Imaging blood flow characteristics of hepatocellular carcinoma.

Since a close relationship exists between intranodular hemodynamics and the grade of biological/pathological malignancy of a nodule occurring in the cirrhotic liver, an accurate evaluation of intranodular hemodynamics is highly essential. Intranodular hemodynamics in hepatocellular carcinoma (HCC) and borderline lesions can be evaluated correctly by invasive and noninvasive techniques. Invasive techniques such as ultrasound (US) angiography, computed tomographies during arteriography or arterial portography are sensitive in the detection of intranodular arterial and portal supplies, for accurate diagnosis of tumors and assessing grades of biologically malignant potential. However, these approaches require an angiographic procedure, which is not always available. Recently, perfusion imaging techniques under US, including contrast-enhanced harmonic imaging or real-time gray-scale harmonic imaging, have become available for routine clinical use. With these techniques, all the five roles of imaging in the management of HCC, i.e., detection, confirmation, staging, evaluation of malignancy grade, and postoperative follow-up, have become much simpler. Perfusion imaging techniques have reduced the requirement for dynamic CT or MRI and may replace some of their roles in the clinical setting. Since viable cancer cells are accurately imaged on US monitoring with sensitive perfusion imaging techniques, the contrast-enhanced harmonic imaging will be of great advantage in US-guided treatment of HCC. With the advent of rapid and remarkable advances in US harmonic imaging techniques, the diagnostic and therapeutic strategies for HCC are changing drastically.