Noninvasive diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the 6th most common cancer in the world and the third most common malignant tumor following stomach and lung cancers in Korea. Approximately 90% of HCCs are associated with a known underlying risk factor. The most frequent risk factors include chronic viral hepatitis (hepatitis B virus, hepatitis C virus) and alcohol intake. Cirrhosis is an important risk factor for HCC, and may be caused by chronic viral hepatitis, alcohol, non-alcoholic fatty liver disease and inherited metabolic diseases. Tests that can be used in HCC surveillance include serological and imaging examinations. The imaging test most widely used for HCC surveillance is ultrasound (US). US has an acceptable diagnostic accuracy when used as a HCC surveillance test (sensitivity, 58-89%; specificity, >90%). Alpha-fetoprotein (AFP) is the most widely tested biomarker in HCC. However, analysis of recent studies showed that AFP determination lacks adequate sensitivity and specificity for effective surveillance and for diagnosis of HCC. Accurate diagnosis of small liver nodules is of paramount importance. Diagnosis of HCC is based on noninvasive criteria or pathology. The noninvasive diagnostic criteria are relevant for the management of patients with suspicion of HCC when small nodule is found in liver. In 2001, a panel of experts on HCC reported for the first time noninvasive diagnostic criteria for HCC based on a combination of imaging and laboratory findings. In 2005, the European Association for the Study of the Liver (EASL) panel of experts and the American Association for the Study of Liver Diseases (AASLD) guidelines adopted a new HCC radiological hallmark, i.e. hypervascularization on arterial phase imaging and washout in the portal or delayed phase. In the presence of cirrhosis, noninvasive diagnosis of HCC can be obtained by one dynamic imaging technique in nodules above 2 cm showing the HCC radiological hallmark and two coincidental dynamic imaging techniques with nodules of 1-2 cm in diameter. Dynamic imaging techniques include contrast-enhanced ultrasound (CEUS), computed tomography (CT), and magnetic resonance imaging (MRI). Recent updated guidelines have proposed that one dynamic imaging technique (contrast-enhanced CT or MRI) showing the HCC radiological hallmark suffices for diagnosing nodules of 1-2 cm in diameter. When the typical vascular patterns are not present, either other contrast-enhanced study or biopsy is recommended. CEUS may offer false positive HCC diagnosis in patients with intrahepatic cholangiocarcinoma. Thus, CEUS has been dropped Noninvasive diagnosis of hepatocellular carcinoma