Abstract:

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.

Key words: disease model, animals, bladder neoplasms, N-methyl-nitrosourea, magnetic resonance imaging, identification of living body