BOLD—fMRI在脑胶质瘤术后IMRT中视觉功能区保护价值

Value of BOLD-fMRI in the protection of visual function during postoperative intensity-modulated radiotherapy for cerebral gliomas

目的 评价血氧水平依赖功能MRI （BOLD-fMRI）在枕叶脑胶质瘤术后放疗视觉功能区保护中的临床应用价值。方法 选取2014—2016年间枕叶区脑胶质瘤术后拟行放疗病例28例。所有患者放疗前行定位CT、常规MRI及BOLD-fMRI检查,获得在3DT1解剖图像上显示的视皮质激活图,并以此为指导在定位CT图像上标记视皮质区,采用IMRT技术分别制定视觉功能区保护性放疗计划和未考虑视觉功能区的常规放疗计划。通过比较PTV的CI、HI、Dmax、Dmean以及视皮质区所受Dmax、Dmean,评价视觉功能区保护性方案的可行性。结果 常规放疗计划及视觉功能区保护性放疗计划在确保靶区有效治疗剂量及常规OAR剂量限制在安全可接受范围前提下,PTV的CI及HI差异无统计学意义（P=0.874、0.602）。视觉功能区保护性放疗计划患侧视皮质Dmax、Dmean分别降低8.40%、9.25%,健侧13.26%、14.77%。结论 利用BOLD-fMRI指导制定视觉功能区保护性放疗计划,在保证靶区处方剂量前提下,相比常规放疗计划,降低了视觉功能区受量,进而可以实现相应的功能区保护。

Objective To investigate the clinical value of blood oxygenation level-dependent functional magnetic resonance imaging （BOLD-fMRI） in the protection of visual function during postoperative radiotherapy for occipital lobe gliomas. Methods Twenty-eight patients with occipital lobe gliomas receiving postoperative radiotherapy from 2014 to 2016 were enrolled as subjects. All patients underwent computed tomography （CT） simulation, conventional MRI, and BOLD-fMRI before radiotherapy. The location and scope of the visual cortex on 3DT1 anatomical images were used to guide the labeling of the visual cortex on simulated CT images. A visual cortex protective radiotherapy plan and a conventional radiotherapy plan were made by intensity-modulated radiotherapy. The feasibility of the visual cortex protective radiotherapy plan was evaluated using conformity index （CI）, homogeneity index （HI）, Dmax, and Dmean for planning target volume （PTV） and Dmax and Dmean to the visual cortex. Results For the two plans, if the effective dose to target volume was guaranteed and the doses to conventional organs at risk were acceptable, there were no significant differences in CI or HI for PTV between them （P=0.874,P=0.602）.Compared with the conventional radiotherapy plan, the Dmax and Dmean to the ipsilateral visual cortex were reduced by 8.40% and 9.25%, respectively, while the Dmax and Dmean to the contralateral visual cortex were reduced by 13.26% and 14.77%, respectively, in the protective radiotherapy plan. Conclusions With a guaranteed prescribed dose to target volume and BOLD-fMRI used as a guide, the visual cortex protective radiotherapy, compared with the conventional plan, can reduce the dose to the visual cortex and protect the corresponding functional areas.