Lo E H, Frankel K A, Steinberg G K, DeLaPaz R L, Fabrikant J I
Department of Neurosurgery, Stanford University School of Medicine, CA.
Int J Radiat Oncol Biol Phys. 1992;22(1):47-55. doi: 10.1016/0360-3016(92)90981-m.
Radiation-induced alterations in cerebrovascular and metabolic function form the basis for the radiosurgical treatment of selected intracranial vascular malformations and tumors in human patients. However, the underlying mechanisms, temporal progression, and modifying factors involved in the radiosurgical obliteration of these intracranial lesions as well as the risks of delayed radiation injury to surrounding normal brain remain poorly understood. In this report, the rabbit brain was used as an animal model to examine the effects of high-dose single-fraction X-irradiation on magnetic resonance imaging (MRI) appearance, neurophysiologic function, and histological integrity. At approximately 10 weeks following left-hemisphere irradiation with 60 Gy (225 kVp) X rays, MRI studies showed radiation-induced changes including blood-brain barrier (BBB) perturbations in the white matter regions and the hippocampus. Significant reductions in regional cerebral blood flow (rCBF) ratios were found in the hippocampus and certain regions of the cortex in irradiated animals. However, no changes in somatosensory evoked potentials (SEP) were observed. Histological studies demonstrated telangiectatic vessels, spreading edema in the white matter, and focal regions of necrosis and hemorrhage in the irradiated cortices and hippocampi. These results demonstrate that the irradiated rabbit brain may be used as an experimental model to correlate the spatiotemporal pattern of functional changes with radiologic and histological changes in delayed radiation injury.
辐射引起的脑血管和代谢功能改变构成了人类患者中对选定的颅内血管畸形和肿瘤进行放射外科治疗的基础。然而，这些颅内病变放射外科闭塞所涉及的潜在机制、时间进展和调节因素，以及对周围正常脑组织延迟性辐射损伤的风险，仍知之甚少。在本报告中，兔脑被用作动物模型，以研究高剂量单次分割X射线照射对磁共振成像（MRI）表现、神经生理功能和组织学完整性的影响。在用60 Gy（225 kVp）X射线照射左半球后约10周，MRI研究显示出辐射诱导的变化，包括白质区域和海马体中的血脑屏障（BBB）紊乱。在受照射动物的海马体和某些皮质区域发现局部脑血流量（rCBF）比率显著降低。然而，体感诱发电位（SEP）未观察到变化。组织学研究显示，照射后的皮质和海马体中有扩张的血管、白质中的弥漫性水肿以及坏死和出血的局灶区域。这些结果表明，受照射的兔脑可用作实验模型，以将功能变化的时空模式与延迟性辐射损伤中的放射学和组织学变化相关联。
