A Study Of Dual Source CT In Evaluating The Angiogenesis Of Hepatic Carcinoma After Treatment With Sorafenib

Background and ObjectiveThe incidence of primary hepatic carcinoma is one of the highest among the malignant tumors. The mortality of primary hepatic carcinoma is located in the second place, just behind lung tumor in China. Thus, many researchers have been focused on the study of biological behavior, diagnosis and treatment of it. Rabbit VX2liver cancer model is similar as human liver cancer in shape, biochemistry and biology behavior, and it possesses the feature of transplantable, rapid-growth and powerful invasion. Therefore, rabbit VX2liver cancer model is suitable to carry on imaging research of hepatic carcinoma. The ideal liver cancer model should be high-repeatability, simple method and tiny injured to animals except for high rate of tumor formation. This research improved the method of modeling rabbit VX2liver tumor in some aspects to approach a steadier, easier, tinier injured way to spread the application.In the pathology process of genesis, development, invasion and metastasis in hepatic carcinoma, angiogenesis possesses special important place. However, the forthcoming imaging observation means on liver cancer angiogenesis cannot satisfy us in liver cancer experimental and clinical research. We try to exploit a new examination technique of dual-energy scanning mode of DECT. In this way, we can carry on real-time and precise observation in the growth and treatment procedure of liver cancer, and this has already become the central issue to improve the effect of diagnosis, treatment and prognosis evaluation in liver cancer.In recent years, molecular targeted drugs arouse much attention gradually. The representative drug Sorafenib has shown fine therapeutic effect on liver cancer. Sorafenib inhibits intracellular Raf kinase by targeting on Ras/Raf/MEK/ERK signal transduction path to decrease the proliferation of tumor cell, as well as the tyrosine kinase activities of VEGFR, PDGFR, Flt-3and c-Kit to reduce angiodenesis.This research performed DSCT perfusion and DE mode in rabbit VX2liver tumor model by applying Sorafenib to detect tumor angiogenesis condition. The objective of the research is as follows:①To assess the diagnostic value of VX2hepatic tumors by DSCT perfusion and DE mode;②To observe the features of blood supply situation in the process of targeted drug therapy by the two imaging techniques;③Combined with pathology, VEGF and MVD staining results, analysis the correlation between the display of blood supply vessels and DSCT perfusion parameters, iodine concentration difference.Materials and methodsSixty male New Zealand white rabbits, weighing3.5±0.4kg, were allocated randomly. The VX2liver cancer mass were implanted into the liver of rabbit via reforming laparotomic route.Fifteen cancer models were allocated randomly to observe the size, shape, CT contrast enhancement scanning and pathologic changing at the7th,14th,21st days after the reforming surgery.Forty models of regular shape, diameter>1cm and basically equal size were chose through CT contrast enhancement scanning at the7th day after surgery. The models were divided into two groups randomly. Group A was the control group:PO glucose; Group B was the experiment group:PO Sorfenib.The rabbits were performed by DSCT perfusion and dual-energy scan at the7th,14th (7days after treatment),21st (14days after treatment) days. Compared the DSCT perfusion parameters in tumor areas:Blood Flow (BF), Blood Volume (BV), RSquare [RSQ(P)], Art. Liver Perfusion (ALP), Port V. Liver Perfusion (PVP), Hepatic Perfusion Index (HPI), normalized iodine concentrations (NIC) and lesion-to-normal parenchyma ratio (LNR) with or without Sorfenib.Six models were chosen randomly at each CT scanning time. After executed these rabbits, the growth information of the tumors were observed and liver specimen were made into paraffin block to perform H-E staining, MVD and VEGF immunohistochemistry examination, and detect the expression of VEGF protein by using Western Blot.The correlations between DSCT perfusion parameters and iodine concentration difference results and MVD values of VX2liver tumor models at each scan time were measured.SPSS13.0software package applied for statistical analysis. Significant level was set as a=0.05.Results1. The effects of reforming implantation and the imaging and pathology features:Operation time and bleeding condition:the average bleeding volume was less than0.3ml; the average operation time was16.20±1.92min. None animal was dead in observation time (21days).DSCT contrast enhancement scanning:Low density in the left lobe under appendix ensiformis of DSCT plain scan was found at the7th day after surgery. It showed significantly ring-enhancement in arterial phase and decreased in venous phase. The internal was uniformity and lightly enhanced. Pathology results verified the liver cancer growth, and implantation success rate was100%. As the14th and21st days scanning, we found the implanted tumors were regular in shape (round or oval), larger in size, rapidly increased insize and low density necrosis in center at the third week.Pathology observation:The specimens of liver cancer were solid and gray fish-like nodule, unclear border and gray-yellow liquation area in tumor center. HE staining showed VX2tumor cells were diffuse or nest-like scattered. The HE staining showed obviously atypia, fusiform shape or irregular shape of cancer cells. MVD staining showed much regeneration vessels in the cancer nests.2.The DSCT perfusion, iodine concentration difference and pathological features of VX2tumor models after treatment:The tumor size(diameter) between the two groups:group A were1.02±0.21cm,1.73±0.35cm and2.80±0.73cm at the7th,14th and21st days respectively; group B were1.02±0.31cm,1.52±0.70cm and1.81±0.93cm at the7th,14th and21st days separately.DSCT perfusion and iodine concentration difference:There was significantly different in HBF, HBV, ALP, HPI values (P<0.05) between the two groups at each time. There was no significant difference of PVP and RSQ values. Statistic analyzing showed NIC and LNR changed evidently at the14th day after treatment, and there was significant difference (P<0.05).3.The correlation between DSCT perfusion parameters, iodine concentration difference results and MVD values and reliability of the evaluation methods:There were positive correlations between MVD counting and the data of CT perfusion BV, HPI and iodine concentration NIC and LNR in the rim of the tumor (r>0.9); and there were positive correlations between MVD counting and the data of CT perfusion ALP and HBF and no correlations between MVD counting and PVP and RSQ.Conclusions1. This research established a steadier and easier method by improving rabbit VX2hepatic carcinoma model. This method was high-repeatable, simple, tiny injured to animals, high rate of tumor formation and can be used widely in related experiments. Target therapy drugs showed evident effect on inhibiting angiogenesis and tumor growth in this model.2. Combining with pathologic results, DSCT perfusion and iodine concentration acquired by dual-energy scanning mode were reliable methods to evaluate the tumor blood supply. What’s more, dual-energy scanning mode was much lower in radiation dose and was worth spreading as a new kind of imaging technique.