摘要
目的:探讨放射外科治疗的放射生物学效应。方法:报告4例放射外科治疗的手术病理改变,与影像改变及治疗计划等对照研究,结合文献复习,探讨放射生物机理。结果:4例出现不同程度变性、坏死、组织吸收及水肿反应,有剂量及时间依赖性。结论:放射外科治疗后病灶早期改变是血脑屏障紊乱和靶细胞超微结构改变,逐步出现水肿期、坏死期、吸收期及瘢痕期。在坏死期及吸收早期,从治疗体积中心向外依次为坏死区、变性与反应区、水肿区,分别与计算机体层摄影(CT)或磁共振成像(MRI)的中央无强化区、强化环、周围低密度或长T_1长T_2水肿样信号区相对应,水肿样改变主要与灶周剂量较高有关。坏死是靶细胞辐射损伤与血管闭塞相结合的结果,后者为管壁增厚和血栓形成所致。糖皮质激素对灶周水肿的疗效与血管壁损伤程度有关。
To investigate the radiobiological effects of the brain after radiosurgical treatment. Method: 4 cases in whom the operative brain specimens were obtained 4 ?7 months after radiosurgical treatment and the pathological changes of the tissues were observed. There were 2 cases of glioma, 1 case of AVM and 1 case of cavernous hemangioma. A comparative study was made of the imaging changes and treatment plans. The radiobiological mechanisms were discussed with a review of literatures. Result:There were varying degrees of degeneration, necrosis, tissue resorption and edema around the lesion, which were dose- and time-dependent. Conclusion: The early pathological changes after radio-surgical treatment include disruption of blood brain barrier (BBB) and ultrastructural damages of target cells. Then the lesions developed edema necrosis, resorption and finally glial scar formation resulted. At the necrotic stage,from the center to the perepheral there were the necrotic zone, degenerative and reactive zone and edema-tous zone, corresponding to the non-enhancement central area on CT or MRI, enhancing ring on CT or MRI and area with low-density on CT or low-signal on T_1WI and high-signal on T_2WI respectively. The edematous areas surrounding the lesions were caused predominantly by higher radiation doses. Tumor necrosis was the result of radiation damage combined with vascular occlusion. The latter was caused by thickening of blood vessel wall and thrombosis. The curative effects of glucocorticoid on the edema areas surrounding the lesions were related to the degree of vascular walls damage.
