MR灌注加权成像对兔肝VX2种植瘤三维适形放疗前后的比较研究

The Control Study in Rabbit Models of Hepatic VX2 tumors by perfusion-weighted imaging with before and after three-dimeusional conformal radiotherapy

目的通过对兔肝VX2种植瘤行三维适形放疗前、后MR成像特点及灌注参数变化的相关研究，为MR灌注加权成像作为肝癌疗效评估这一较新的影像学手段提供实验依据。方法新西兰大白兔肝VX2模型，分为放疗组和对照组，放疗前、后行MR扫描。选取病灶与瘤周肝组织感兴趣区（ROI），测量血流灌注值，进行统计学分析。PWI采用信号强度-时间曲线的最大信号下降斜率（SRSmax）作为定量指标，分析不同ROI的SRSmax下降程度及规律。结果治疗组放疗后肿瘤中央区及瘤周区SRSmax值均较放疗前降低（P〈0．05），有统计学差异。结论PWI能反映VX2种植瘤放疗后微循环及血流动力学变化，SRSmax可作为一种活体评价肿瘤微血管的指标。

Objective With comparative study of MR perfusion-weighted imaging characteristics and parameters change both before and after three-dimensional conformal radiotherapy, supposed to provide experimental basis for evaluation of PWI in measurement of effect on rabbit models of hepatic VX2 tumors. Methods New Zealand rabbits, were implanted in liver with VX2 tumor by tissue block, were divided randomly into radiotherapy and control group, PWI were performed both before and after the radiotherapy for the two groups. Select the ROI of the VX2 tumor center, tumor border and paratumor parenchyma. Maximal signal reduction slope （SRSmax） of the signal intensity versus time curves were created as quantitative variable. Analysis the laws of SRSmax decline levels of different ROI. Results The SRSmax of tumor center and tumor border of treatment group by 3DCRT were lower than before radiotherapy（ P 〈 0. 05 ） ;there were statistical significance. Conclusion PWI reflects the microcirculatian and hemodynamic changes of rabbit models of hepatic VX2 tumors by 3DCRT. SRSmax can be used as a live evaluation of tumor microvascular indicators.