扩散张量成像在脑胶质瘤术后调强放疗中的临床应用初探*

目的:探讨扩散张量成像（diffusion tensor imaging，DTI）在指导邻近皮质脊髓束（corticospinal tract，CST）脑胶质瘤术后放疗方案中的应用价值。方法:30例邻近CST 脑胶质瘤术后拟行放疗患者，行常规MRI 平扫+ 增强及DTI 检查。获取CST 相关数据并与相应的MR、CT解剖图像融合，导入放疗计划系统并依此勾画靶区、危及器官及CST ，采用调强放疗（IMRT）技术分别制定考虑和不考虑CST 剂量保护的两种放疗计划并进行比较。结果:在两种计划均达到靶区治疗剂量及常规危及器官保护的情况下，考虑CST 剂量保护的放疗计划中的患者患侧、健侧CST 所受最大辐射剂量和平均辐射剂量均低于不考虑CST 剂量保护的放疗计划（P<0.05）。 结论:DTI 能够明确CST 的位置、形态及与脑胶质瘤术后放疗靶区的关系，有助于制定保护性放疗方案，最大程度减低CST 所受辐射剂量，从而降低放疗后发生神经损伤的可能。 

Clinical application of diffusion tensor imaging in postoperative in-tensity modulated radiotherapy for gliomas

Objective:To evaluate the application value of diffusion tensor imaging (DTI) in guiding the postoperative radiothera -py plan of the gliomas adjacent to the corticospinal tract (CST). Methods:Thirty patients with gliomas adjacent to the CST underwent routine magnetic resonance imaging (MRI) contrast-enhanced scanning and DTI after radiotherapy. Tractography data sets were ac -quired and were fused with the images of corresponding anatomical MRI and computed tomography. The acquired data sets of radio-therapy planning system were imported to assist with the delineation of the target volume, organs at risk, and CST. Two sets of radio -therapy plan, which considered or did not consider the dose protective effect of the CST, were formulated and compared using the treat -ment technique of intensity modulated radiotherapy. Results:The protective radiotherapy and unprotected plans both achieved the thera -peutic dose to the target volume and the protection of the routine organs at risk. In the protective dose (with an optimization program that considered the dose reduction of CST), the maximum and mean radiation doses suffered by the patients' ipsilateral and contra-later -al CSTs were lower compared with the unprotected plan ( P<0.05). Conclusion : DTI can identify the location and shape of CSTs, and their relationship with the postoperative radiotherapy target of gliomas. These findings contribute to the formulation of a protective ra -diotherapeutic regimen to keep the CST from the maximum and the mean radiation doses to the largest extent, thereby decreasing the possibility of nerve damage after radiotherapy.