Assessment of Angiogenesis of Hepatic VX2 Carcinoma: Usefulness of Perfusion CT

ABSTRACT

PURPOSE: To investigate the perfusion characteristics of VX2 carcinoma and liver parenchyma in an animal model, and to evaluate the usefulness of perfusion CT in assessing the angiogenesis of hepatic VX2 carcinoma. MATERIALS AND METHODS: Ten rabbits (control, 5; VX2 carcinoma, 5) weighing 2.5 to 3.5 (average, 3.1) Kg were involved in this study. Between 7 and 14 days after implanting VX2 carcinoma, ultrasonography and CT were performed for the purpose of detecting this. Using the cine mode and involving four simultaneous sections, four perfusion CT images were obtained every second for 60 seconds. One radiologist measured the size of the region of interest (ROI) at each liver location, and using the time-density curves for each tumor and normal liver, semi-quantitative perfusion parameters -namely blood volume, mean transit time (MTT), blood flow, and time-to-peak enhancement-were determined. The microvascular densities (MVD) of VX2 tumors and normal liver were correlated with the perfusion CT findings. RESULTS: In the control group, there were no significant differences in perfusion parameters between the left and right hepatic lobes. In the VX2 carcinoma group, there were significant differences between the lobe containing the tumor and adjacent hepatic lobes with respect to blood volume (34.80 vs. 27.2 ml/100 g), MTT (14.1 vs. 19.4 sec), blood flow (119.7 vs. 84.3 ml/100 g/min), and time-to-peak (32.4 vs. 36.9 sec) (p<0.05). The blood volume (27.2 ml/100g) of the hepatic lobe with the VX2 tumor was higher than that of normal liver (22.8 ml/100 g) (p< 0.05), but blood flow (84.3 vs. 66.8 ml/100 g/min), MTT (19.4 vs. 21.3 sec) and time-to-peak (36.9 vs. 38.7 sec) values were not different. The MVD of VX2 tumors was higher than that of normal liver (p<0.05), and significantly higher than that of adjacent and contralateral liver (p<0.05). CONCLUSION: At perfusion CT, blood volume and blood flow of VX2 carcinomas increased more than those of normal liver, as were both mean transit time and time-to-peak. It was confirmed histopathologically that the angiogenesis of VX2 carcinoma was higher than that of normal liver. In conclusion, perfusion CT may be a practically useful diagnostic tool capable of reflecting the neoplastic angiogenesis of the liver.