How to differentiate liver lesions in cirrhosis.

The diagnosis of hepatocellular carcinoma is based on imaging examinations in combination with clinical and laboratory findings. Despite technological advances, imaging cirrhotic patients remains a challenging issue, since preneoplastic hepatocellular lesions, such as dysplastic nodules, mimic a small hepatocellular carcinoma. 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 hepatocellular carcinoma in nodules larger than 1 cm showing arterial hypervascularization and venous wash-out. In lesions that do not show a typical pattern, biopsy is still recommended. Contrast-enhanced ultrasound, spiral computed tomography or dynamic magnetic resonance imaging are required for characterization of lesions in cirrhotic liver. However, during the development of hepatocellular carcinoma, significant histological changes are present with or without an evident arterial supply of the nodule. Due to the ability of magnetic resonance to investigate differences in soft tissues and to exploit the properties of tissue-specific contrast agents, this imaging modality is particularly useful in the demonstration of the pathologic changes that take place at the histological level and at the level of the biliary and reticuloendothelial systems during carcinogenetic process in liver cirrhosis.