From the Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan (M.K., J.S., T.F., H.M., O.A.); and Department of Radiology, School of Medicine, International University of Health and Welfare, Chiba, Japan (M.A.).
Radiographics. 2021 Jan-Feb;41(1):224-248. doi: 10.1148/rg.2021200064. Epub 2020 Nov 20.
Radiation therapy (RT) continues to play a central role as an effective therapeutic modality for a variety of tumors and vascular malformations in the central nervous system. Although the planning and delivery techniques of RT have evolved substantially during the past few decades, the structures surrounding the target lesion are inevitably exposed to radiation. A wide variety of radiation-induced changes may be observed at posttreatment imaging, which may be confusing when interpreting images. Histopathologically, radiation can have deleterious effects on the vascular endothelial cells as well as on neuroglial cells and their precursors. In addition, radiation induces oxidative stress and inflammation, leading to a cycle of further cellular toxic effects and tissue damage. On the basis of the time of expression, radiation-induced injury can be divided into three phases: acute, early delayed, and late delayed. Acute and early delayed injuries are usually transient and reversible, whereas late delayed injuries are generally irreversible. The authors provide a comprehensive review of the timeline and expected imaging appearances after RT, including the characteristic imaging features after RT with concomitant chemotherapy. Specific topics discussed are imaging features that help distinguish expected posttreatment changes from recurrent disease, followed by a discussion on the role of advanced imaging techniques. Knowledge of the RT plan, the amount of normal structures included, the location of the target lesion, and the amount of time elapsed since RT is highly important at follow-up imaging, and the reporting radiologist should be able to recognize the characteristic imaging features after RT and differentiate these findings from tumor recurrence. RSNA, 2020.
放射治疗（RT）继续作为治疗中枢神经系统各种肿瘤和血管畸形的有效治疗方法发挥核心作用。尽管 RT 的规划和交付技术在过去几十年中发生了重大变化，但目标病变周围的结构不可避免地会受到辐射。在治疗后成像中可能会观察到各种各样的辐射诱导变化，这在解释图像时可能会令人困惑。组织病理学上，辐射会对血管内皮细胞以及神经胶质细胞及其前体细胞产生有害影响。此外，辐射会引起氧化应激和炎症，导致进一步的细胞毒性作用和组织损伤循环。根据表达时间，辐射诱导的损伤可分为三个阶段：急性、早期延迟和晚期延迟。急性和早期延迟损伤通常是短暂和可逆的，而晚期延迟损伤通常是不可逆的。作者全面回顾了 RT 后的时间线和预期的成像表现，包括伴随化疗的 RT 的特征性成像表现。讨论的具体主题包括有助于区分预期治疗后变化与复发性疾病的成像特征，然后讨论先进成像技术的作用。在随访成像中，了解 RT 计划、包含的正常结构数量、目标病变的位置以及 RT 后经过的时间长短非常重要，报告放射科医生应该能够识别 RT 后的特征性成像表现，并将这些发现与肿瘤复发区分开来。RSNA，2020 年。
