MR扩散加权成像在肾癌微波消融术后随访中的应用价值

The value of MR diffusion-weighted imaging in follow-up studies of renal cell carcinoma after microwave ablation

目的探讨磁共振扩散加权成像(DWI)在评价肾癌微波消融(MWA)术后疗效的价值。方法回顾性分析33个肾癌病灶在MWA治疗后1天、1个月、3个月和6个月及以上的DWI信号变化特点和ADC值变化规律。结果术后1天,完全消融区DWI呈低信号,周围伴有高信号的环形反应带;1个月时周围环形反应带变薄,3个月基本消失,消融灶呈混合信号。残留和局部进展组织表现为位于消融区和正常肾组织之间的不规则环状或结节状稍高信号。在b值为800s/mm^2时,术前与术后不同时间、不同组织间的ADC值变化显示:1)肾癌ADC值低于正常肾脏;2)术后完全消融区与术前比较有显著差异,ADC值降低并且呈现逐渐降低的趋势;3)术后各随访时间完全消融区、周围环形反应带、正常肾实质不同组织间的ADC值差异均有统计学意义;4)残留/局部进展组织的ADC值与术前肾癌的ADC值间没有差异。结论DWI能有效区分完全坏死区、活性肿瘤组织和正常肾实质,提供比MR常规扫描更多的诊断信息,在肾癌微波消融疗效评估中发挥重要作用。

Objective To investigate the value of magnetic resonance diffusion-weighted imaging(DWI)in evaluating the curative effect of renal cell carcinoma(RCC)after microwave ablation(MWA).Methods The characteristics of MR DWI signals and ADC values of 33 RCC lesions after MWA for 1 day,1 month,3 months and 6 months more were analyzed.Results The first day after the operation,DWI in the complete ablation zone showed hypo intense and the surrounding annular reaction zone was accompanied by hyperintensity.The peripheral annular reaction zone became thinner in January and basically disappeared in 3 months.Lesions treated by MWA displayed mixed signals on DWI after 1 month.The residual and locally progressive tissues showed irregular annular or nodular slightly hyperintense signals between ablation area and normal kidney tissue.When the b value was 800 s/mm^2,ADC values changes between different tissues at different time pre-and post-ablation showed that:1)The ADC values of RCC is lower than that of normal renal tissue;2)The lesions after ablation was significantly different from that before the ablation.The ADC values decreased and gradually tended to decrease;3)The ADC values of different tissues(lesions,peripheral annular reaction zone,normal renal tissue)at the different follow-up times after operation were statistically significant;4)There was no difference between ADC values of residual/locally progressive tissues and those of RCC before the operation.Conclusion DWI can effectively differentiate the completely necrotic region,the active tumor tissue and the normal renal tissues.It can also provide more diagnostic information than the conventional MRI,and play an important role in evaluating the efficacy of MWA of RCC.