Role of MRI in diagnosis of adrenal tumors

: The authors evaluated the ability of magnetic resonance imaging (MRI) at 1.5 T to characterize 33 adrenal masses, using visual analysis and the following quantitative variables: signal intensity ratios of tumor/liver, tumor/muscle, and (tumor--muscle)/(fat--muscle) on T2- and T1-weighted images, and the calculated T2 relaxation time of the adrenal masses. All 15 tumors of less than 3 cm in diameter were visually homogeneous on all pulse sequences, whereas the other 18 tumors of over 3 cm appeared to be inhomogeneous. The signal intensity ratios of tumor/liver and tumor/muscle and the calculated T2 relaxation time were not helpful in distinguishing tumors from one another. The ratios of tumor/fat and (tumor--muscle)/(fat--muscle) were useful in distinguishing pheochromocytoma and myelolipoma from other tumors on T2- and T1-weighted images, respectively. However, differentiation among other adrenal tumors appeared to be difficult. The authors concluded that, although MRI might have considerable potential in characterizing adrenal masses, the use of conventional MRI in such analysis is still quite limited.