血源性兔VX2肿瘤脑及脑膜转移瘤动物模型的建立及MRI检测

目的：研究MRI对血源性脑及脑膜转移瘤动物模型转移灶的检出效果。方法：18只新西兰大白兔随机分为3组，分别从左颈总动脉内接种VX2瘤细胞，A组：20％甘露醇注入5min后接种VX2瘤细胞：B组：20％甘露醇注入5min后，加入肝素再接种VX2瘤细胞；C组，对照组，单纯注入等量生理盐水。术后2周后行MRI检查。病理取材HE染色光镜下观察。结果：平扫：A组，1只（1／6）发现脑内结节并脑膜结节样增厚，T1WI为等信号，T2WI为稍高信号。B组，2只（2／6）为脑内多发结节，T1WI为等信号，TM为稍高信号。2只（2／6）脑膜结节样增厚。增强扫描：A组，2只（2／6）脑内见强化结节灶；直径在1．5mm-7．0mm之间。4K（4／6）脑膜线样增厚或结节样增厚强化。B组，6只（6／6）脑内见直径在1．5mm-5．0mm的高信号结节，其中5只为脑内多发结节灶；4只（4／6）脑膜线样或结节样增厚强化，左侧为主，其中2只（2／6）为双侧脑膜增厚。增强扫描A、B组问脑内病灶差异有统计学意义（Fisher’s确切概率值为0．04）。C组平扫及增强扫描均未见异常信号。结论：上述方法制成的动物模型可为医学影像学研究提供可靠的动物模型，加入肝素可提高瘤灶的形成几率，并证实血脑屏障对脑转移瘤的形成起重要作用。MRI增强检查是检出脑内及脑膜转移瘤的首选方法。

Establishment of VX2 Tumor Animal Model of Haematogenous Cerebral and Meningeal Metastasis in Rabbits and Its 3.0T MRI Study

Objective： To introduce a method of establishing a hematogenous cerebral and meningeal animal model, and to ana- lyze the MRI study of model. Methods： 18 New-zealend rabbits were divided into 3 groups. The rabbits in group A were inoculated with 20 % mannitol and VX2 tumor cell, and rabbits in group B were inoculated with 20 % mannitol, heparin and VX2 tumor cell. The last group was inoculated with saline only. MRI plain and enhanced scan were given after two weeks. Pathological study was made under mi- croscope by HE stain. Results： Plain scanning： group A： one of them was found brain multiple nodules and meningeal nodular thicking, which showed a low signal on T~ weighted imaging and a high signal on T2 weighted imaging. Group B, two rabbits were found brain metastasis, which showed a low signal on T~ weighted imaging and a high signal on T2 weighted imaging. Two of them were meningeal nodular thickening. Enhance scanning： group A, two of them （2/6） had enhanced lesions within the brain in diameter of 1.5- 7.0 mm; four of them （4/6） had a nodular or linear thickening and enhancement. Group B, six rabbits （6/6） had a high signal lesions within the brain in diameter 1.5 mm - 5.0 mm, five of them had multiple nodules. Four of them （4/6） had nodular or linear thickening and enhancement in the left meninge, two of them （2/6） were bilateral meningeal thickening. The result of Fisher exact test for enhancement scanning A and B was 0.04 （P〈0.05）. The animals in Group C were not found abnormal sigals from both plain scanning and enhancement results. Conclusion： The above method for establishing animal model could provide a good model for medical imaging study, and the use of heparin could im- prove the probability of tumor lesion. It was confirmed that the BBB played an important role for cerebral metastasis, and the high field MR had some advantages for the detection of cerebral metastasis. MRI contrast administration was the first choice for detection cerebral and meningeal metastasis.