弥散成像评价兔软组织VX2肿瘤细胞增殖的价值

Evaluation of cell proliferation of rabbit VX2 soft-tissue tumor cells by diffusion weighted imaging

目的：分析反映兔软组织VX2肿瘤细胞增殖情况Ki-67标记指数与由弥散加权影像（DWI）计算出表观弥散系数（ADC）的相关性。方法：将VX2肿瘤接种于18只健康新西兰大白兔右侧后腿肌肉内,34周后对实验用兔行DWI检查。利用MR扫描仪上的软件对所获DWI图像进行处理生成ADC图,测量在肿瘤内所选24个感兴趣区（ROI）的ADC值。随后处死实验用兔,获取肿瘤标本,在与ADC图的ROI相对应非坏死区进行取材,对所获肿瘤组织行Ki-67免疫组化染色后测量Ki-67标记指数。利用Spearman相关分析法评价VX2肿瘤组织Ki-67标记指数与ADC值的相关性。结果：所有实验用兔的VX2肿瘤种植成功率为100%。在进行DWI检查前,1只实验用兔因麻醉意外死亡,另1只于饲养过程中不明原因死亡。总共分析了39块VX2肿瘤组织,其Ki-67标记指数与ADC值呈显著负相关,r=-0.873,P〈0.001。结论：ADC值通过反映Ki-67标记指数可用于评价软组织肿瘤的细胞增殖情况,从而帮助判断预后、指导治疗并监测疗效。

OBJECTIVE： To evaluate the relationship between the Ki-67 labeling indices,which reflect the cell proliferation of VX2 tumor in the soft tissue of rabbit,and ADC values generated from MR diffusion weighted imaging（DWI）.METHODS： VX2 tumor was inoculated in the muscular tissue of right posterior limbs of 18 healthy New Zealand white rabbits,on which DWI was performed 3 to 4 weeks later.Apparent diffusion coefficient（ADC） maps were generated from DWI images using the software on MR scanner.ADC values were measured in 2-4 regions of interest（ROIs） for each tumor.The rabbits were sacrificed after MR imaging.The gross specimens of tumors were obtained and tumor tissues were taken from the non-necrotic regions corresponding to ROIs on DWI images.Ki-67 immunostaining of obtained tumor tissues was performed to measure their Ki-67 labeling indices.The correlation between ADC values and Ki-67 labeling indices was evaluated by Spearman correlative analysis.RESULTS： VX2 tumor was implanted on all experimental rabbits successfully.Before the performance of DWI examination,one experimental rabbit was died due to an anesthesia accident,and another one due to an unknown reason during feeding.Totally 39 pieces of VX2 tumor tissues were analyzed.There was a significant negative correlation between their Ki-67 labeling indices and ADC values（r=-0.873,P〈0.001）.CONCLUSION： ADC value can be used in evaluating the cell proliferation of soft tissue tumor through its reflection of Ki-67 labeling index,and therefore is helpful in evaluating the prognosis of soft tissue tumor,making plan for their treatment and monitoring the effect of their therapies.