[Adrenal myelolipomas: their magnetic resonance assessment]

Adrenal myelolipomas are rare nonfunctioning neoplasias consisting of a variable mixture of mature fat and bone marrow tissue. In the present study MRI appearances of six adrenal myelolipomas are presented. MR exams of six patients in which a conclusive diagnosis of adrenal myelolipomas was reached by means of surgery (1 case), US-guided fine-needle biopsy (3 cases) and typical diagnostic imaging in association with stability on US follow-up for at least two years (2 cases) were retrospectively evaluated. MR sequences protocol included pre- and post-contrast (Gd-DTPA) SE T1-weighted images and SE proton density and T2-weighted images. Five adrenal masses were examined by means of combination of gadolinium administration with a SE T1-weighted modified three-point Dixon technique. Three different MR structural patterns were pointed out: a) homogeneous hyperintense masses on T1-weighted images with intermediate signal on T2-weighted images, suggestive for predominantly fat-containing lesions (2 cases); b) heterogeneous masses with fat intensity areas and hyperintense areas on T2-weighted images and on post-contrast T1-weighted images, suitable for mixed fatty and myeloid elements (2 cases); c) nodules hypointense to the liver on T1-weighted images and hyperintense on T2-weighted images and after gadolinium administration, suggesting tumors primarily composed of myeloid cells (2 cases). A precise determination of fatty and myeloid elements within the lesions was observed by means of "water" and "fat" images provided by modified three-point Dixon technique. In conclusion, MRI allows to determine the various structural components of myelolipomas and therefore appears to be a very reliable technique in the diagnosis and characterization of the different structural patterns of this rare adrenal pathology.