Detection of tumor parenchymal blood flow in hepatic tumors: value of second harmonic imaging with a galactose-based contrast agent.

Purpose. To evaluate the detectability of tumor vascularity in hepatic tumors by second harmonic imaging with the administration of a microbubble contrast agent, Levovist. Materials and methods: Twenty-four patients with hepatic tumors (21 hepatocellular carcinoma, one focal nodular hyperplasia and two liver metastasis) were studied using Aloka SSD 5500 with the administration of Levovist. Intermittent harmonic gray-scale imaging (HGSI) and intermittent harmonic power Doppler imaging (HPDI) were performed on every tumor and the detectability of the two harmonic imaging modes were compared with that of dynamic CT. Results: Tumor vessels and tumor parenchymal blood flow were obtained in hypervascular tumors in the early arterial phase, and metastasis presented peripheral enhancement. When dynamic CT was taken as a gold standard, the sensitivity, specificity and accuracy of detecting tumor vascularity for intermittent HGSI were 55.6, 100 and 66.7%, and for intermittent HPDI were 83.3, 100 and 87.5%, respectively. The difference of detectability between the two modes was statistically significant (P<0.05). Depth of the lesion from the abdominal wall was a major factor affecting the detectability of tumor vascularity. Conclusion: With the administration of Levovist, intermittent HPDI was more sensitive than intermittent HGSI to demonstrate tumor vessels and tumor blood flow. Second harmonic imaging with Levovist would be a promising valuable means for investigating specific vascular features in hepatic tumors.