基于多模态MRI技术构建脑胶质瘤个体化放疗生物靶区的研究

Glioma is the most common and fatal primary tumor in the central nervous system. To kill or control neoplastic cells, postoperative adjuvant radiation therapy is widely accepted as an effective therapy for glioma. CT and magnetic resonance imaging (MRI) are traditionally used for treatment planning of glioma. However, as demonstrated the high recurrence rate in clinical practice, the identification of target volume by using the conventional imaging for radiotherapy of glioma is still an unsolved problem. Recent and current developments in radiotherapy such as intensity-modulated and adaptive techniques would greatly benefit from additional functional information allowing for definition of the biological target volume. Besides mere volumetric visualization of morphology and structure, MRI is also capable of providing 'functional' information which can be used to define individual biological target volumes. Unlike conventional MRI, which provides structural information based on signals from water, proton magnetic resonance spectroscopy (1H-MRS) provides spatially encoded chemical information, thus providing a noninvasive biochemical assay of tissue in selected regions of brain, including choline (Cho), creatine (Cr) and N-acetylaspartate (NAA). Some studies have shown that changes in metabolite levels may help to differentiate normal from abnormal tissue in patients with glioma. Our resent studies showed that gliomas revealed increases in the Cho/Cr and Cho/NAA ratios. We also noted 1H-MRS could enable noninvasive evaluation of cerebral glioma grade and distinction of recurrent glioma from radiation injury based on biochemical difference between regions of enhancing area. Thus, this technique may be an emerging powerful tool for evaluation of invasiveness and radiosensitivity in cerebral glioma. Definition of organs at risk is a crucial task for radiation oncologists when aiming to optimize the benefit of radiation therapy. Diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) investigate two complementary aspects of brain networks: white matter anatomical connectivity and gray matter function. The displacement of important neural structures, e.g. the pyramidal tract, by a large glioma can be exactly localized by using DTI and fMRI, and taken into account when the planned target volume is defined. DTI and fMRI appear helpful in the delineation of organs at risk. The project takes the glioma cell line, animal models and patients as the investigative object. Based on our previous study on glioma, we make efforts to 1) reveal the invasiveness and radiosensitivity of glioma by using 1H-MRS, 2) reveal tissue at risk by integration of DTI and fMRI, and 3) probe the feasibility and effectiveness of the delineation of biological target volume for radiotherapy by using non-invasive multimodal MRI technology. This will be probe out a novel and practicable method in clinic for patients with glioma treated by radiotherapy.

脑胶质瘤是中枢神经系统中最常见的原发性肿瘤，一旦发病将严重影响患者的生活质量，甚至危及患者的生命。放射治疗是治疗脑胶质瘤广泛采用的有效方法，它可以杀灭或抑制肿瘤细胞，延长患者的生存期。然而，目前常规影像学指导下的脑胶质瘤放射治疗有其局限性，而且不能用于指导脑胶质瘤生物靶区的勾画，因此不能实现不同生物靶区给予不同剂量的照射并最大限度地保护敏感组织。为了实现脑胶质瘤放射治疗生物靶区的构建，本项目拟采用无创性多模态MRI技术（包括常规MRI、磁共振波谱成像、磁共振张量成像及功能磁共振成像），在前期对脑胶质瘤研究的基础上，以脑胶质瘤细胞株、脑胶质瘤动物模型和脑胶质瘤患者为研究对象，研究脑胶质瘤的侵袭性、放射敏感性和危及器官，探讨基于多模态MRI技术构建脑胶质瘤放射治疗生物靶区的可行性及有效性，这不但为实施脑胶质瘤个体化放射治疗提供理论依据，也为脑胶质瘤放射治疗探索出一种新的临床切实可行的方法。

脑胶质瘤是中枢神经系统中最常见的原发性肿瘤，一旦发病将严重影响患者的生活质量，甚至危及患者的生命。放射治疗是治疗脑胶质瘤广泛采用的有效方法，它可以杀灭或抑制肿瘤细胞，延长患者的生存期。然而，目前常规影像学指导下的脑胶质瘤放射治疗有其局限性，而且不能用于指导脑胶质瘤生物靶区的勾画，因此不能实现不同生物靶区给予不同剂量的照射并最大限度地保护敏感组织。为了实现脑胶质瘤放射治疗生物靶区的构建，本项目采用无创性多模态MRI技术（包括常规MRI、磁共振波谱成像、磁共振张量成像），在前期对脑胶质瘤研究的基础上，以脑胶质瘤细胞株、脑胶质瘤动物模型和脑胶质瘤患者为研究对象，研究脑胶质瘤的侵袭性、放射敏感性和危及器官，探讨了基于多模态MRI技术构建脑胶质瘤放射治疗生物靶区的可行性及有效性。结果显示磁共振波谱成像可用于评价胶质瘤细胞放射敏感性及肿瘤细胞浸润，弥散张量成像可清晰显示脑白质区纤维束走形，联合磁共振波谱成像及弥散张量成像可在保护危及器官的同时精确确定放疗靶区。这为实施脑胶质瘤个体化放射治疗提供理论依据，也为脑胶质瘤放射治疗探索出一种新的临床切实可行的方法。