Peritumoral spared area in fatty liver: correlation between opposed-phase gradient-echo MR imaging and CT arteriography

Background: The purpose of the present study was to evaluate the magnetic resonance findings of a spared area of fatty liver caused by hepatic tumors and clarify the etiology of this phenomenon by computed tomographic (CT) arteriography. Methods: Six patients with hepatic tumors (metastases from colon cancer, n = 3; breast cancer, n = 2; hepatocellular carcinoma, n = 1) were examined. In-phase (IP) and opposed-phase (OP) T1-weighted spoiled gradient-echo images were obtained. CT during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) were also performed. Pathologic confirmation was obtained in three patients with metastases from colon cancer. Results: In all six patients, peritumoral ringlike or wedge-shaped hyperintense areas in relation to the tumor and the surrounding steatotic liver parenchyma were clearly visualized on OP images alone. This area appeared as a perfusion defect on CTAP and ringlike or wedge-shaped enhancement on CTHA. Pathologically, the peritumoral hyperintense areas on OP images were compatible with the spared; area of fatty liver. Conclusion: A peritumoral spared area can be demonstrated with OP images. The etiology of the phenomenon is correlated with decreased portal flow and increased arterial flow in the peritumoral hepatic parenchyma.