[Role of MR in characterizing expansive lesions of the adrenal gland].

Five patients with adrenal tumors (20 metastases, 12 adenomas, 8 myelolipomas, 6 primary tumors, 4 pheochromocytomas, and 1 hyperplasia) were studied by means of MRI with SE sequences. Twenty of them underwent dynamic study with GE sequences after i.v. injection of paramagnetic contrast media. Sixteen of 20 metastases exhibited low signal intensity on T1 and high signal on T2. One patient had low signal on both T1 and T2. Two lesions in patients with melanoma showed high signal in T1; in 1 case, the lesion exhibited a hemorrhagic area. Signal from adenomas was low in T1- and T2-weighted pulse sequences in 10/12 patients, while in the extant 2 cases signal was higher in T2. Myelolipomas had hyperintense signal on T1-weighted images in 5 cases and isointense signal with the renal cortex in the extant 3 cases. Pheochromocytomas and primary tumors appeared hypointense on T1 and hyperintense on T2. In 3 CT questionable cases, MRI showed the adrenal origin of the lesion. Dynamic study with GE sequences after Gd-DTPA injection showed low enhancement and fast washout in adenomas, while malignant lesions had higher enhancement and slower washout. In our study, MRI allowed to correctly characterize 11/12 adenomas, with only 1 false negative in a metastatic lesion.