Tumor Microvessel Density Is Associated With Tumor Perfusion Measured By Contrast-enhanced Ultrasound In Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent and mortiferous cancers, recognized as the third cause of cancer death worldwide, and the second in China.Hepatocellular carcinoma (HCC) is a typical hypervascular tumor; its growth and metastasis are dependent on angiogenesis. The microvessel density (MVD) of HCC represents the angiogenesis in the tumor and could be an independent factor in predicting the prognosis.Angiogenesis has become a particularly important feature for cancer biology and a target for tumor-directed therapy. There is still a problem, however, on how to evaluate the efficacy of anti-angiogenesis therapy. According to observations from published clinical studies, anti-angiogenesis therapy may not lead to substantial reduction in tumor volume; therefore, overall survival and progression-free survival rates are widely used to provide the efficacy evidence of anti-angiogenesis therapy. It is still difficult to provide biological evidence of anti-angiogenesis treatment, because patients' survival rates do not always directly reflect the biological characteristics of the tumor.The MVD of a tumor can represent the changes in tumor vasculature induced by anti-angiogenesis therapy in animal models. Therefore, a noninvasive or minimal invasive method to monitor changes in tumor vasculature, which could be observed repeatedly at a low cost, is urgently needed. Ultrasonography (US) is a rapid, relatively inexpensive technique that can be used easily in the laboratory and clinic. With the use of microbubble contrast agents, which are composed of microspheres and are highly reflective on US images even when very small doses are used, contrast-enhanced ultrasonography (CEUS) provides a more sensitive method to show tumor vasculature.Therefore, it remains to be answered whether CEUS can provide a quantitative measurement of tumor MVD, especially in HCC, which is usually embedded in the liver parenchyma. In this study, we analysis the relationship between the HCC microvessel density and the parameters of CEUS, and the relation may give us a mew method to evaluate the efficacy of anti-angiogenesis treatment of HCC. MethodsCEUS using a microbubble contrast agent was performed in 27 patients before hepatectomy for HCC. Time-intensity curves for regions of interest in tumors and adjacent tumor-free liver parenchyma located at the same depth were obtained. Tumor perfusion parameters were calculated by the mathematical function I(t) = BI + a₁e^-a2^t(1+e^-a3^t-to)^-1; values for perfusion parameters detected from adjacent tumor-free liver parenchyma were then subtracted from the tumor values. Tumor microvessels were visualized by immunohistochemistry with CD34 antibody, and MVD was calculated by an image analysis system at the magnifications 50×and 100×.ResultsTumor and liver perfusion parameters, including arrival time (AT), time to peak (TTP), acceleration time (ACT), mean transit time (MTT), baseline intensity (BI), peak intensity (PI), increase in signal intensity (ISI), rate of washout of 50% of contrast materials (a2), rate of increase in signal intensity to initial peak (a3), area under the curve (AUC), and blood flow coefficient (BF) were calculated. PI, ISI, AUC, and BF were standardized by subtracting the values obtained from adjacent liver parenchyma from the tumor values. MVD at 50x was 1.95±1.18% and correlated with PI (r=.49, P=.01), ISI (r = .51, P < .01), AUC (r = .65, P < .01), and BF (r = .68, P < .01). MVD at 50×magnification had a better association with tumor perfusion parameters compared with MVD at 100×magnification.ConclusionTumor perfusion parameters (PI, ISI, AUC, BF) are associated with tumor MVD, implying its significance in monitoring the effect of anti-angiogenesis therapy.The potential application of this workCEUS perfusion parameters have association with MVD in HCC which suggest that we have a new non-invasive method to evaluate the efficacy of anti-angiogenesis in vitro. The novelty of this workFor the first time, we suggested that there's non-invasive method which can apply the blood perfusion of hepatocellular carcinoma in vitro. And we suggest all these perfusion data with...