MR findings of struma ovarii.

This study was performed to characterize MR findings of struma ovarii. In 10 patients, T1- and fast spin echo T2-weighted MR images were obtained in the axial, coronal, and sagittal planes using 1.5 T MR units, and they were retrospectively evaluated for the site, size, components, signal intensity, and contrast enhancement.MR images showed a unilateral complex mass with a multilobulated surface and thickened septa, corresponding pathologically to thyroid follicles and the stroma. Cystic portions had variable signal intensities on T1- and T2-weighted images. The contents of cystic components showing low signal intensities both on T1- and T2-weighted images were viscid gelatinous materials (n=4). Solid portions were relatively well-enhanced. In conclusion, struma ovarii has some characteristic MR appearance of a multilobulated complex mass with thickened septa, multiple cysts of variable signal intensities, and enhancing solid components.