was benign or borderline. The rest 20 cases (38.5%) underwent exploratory laparotomy, including 14 cases with malignant diagnosis, 5 cases of mucinous cystadenoma and a case of giant serous cystadenoma.

Conclusion: A mass composed of multiple cysts with variable signal intensity, some loculi or small cysts with very low signal intensity on T2-weighted image and the solid part of the tumor significantly enhanced on T1-weighted enhanced image without diffusion restriction are appeared to be the characteristic MR findings of struma ovarii. Accurate preoperative diagnosis of struma ovarii is beneficial to choose the most appropriate surgical approach for the patient.