Lobar attenuation difference of the liver on computed tomography.

Lobar attenuation difference of the liver was demonstrated by computed tomography (CT) in 16 cases among over 1,000 cases in which CT scans of the liver were obtained. Cases were divided into two groups: with liver tumor and without liver tumor. Among the former group, hepatocellular carcinomas is the predominant lesion; tumor thrombus in the portal vein is presumably the cause of the attenuation difference. The latter group includes the patients with hepatocellular disease and clinically normal patients. In the former group, the tumor itself could not be noted in precontrast scans in eight out of 12 cases. When lobar attenuation difference of the liver is noted, a postcontrast scan should be obtained to determined whether there is a liver tumor in the lobe of lower attenuation.