Portal architecture: a differential guide to fatty infiltration of the liver on computed tomography.

Fatty infiltration of the liver, like fatty lesions elsewhere in the body, typically appears as low-density areas on computed tomography (CT). Fatty infiltration of the liver should be considered in the differential diagnosis of homogeneous low-density hepatic lesions regardless of distribution or size. As a physiologic rather than anatomic change, fatty infiltration of the liver characteristically leaves the portal venous architecture unaltered. Although fatty infiltration of the liver typically presents with complete or near complete involvement, other unusual patterns may be encountered. In these atypical cases, recognition of the normal portal structures on CT aids in correct diagnosis.