Kennedy A S, Archambeau J O, Archambeau M H, Holshouser B, Thompson J, Moyers M, Hinshaw D, Slater J M
Radiation Medicine and Proton Treatment Facilty, Loma Linda University Medical Center, California, USA.
Invest Radiol. 1995 Apr;30(4):214-20. doi: 10.1097/00004424-199504000-00003.
Optimal dose schedules and total dose of ionizing radiation for human central nervous system malignancy are not known. An animal model has been developed for the investigation of rat central nervous system response to proton irradiation using magnetic resonance imaging (MRI). A clinical MRI device was used to monitor the response of the rat brain after irradiation as a possible indicator for histologic injury as a function of time and dose.
Single-dose fractions of protons were delivered to the left brain of 25 adult Sprague-Dawley rats. T1- and T2-weighted images were obtained using a 1.5-T MRI device via a 12-cm diameter coil at 4- to 6-week intervals after irradiation. Coronal images were evaluated by visual inspection and relaxation maps comparing the control and irradiated hemispheres. Histologic review was conducted on all rats' brains after death.
Proton irradiation was delivered successfully to only the left brain of the animals. Histologic review confirms the location and extent of tissue damage demonstrated on MRIs obtained in vivo. Statistically significant differences were seen in the T2-weighted relaxation times in the irradiated cerebral hemisphere compared with the unirradiated hemisphere.
The proton hemibrain rat model can be used to test treatment schedules of irradiation for central nervous system response using MRI to noninvasively document early and late effects within the same animal.
人类中枢神经系统恶性肿瘤的最佳电离辐射剂量方案和总剂量尚不清楚。已建立一种动物模型，用于利用磁共振成像（MRI）研究大鼠中枢神经系统对质子辐射的反应。使用临床MRI设备监测大鼠脑部照射后的反应，作为组织学损伤随时间和剂量变化的可能指标。
对25只成年Sprague-Dawley大鼠的左侧脑部给予单剂量质子照射。在照射后4至6周的间隔时间内，使用1.5-T MRI设备通过直径12厘米的线圈获取T1加权和T2加权图像。通过目视检查和比较对照半球与照射半球的弛豫图来评估冠状图像。在所有大鼠死亡后对其脑部进行组织学检查。
质子照射仅成功送达动物的左侧脑部。组织学检查证实了体内MRI显示的组织损伤的位置和范围。与未照射半球相比，照射侧大脑半球的T2加权弛豫时间存在统计学上的显著差异。
质子半脑大鼠模型可用于测试中枢神经系统反应的照射治疗方案，利用MRI在同一只动物体内无创记录早期和晚期效应。
