Imaging diagnosis.

The diagnosis of hepatocellular carcinoma (HCC) is based on imaging examinations in combination with clinical and laboratory findings. Despite technological advances, imaging cirrhotic patients remains a challenging issue because nonmalignant hepatocellular lesions, such as dysplastic nodules, mimic a small HCC. One of the key pathologic factors for differential diagnosis that is reflected in imaging appearances is the vascular supply to the lesion. It is accepted that imaging techniques may establish the diagnosis of HCC in nodules larger than 2 cm showing characteristic arterial hypervascularization. In lesions ranging from 1 to 2 cm, biopsy is still recommended, although a negative response can never be used to rule out malignancy completely. Although ultrasonography is widely accepted for HCC surveillance, spiral computed tomography (CT) or dynamic magnetic resonance imaging is required for diagnostic confirmation and intrahepatic tumor staging. These examinations have replaced invasive procedures, such as lipiodol CT, but remain relatively insensitive for the detection of tiny HCC lesions and tumor vascular invasion into peripheral portal vein branches.