Hepatoeellular carcinoma(HCC)is a relatively commonmalignant tumor in Japan．According to data from the Liver Cancer StudyGroup of Japan(LCSGJ)，almost 17，000 patients withHCCwere newly registered in two years，2002 and 2003.Because more 80％of patients with HCC in Japanare infected with the hepatitis C(HCV)or hepatitis Bvirus(HBV)，their liver function is often poor and theysometimes have synchronous or metaehronous multi-centric occurrence of the tumor．Therefore，diagnostic imaging(CT，MRI，PET，Angiography，and Uhrasonography(US))is mandatory to detect the size，location，and numberof the primary tumor，to identify whether there isencapsulation，vascular invasion，lymph node or distantmetastasis，and to complete the staging of HCC．