CT灌注成像方法在评估脑转移瘤放射治疗疗效中的应用

Application of CT Perfusion Imaging in the Evaluation of the Effects of Brain Metastases with Radiation Therapy

目的研究CT灌注成像方法在脑转移瘤放射治疗疗效评价中的应用价值。方法对20例脑转移瘤病人全脑放射治疗前后分别行常规CT及CT灌注检查，得到TDC曲线，并合成脑血容量（CBV）图、脑血流量（CBF）图以及达峰时间（TTP）图。从灌注图像上测得感兴趣区的CBV、CBF以及TTP值并计算出相对CBV（rCBV）、相对CBF（rCBF）、相对TTP（（rTTP）。观察比较20例脑转移瘤患者瘤体实质以及正常脑实质放疗前及放疗后各项CT灌注参数的变化，并比较不同灌注参数的脑转移瘤的放疗疗效。结果放疗前的脑转移瘤瘤体实质区绝大部分均表现为rCBV、rCBF明显升高，rTTP略有降低。20例脑转移瘤放疗后2例体积无明显变化，其余18例均有不同程度的体积缩小。瘤体实质区的CBF、rCBF、rCBV均有明显降低，差异有统计学意义。rCBF低于3．0和rCBF高于3．0的脑转移瘤放疗后的治疗有效率及rCBF下降比率、rCBV下降比率差异有统计学意义。后者的放疗疗效明显高于前者。结论脑转移瘤的CT灌注图像具有一定的特征性表现；CT灌注成像方法能有效评价脑转移瘤的放疗疗效，并可在一定程度上对不同灌注参数的脑转移瘤进行放疗疗效的预测，rCBF高于3．0的脑转移瘤放疗后疗效比rCBF低于3．0的脑转移瘤放疗后疗效好。

Objective To investigate the value ofCT perfasion imaging in the evaluation of the effects of brain metastases with radiation therapy.Methods Both conventional and perfusion CT were performed in 20 patients with brain metastases before and after whole radiotherapy respectively.Then the TDC curves were obstained ,and cerebral blood flow （CBF） maps,cerebral blood volume （CBV） maps and time to peak （TTP） maps were generated. The CBF , CBV and TTP of the reagion of interest （ROI） were measured on the perfusion maps,and then the relative CBF（rCBF）,relative CBV（rCBV）,and relative TTP（rTTP） were calculated.The CT perfusion parameters of the parenchymatous tissue of brain metastases and the normal brain tissue before and after radiotherapy were compared.The effects of radiotherapy of the brain metastases with different perfusion parameters and with different pathologic sources were compared,too.Results The rCBF, rCBV of most brain metastases before radiation therapy were increased significantly.The rTTP decreased a little.The tumors of 2 cases had no significant change, but the tumors＇volume of other 18 cases decreased to a greater or lesser degree.The CBF, rCBF, rCBV of the parenchymatous tissue of tumors decreased significantly.The effects of the brain metastases with radiation therapy whose rCBF were higher than 3.0 were better than the ones whose rCBF were lower than 3.0.Conclusion Thebrain metastases before radiotherapy had characteristical behaves on the perfusion maps.CT perfusion imaging can evaluate the effects of brain metastases with radiotherapy efficiently. It can also predict the thearapeutic effects of metastatic brain tumors with various perfusion parameters in some ways.The thearapeutic effects of the brain metastases whose rCBF were higher than 3.0 were better than the ones whose rCBF were lower than 3.0.