Chemical shift GRE MRI of renal angiomyolipoma.

The renal angiomyolipoma is a fairly common benign renal tumor composed of various proportions of smooth muscle, blood vessels, and fat. Because fat is present in virtually every case, the CT findings in angiomyolipomas are so distinctive that a histologic diagnosis may be suggested. In angiomyomas composed mainly of vascular tissue and muscle or in those in which recent hemorrhage has occurred, the majority of tumors may have soft tissue CT density values without apparent fatty component (1,2). In such cases, preoperative diagnosis is extremely difficult. In this case report, we detected a small amount of fatty tissue with a chemical shift GRE MRI technique, although CT failed to detect the fatty tissue.