CT and MR imaging of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the fifth most common tumor in the world and the incidence is expected to increase in the future due to hepatitis viral infections and increasing cirrhosis incidence. The diagnosis of HCC is no longer based on biopsy especially in cases when curative treatment is possible. The imaging criteria are usually based on the vascular findings of HCC (e.g. early arterial uptake followed by washout in the portovenous and equilibrium phase). However, there are several limitations of the assessment of HCC by using only the vascular criteria. The use of tissue-specific contrast agents, including superparamagnetic iron oxides and hepatobiliary contrast agents, improves lesion detection and characterization. Therefore, an accurate diagnosis of HCC implies, at this moment, a combination of vascular and cellular information. This review focuses on the most important findings provided by the unenhanced and dynamic-enhanced CT and MR images regarding HCC evaluation. We also discuss the various imaging characteristics of HCC at MR imaging after the administration of tissue specific contrast agents.