Chemical Shift MR Imaging of Adrenal and Renal Masses.

Chemical shift MR imaging uses two echo times to exploit differences in fat and water proton precessional frequencies. When both fat and water are present in the same voxel, signal loss occurs on out-of-phase images compared to in-phase images, indicating microscopic fat. In adrenal masses, the detection of microscopic fat can aid in differentiating benign lipid-rich adrenal adenomas from other adrenal masses. In the kidneys, microscopic fat may be seen in fat-poor angiomyolipomas and clear cell renal cell carcinomas, which is uncommon in other renal tumors. Additional MR imaging features may be used to differentiate between these two diagnoses.