Baseline imaging of hepatocellular carcinomas

Current baseline imaging of hepatocellular carcinomas (HCCs) starts with transabdominal ultrasound (US), amplified by color Doppler and echo contrast agents if available. Multislice computed tomography (multislice CT) and magnetic resonance imaging (MRI) are further steps in the detection and possible characterization of HCC. However, there are no definite criteria that allow a firm differential diagnosis. Detection becomes even more difficult in the cirrhotic liver since regenerative nodules may mimic tumors. In these cases echo-contrast-enhanced US or MRI using liver-specific contrast agents offer clarification. Further developments are to be expected in this field. Negative or nondiagnostic serum alpha-fetoprotein (AFP) levels (<400-500 ng/ml) require fine-needle biopsy under sonographic control in most cases. Locoregional therapy modalities such as percutaneous ethanol injection, radiofrequency thermoablation, laser-induced thermotherapy and transarterial chemoembolization are monitored by either US or CT or MRI. Tumor response is evaluated in terms of size reduction, decrease of vascularization or the detection of possible metastases. Tumor vascularization could be verified by contrast agents for which, especially with respect to echo contrast agents and liver-specific contrast agents, further developments are to be expected. Postinterventional imaging is required to monitor possible complications such as liver infarction, liver necrosis, cholangitis, cholecystitis, or vascular thrombosis.