MRI manifestations of liver epithelioid and nonepithelioid angiomyolipoma

Purpose: To retrospectively analyze the magnetic resonance imaging (MRI) manifestations of liver AML and compare the MRI manifestations of epithelioid and nonepithelioid angiomyolipoma (AML).

Materials and methods: The study comprised a retrospective analysis of 11 patients whose hepatic AML was confirmed by surgical pathology. Routine MRI examination was performed in 11 patients, of which five were cases of epithelioid AML and six were cases of nonepithelioid AML. One case of nonepithelioid AML underwent a plain MRI scan only, while the remaining 10 patients underwent MRI and dynamic contrast-enhanced scans.

Results: Chemical shift imaging detected more fat component cases than frequency the saturation method did (7/11 vs. 3/11). The difference was not statistically significant, however (P = 0.236). The degree of fatty component was different between epithelioid and nonepithelioid AML, but there was no significant difference between them (P = 0.766). Of the 10 cases in which enhancement scans were performed, nine had hyperenhancement in the arterial phase, and nine had capsule enhancement on delayed phase.

Conclusion: The amount of fat content is not related to whether the tumor is epithelioid or nonepithelioid. Under dynamic contrast-enhancement MRI, epithelioid AML shows enhancement patterns similar to those of classic AML rich in vascular smooth muscles.