[MR imaging of thyroid masses].

Magnetic resonance (MR) imaging was performed in 35 patients with histologically proved thyroid masses. Gadopentetate dimeglumine was used in 25 of these cases. The thyroid tumors were analyzed by MR imaging as to shape, margin, pseudocapsulation, homogeneity, and enhanced pattern. Gd-DTPA was helpful in identifying pseudocapsules and showing the extent of the tumor. Papillary carcinoma tended to display unclear margins, heterogeneous intensity, and inhomogeneously enhanced patterns. In follicular adenoma, the tumor margin was smooth and pseudocapsules were clearly detected. Follicular adenoma was enhanced homogeneously, but it was difficult to distinguish follicular adenoma from follicular carcinoma by MR imaging. Adenomatous goiter was delineated as multiple nodules with smooth margins, but without pseudocapsules. These nodules were enhanced in various ways after Gd-DTPA administration.