DW-MRI评价裸鼠结肠癌异体移植瘤化疗效果的研究

摘要

Objective: To assess early chemotherapuetic response in a mouse colon cancer model using diffusion weighted imaging(DWI) shown as apparent diffusion coefficient(ADC) and analyze the potentially associated histopathologic characteristics. Materials and Methods: Thirty-two Athymic mice bearing HCT116 xenografts on right rear flank were allocated into four groups: control, 5Fu, oxaliplatin and 5 -Fu/oxaliplatin combined. Mice were undergone body MR examination, including T2-weighted, T,-weighted and DW MR imaging, before and 3, 7, 11, 20 days after treatment. Changes in ADC and volume of tumors were recorded and calculated. At each time point after chemotherapy, histopathological characteristics were recorded and analyzed. The correlations between changes in ADC and histopathological characteristics at each time point were analyzed. Results: the mean ADC value in each group decreased 3 days after initialization of therapy which may be associated with cell swelling without necrosis. Seven and eleven days after initialization of therapy, mean tumor ADC value in groups treated with oxaliplatin and 5-Fu/oxaliplatin combined increased and significances were seen (P<0.05). For the group treated only with 5Fu, the mean ADC values 7 to 11 days after initialization of therapy increased but no significance was seen(p=0.07). Necrosis within tumor was detected 7 and 11 days after chemotherapy. However, no significant difference in ADC values between 20 days after and before therapy was shown. Regeneration in tumor was detected 20 days after chemotherapy. Conclusions: DWI shown as ADC values increased has a potential in early prediction of response to chemotherapy.%目的:评估扩散加权磁共振成像(DW-MRI)早期检测裸鼠结肠癌异体移植瘤化疗效果的价值,探讨表观扩散系数(ADC)变化规律与同期病理改变的关系.材料和方法:HCT116人结肠癌细胞接种于32只无胸腺裸鼠右侧腋下.将荷瘤裸鼠分为:空白对照组、5-Fu单药组、oxaliplatin单药组和5-Fu/oxaliplatin联合用药组(n=8).治疗前及治疗后第3、7、11、20天采集T2,T1和DW加权图像后,记录肿瘤体积值和ADC值,并与同期组织学改变对照分析.结果:治疗后7～11天,肿瘤ADC值的增加与平均倍增时间呈正相关(r=0.86,P<0.05).各组治疗后3天,肿瘤ADC值均不同程度下降,病理显示肿瘤组织充血、细胞肿胀.除接受5Fu(P=0.07)单药治疗组,其余各组治疗后7～11天显示肿瘤ADC值增加(P<0.05),病理证实肿瘤组织坏死.治疗后20天,各个组ADC值再次下降,与治疗前无差异(P>0.05),病理结果示肿瘤再生.结论:DW影像所示ADC值动态变化可被作为早期检测结肠癌化疗效果的定量指标.