Struma ovarii: MRI findings

We describe the MRI findings in three cases of struma ovarii. In all three cases, MRI showed a multilocular cystic mass with a variable signal intensi ty within loculi. Some loculi or small cysts within septations showed low s ignal intensity on T-1 weighted images and very low signal intensity on T-2 weighted images, corresponding pathologically to gelatinous colloid materi al in large follicles. In one case, with Gd-DTPA enhanced T-1 weighted imag es, the thick septations and locally thickened wall showed marked enhanceme nt, corresponding microscopically to thyroid tissue.