RADIOLOGY: HEPATOBILIARY: Case# 62: HCC - 3 PHASE. This 50 year old white male with suspected liver mass. Pre-contrast, arterial phase, and venous phase images from a three phase CT show a large low attenuation mass involving almost all of the anterior segment of the right lobe of the liver and extending minimally into the medial segment of the left lobe of the liver. This shows minimal early peripheral enhancement. Additionally, streaky hazy changes are noted in the adjacent perihepatic fat. Two lesions in the left lobe are consistant with the simple cysts seen on the patients ultrasound. The portal veins are patent. The right hepatic artery originates off the superior mesenteric artery. There is no intrahepatic biliary ductal dilatation. The spleen, adrenal glands, kidneys, and pancreas appear unremarkable. Although uncommon in the United States, hepatocellular carcinoma is an important cause of death in parts of Africa and Asia because of the hepatotrophic viruses. In the United States, eighty percent of hepatocellular carcinomas arise in cirrhotic livers. Three patterns of tumor growth are seen: 50% present as a solitary tumor, 30% as a diffuse infiltrative tumor, and 20% as a multinodular tumor. The tumor usually appears as a hypodense or isodense lesion on nonenhanced images and enhances prominently during the arterial phase on dynamic contrast injection. Areas of tumor necrosis and calcification are common. Tumor invasion of hepatic and portal veins occurs frequently.