Doppler and harmonic ultrasound for hepatocellular carcinoma.

Ultrasound (US) is the imaging method most frequently used for the detection and diagnosis of hepatocellular carcinoma (HCC). US image quality has greatly improved in recent years, with advances in transducer, beam-former technology and sophisticated image processing. In addition, the recent availability of US contrast agents including first- and second-generation contrast agents and the remarkable advances in US technology have led to the rapid development of new imaging methods such as low and high mechanical index (MI) imaging technology for the vascular phase and parenchymal phase of the liver. In terms of contrast agent, most reported studies in Asian countries have used a very fragile, first-generation microbubble agent. Nowadays, more stable,second-generation contrast agents are developing and used in clinical application to the liver. In the future, better results can be obtained in the diagnosis of HCC, decision of treatment method and assessment of therapeutic response if more durable contrast agents are used with advanced US techniques. In this article, the principles, methods, imaging findings and potential roles of new diagnostic US techniques with contrast agents in the diagnosis of HCC are discussed.