Hepatic angiomyolipoma: MRI findings

Objective: To analyze the variable appearances of hepatic angiomyolipoma (AML) on the magnetic resonance imaging (MRI), and to improve the diagnostic accuracy of AML with MRI. Methods and materials: Twelve cases were proved by surgical pathology. MRI with SE T1WI, FSE T2WI and FMPSPGR axial dynamic multi-phase contrast scanning were performed in all cases. Results: Eight of ten lesions showed inhomogeneous hyperintense on SE T1WI and the part of hyperintensity turned to hypointensity with the application of fat suppression technique. The other four lesions were hypointense. Flow void signal could be seen in four lesions. Ten lesions were various hyperintensity from slight hyperintensity to strong hyperintensity on FSE T2WI. One lesion appeared as isointensity and the other one was hypointensity on heavy T2WI with fat suppression technique because of containing most of fat. Vessels within the lesions appeared as curved linear or tubular hyperintensity resulting from slow blood flow also could be seen in four lesions. On dynamic contrast-enhanced arterial phase scanning, all of 12 lesions had enhancement. Central vessels could be shown within six lesions. On portal venous phase scanning, four lesions were hypointensity, the other eight lesions remained enhancement. The vessels within the lesions were still shown in seven lesions. Discussion and conclusion: MRI SE sequence with fat suppression technique combined with dynamic contrast-enhanced scanning could demonstrate the features of hepatic AML, such as fat components, marked inhomogeneous early and prolonged enhancement, especially the central vessels within the lesions suggested strongly the diagnosis of AML. MRI is helpful to improve the diagnostic accuracy. For atypical cases, it should be carefully differentiated from other hypervascular lesions like HCC, FNH, HCA and hemangioma.