Jirák D, Námĕstková K, Herynek V, Liscák R, Vymazal J, Mares V, Syková E, Hájek M
MR Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
Int J Radiat Biol. 2007 Apr;83(4):237-44. doi: 10.1080/09553000601169792.
Our study is focused on the magnetic resonance imaging (MRI) observation of lesion development and hippocampus related functional impairments in rats after irradiation with a Leksell Gamma knife (LGK).
We exposed 32 three-month-old Long-Evans rats to various radiation doses (25 Gy, 50 Gy or 75 Gy). The rats were scanned by a 4.7 T magnetic resonance (MR) spectrometer at several timepoints (1 - 18 months) after irradiation. The lesion size was evaluated by manual segmentation; the animals were behaviorally tested in a Morris water maze and examined histologically.
We found that a dose of 25 Gy induced no edema, necrosis or behavioral change. The response of the rats to higher doses was not uniform; the first occurrence of lesions in the rat brains irradiated with 50 and 75 Gy was detected six months post-irradiation. Functional impairment correlated well with the lesion size and histology.
Rat brains showed the development of expanding delayed lesions after 50 or 75 Gy doses from the LGK during the first year after irradiation.
我们的研究聚焦于使用Leksell伽玛刀（LGK）照射后大鼠病变发展及海马相关功能损害的磁共振成像（MRI）观察。
我们将32只3个月大的Long-Evans大鼠暴露于不同辐射剂量（25 Gy、50 Gy或75 Gy）下。在照射后的几个时间点（1 - 18个月），用4.7 T磁共振（MR）光谱仪对大鼠进行扫描。通过手动分割评估病变大小；对动物进行莫里斯水迷宫行为测试并进行组织学检查。
我们发现25 Gy的剂量未引起水肿、坏死或行为变化。大鼠对更高剂量的反应并不一致；在接受50 Gy和75 Gy照射的大鼠大脑中，首次发现病变是在照射后6个月。功能损害与病变大小和组织学密切相关。
照射后第一年，大鼠大脑在接受LGK的50或75 Gy剂量后出现了逐渐扩大的延迟性病变。
