CT in hepatic cirrhosis and chronic hepatitis.

Cirrhosis is a diffuse liver disease with premalignant potential in which hepatocellular carcinoma (HCC) frequently develops. The hemodynamics of contrast material are the key to diagnosis of focal liver lesions with computed tomography (CT). Lesions with arterial-dominant vascularity, such as HCC, show brisk enhancement during the arterial phase, whereas lesions with portal blood supply can appear as hyperenhancing lesions in the portal phase. The advent of helical CT has significantly improved the CT examination of the liver because the arterial phase can be displayed independently of the portal phase. The addition of arterial phase imaging to conventional portal phase imaging seems to improve tumor detection and characterization. Although HCC is the single most frequent tumor seen in chronic liver disease, other lesions such as peripheral cholangiocarcinoma and hemangioma should be considered in the differential diagnosis. Optimization of helical CT techniques may allow better detection and characterization of these lesions. In addition to tumor detection, CT plays an important role in preoperative staging of HCC as well as in preoperative assessment of patient candidates to hepatic transplantation. The use of CT angiography with maximum intensity projection techniques may allow for better preoperative work-up and vascular mapping in HCC patients. This article shows the spectrum of helical CT findings in chronic liver disease and specifically in the imaging of HCC and other focal lesions.