MNU法诱导大鼠原位膀胱癌模型的建立及MRI的诊断价值

目的：构建N-甲基亚硝基脲（MNU）诱导的大鼠原位膀胱癌模型，探讨利用磁共振成像技术（MRI）对膀胱癌模型进行无创诊断的价值。方法：60只SD雌性大鼠分为实验组45只和对照组15只。实验组大鼠定期膀胱灌注MNU，每次2mg，每2周1次，共4次。对照组大鼠同时膀胱灌注生理盐水，每次0.2mL。于第14周末麻醉大鼠后进行MRI扫描检测，检测后处死大鼠，取膀胱组织进行病理学检测。结果：实验组45只大鼠14周末存活43只，死亡2只，存活率95.6%，死亡率4.4%；经MRI扫描膀胱均见异常信号，提示肿瘤形成，与病理检查结果一致，存活大鼠成瘤率为100%。对照组15只大鼠14周末存活14只，死亡1只，存活率93.3%，死亡率6.7%；经MRI检查未发现膀胱肿瘤，病理检查未见膀胱癌，成瘤率为0。2组大鼠成瘤率比较差异有统计学意义（P < 0.05），死亡率比较差异无统计学意义（P > 0.05）。结论：MNU膀胱灌注诱导大鼠原位膀胱癌模型方法简便、可靠；MRI扫描结果与病理学检测结果一致，可作为该模型的无创鉴定方法。

Establishment of rat model of orthotopic bladder cancer induced by MNU and diagnosis value of MRI

Objective:To construct the rat models of orthotopic bladder cancer induced by N-methyl-nitrosourea (MNU),and to evaluate the value of magnetic resonance imaging (MRI)in the noninvasive diagnosis of the bladder cancer model.Methods:Sixty femail SD rats were divided into experiment group (n=45)and control group (n=15).The rats experiment group were induced with MNU (2 mg per rat)by intravesical administration every other week,for 4 times.Meantime,the rats in control group were treated with normal saline (0.2 mL per rat)by intravesical administration.At the end of the 14th week,all rats were examined by MRI and the pathological changes of bladder tissue were detected.Results:In experiment group,43 rats were alived and 2 rats were died at the end of the 14th week;the survial rate was 95.6% and the death rate was 4.4%;the abnormal signals were found in each of 43 rats by MRI which manifested as bladder tumor, and the same results were identified by pathology;the tumor formation rate was 100%.In control group,14 rats were alived and 1 rat was died at the end of the 14th week;the survival rate was 93.3%,and the death rate was 6.7%;there was no abnormal signal in the MRI examination and no bladder cancer in the pathological examination;the tumor formation rate was 0.The tumor formation rates of bladder cancer of the rats in two groups had significant difference (P <0.05),and the death rate had no significant difference (P >0.05).Conclusion:The method to establish the rat models of orthotopic bladder cancer induced by MNU is simple and reliable;the results of MRI are consistent with the pathological results and MRI examination is a reliable diagnostic method concerning this model.