Imaging diagnosis of hepatocellular carcinoma and premalignant/borderline lesions.

With the recent progress in imaging modalities, detection of small, nodular hepatic lesions has become much easier; however, differential diagnosis still remains difficult. Nevertheless, a combination of tomographic imaging techniques and angiography, such as ultrasound (US) angiography, CT arteriography (CTA), and CT during arterial portography (CTAP) has contributed considerably to the differentiation of overt (advanced) hepatocellular carcinoma (HCC) from benign or premalignant/borderline lesions. With such techniques, estimation of the grade of malignancy is also possible. Recently, noninvasive ultrasonographic vascular imaging techniques have been developed, such as color Doppler, power Doppler, and enhanced Doppler imaging. In particular, gray-scale contrast second harmonic imaging may prove useful in the management of HCC and will replace some of the roles of magnetic resonance imaging (MRI) and CT in the near future; ultrasonographic visualization of the vascularity of viable cancer cells is essential for the US-guided interventional therapy of HCC.