Diagnosis of adrenal adenoma: Value of central spot of high-intensity hyperintense rim sign and homogeneous isointensity to liver on gadolinium-enhanced fat-suppressed spin-echo MR images

Eighty-nine patients with 108 adrenal masses, either adenomas (n = 88) or m alignant lesions (n = 20), underwent magnetic resonance imaging (MRI) of th e abdomen at 0.5 T for the purpose of determining whether adrenal adenomas could be differentiated from malignant lesions on gadolinium-enhanced fat-s uppressed T1-weighted spin-echo (SE) images (Gd-E FS T1WI) and on T2-weight ed SE images. The imaging protocol included conventional unenhanced SE T1- and T2-weighted sequences and Gd-E FS T1WI, Three observers independently e valuated signal intensity on unenhanced and enhanced images and also the pr esence of structures of high signal intensity in the outer margin [hyperint ense rim sign (HRS)] or in the center [hyperintense central spot (HCS)] of the adrenal masses. Forty-one (46.5%) of 88 adenomas were homogeneously iso intense to liver in unenhanced and enhanced T1-weighted sequences and in T2 WI, HCS and HRS were observed in 33/88 (37.5%) and 15/88 (17%) adenomas, re spectively, on Gd-E FS T1WI: in contrast, these signs were never revealed i n any case of malignant lesions. Sensitivity, specificity, positive predict ive value, negative predictive value, and overall accuracy in classifying l esions as suggestive of adenoma were 93%, 90%, 98%, 75%, and 93%, respectiv ely, Visual evaluation of details of tumor structures on Gd-E FS T1WI allow s good characterization of adrenal masses. HCS, HRS, and homogeneous isoint ensity to liver are characteristic signs of adrenal adenomas, J. Magn. Reso n. Imaging 1999;9:304-310. (C) 1999 Wiley-Liss, Inc.