Figure 8a. Hemorrhagic renal mass manifesting as acute right flank pain during the second trimester. US showed an echogenic mass, but the origin of the mass (adrenal vs renal) and its composition (fat vs hemorrhage) could not be determined. (a) Coronal T1-weighted gradient-echo image shows a heterogeneous mass with areas of high signal intensity (arrow) originating from the upper pole of the right kidney. (b) Coronal T1-weighted gradient-echo image obtained with fat suppression shows persistent bright areas (arrows), which represent hemorrhage, and a central dark area (arrowhead), which represents fat within the lesion. This case demonstrates the usefulness of multiplanar imaging and the ability of MR imaging to allow differentiation between fat and hemorrhage. The patient was treated conservatively and successfully gave birth but was lost to follow-up for 2 years. When she returned for evaluation of a subsequent pregnancy, repeat MR imaging showed no interval growth of the mass (which was interpreted as an angiomyolipoma) and complete resolution of the hemorrhage.