MR Imaging of the Thyroid

Abstract

Spin-echo magnetic resonance (MR) imaging of the thyroid gland was performed in patients using a superconducting magnet operating at 0.35 T. There were 17 women and two men with an age range of 21-77 years. All of the patients with disease were also evaluated with scintigraphy and three of the four subjects with normal thyroid glands also had scintigraphy. Final diagnoses in the patients were normal gland in four, Graves disease in two, thyroid cyst in one, benign follicular adenoma in two, papillary cell carcinoma in one, Hürthle cell carcinoma in one, Hashimoto thyroiditis in one, and multinodular goiter in seven. The normal thyroid and surrounding anatomy were clearly demonstrated by intrinsic signal intensity differences of the tissues. The thyroid gland in Graves disease was enlarged and had homogeneously increased signal intensity at all pulse sequences compared with skeletal muscle and normal thyroid. The thyroid cyst and benign adenoma were well defined; however, the cyst displayed the greater signal intensity on more T2-weighted pulse sequences. The MR signal intensity features of multinodular goiter and Hashimoto thyroiditis appear similar to those of the normal gland. In cases of focal masses, MR could not reliably distinguish benign from malignant tumor. However, using intensity ratio data there was a statistically significant difference between solid and hemorrhagic cystic disease.