Higashi H, Matsumoto K, Nakagawa M, Furuta T, Ohmoto T
Department of Neurological Surgery, Okayama University Medical School, Japan.
Neurol Med Chir (Tokyo). 1995 Sep;35(9):639-47. doi: 10.2176/nmc.35.639.
The effects of irradiation on a large volume of normal brain tissue as occurs in interstitial brachytherapy were investigated. Double iridium-192 seed assemblies were stereotactically implanted into the right centrum semiovale of eight adult Japanese monkeys (Macaca fuscata). The morphological changes induced in the normal brain tissue were evaluated with magnetic resonance (MR) imaging with and without gadolinium-diethylenetriaminepenta-acetic acid (Gd) enhancement at 2 days and 1, 3, and 6 months after the brachytherapy. After each MR imaging examination, randomly selected experimental animals were sacrificed to analyze the histological changes. The low intensity area seen inside the ring of contrast enhancement on the T1-weighted image with Gd enhancement was well correlated with histologically defined necrosis. The high intensity area seen outside the area showing contrast enhancement on the T2-weighted image was well correlated with an area of histological edema and demyelination. The sizes of the lesion and the high intensity area were maximum during the acute stage (2 days) following interstitial irradiation. This monkey model with MR imaging can be used to investigate the development of brain damage induced by interstitial irradiation. We further recommend careful monitoring to detect the development of brain edema during the acute stage after interstitial brachytherapy, especially when large tumors are treated.
研究了间质近距离放射治疗中对大量正常脑组织进行照射的影响。将双铱-192籽源组件立体定向植入八只成年日本猕猴（食蟹猴）的右侧半卵圆中心。在近距离放射治疗后2天、1个月、3个月和6个月，通过有无钆-二乙烯三胺五乙酸（Gd）增强的磁共振（MR）成像评估正常脑组织中诱导的形态学变化。每次MR成像检查后，随机选择实验动物处死以分析组织学变化。在Gd增强的T1加权图像上，对比增强环内所见的低强度区域与组织学定义的坏死密切相关。在T2加权图像上，对比增强区域外所见的高强度区域与组织学水肿和脱髓鞘区域密切相关。间质照射后的急性期（2天），病变和高强度区域的大小最大。这种具有MR成像的猕猴模型可用于研究间质照射引起的脑损伤的发展。我们进一步建议在间质近距离放射治疗后的急性期仔细监测以检测脑水肿的发展，尤其是在治疗大肿瘤时。
