Adrenal gland: MR imaging

The authors investigated the utility of magnetic resonance (MR) imaging in identifying the normal adrenal gland in 100 patients as well as in distinguishing adrenal adenomas (n = 12) from malignant neoplasms (n = 14). The left adrenal gland was seen in 99 of 100 cases and the right in 91 of 100 cases. The adrenals were most easily seen with T1-weighted spin-echo pulse sequences. The ratio of the intensity of the adrenal mass to that of fat at 2,100/90 (repetition time msec/echo time msec) was most helpful in distinguishing adrenal adenomas from malignant neoplasms. In contrast to other studies, the adrenal mass/liver intensity ratios were not helpful. All ten lesions with adrenal mass/fat ratios at 2,100/90 of 0.8 or greater were malignant, whereas all eight adrenal masses with a ratio less than 0.6 were adrenal adenomas. However, eight (31%) of the masses (four adenomas and four malignant neoplasms) had ratios between 0.6 and 0.8. Although MR imaging has considerable potential in characterizing adrenal masses, larger studies are needed to determine its true sensitivity and specificity.