MR imaging of adrenal myelolipomas

The magnetic resonance (MR) images in six patients with seven adrenal myelolipomas are presented. Four lesions involved the right gland, and three the left; they ranged from 3 to 12.5 cm in diameter. Magnetic resonance was able to image all lesions. Using T1-weighted sequences, three structural patterns were observed; (a) homogeneous masses with intensity equal to adjacent fat (three cases); (b) heterogeneous masses with fat intensity areas and areas similar to renal cortex (two cases); and (c) nodules quite different from fat, hypointense to the liver (two cases). On T2-weighted images, myelolipomas were slightly hypointense to fat and either hypo- or isointense to the liver. A comparison with the results of CT studies was possible in all cases, and good correlation with determination of the presence and quantity of fat density tissues within the lesions was observed. However, MR imaging did not seem to help in diagnosing adrenal myelolipoma in patients with equivocal CT findings, and needle biopsy is still needed in difficult cases.