联合应用DCE-MRI和^(18)F-FDG PET/CT监测^(125)I粒子短距离放疗对胰腺癌移植瘤的疗效

Combining DCE-MRI and ^(18)F-FDG PET/CT for monitoring the efficacy of ^(125)I seed brachytherapy in nude mice bearing pancreatic cancer xenografts

目的:评估动态对比增强磁共振(DCE-MRI)和通过^(18)Fluorine-fluorinedeoxyglucose作为示踪剂的正电子发射型体层摄影术-X线计算机体层摄影图像融合(^(18)F-FDG PET/CT)监测^(125)I粒子短距离放疗对胰腺癌移植瘤的疗效。方法:16只胰腺癌裸小鼠被随机分为^(125)I粒子植入组(n=8)和空载粒子组(n=8)。于治疗前及治疗后第10天分别进行DCE-MRI和^(18)F-FDG PET/CT检查。DCE-MRI灌注成像参数包括容量转移常数(Ktrans)、速率常数(Kep)、血管外细胞外间隙容积比(Ve)。^(18)F-FDG PET/CT测量最大标准摄取值(SUVmax)和平均标准摄取值(SUVmean)。结果:^(125)I粒子植入组与对照组相比,Ktrans、Kep、SUVmax和SUVmean均明显降低(P=0.000,P=0.000,P=0.003,P=0.001)。DCE-MRI灌注参数与标准化FDG摄取值之间不存在相关性。结论:DCE-MRI和^(18)F-FDG PET/CT监测^(125)I粒子短距离放疗对胰腺癌移植瘤的疗效是可行的。肿瘤血流动力学改变及糖代谢之间可能是相对独立因素,两种成像方法提供互补信息。

Objective To assess the value of dynamic contrast-enhanced magnetic resonance imaging（DCE-MRI） and positron emission tomography- computed tomography with the tracer agent of -（18）fluorine- fluorinedeoxyglucose（-（18）F- FDG PET/CT） in evaluating the response of pancreatic cancer xenografts to-（125）I seed brachytherapy. Methods Sixteen nude mice bearing pancreatic cancer xenografts were randomly treated with-（125）I seeds（n=8） or empty seeds（n=8）. DCE-MRI and -（18）F-FDG PET/CT examinations were performed before and at 10 days after the treatment to assess the therapeutic effect by measuring DCEMRI perfusion parameters including the volume transfer constant between blood plasma and extravascular extracellular space（Ktrans）, fractional extravascular extracellular space per unit volume of tissue（Ve）, and the rate constant between extravascular extracellular space and blood plasma（Kep） and -（18）F-FDG PET/CT parameters including the maximum standardized uptake value（SUVmax） and mean standardized uptake value（SUVmean） of the tumor. Results Compared with the control group, the mice treated with-（125）I seed brachytherapy showed significantly decreased Ktrans（P=0.000）, Kep（P=0.000）, SUVmax（P=0.003） and SUVmean（P=0.001） in the tumor. DCE- MRI perfusion parameters were not correlated with standardized FDG uptake values.Conclusion DCE-MRI and -（18）F-FDG PET/CT are feasible to monitor the response of pancreatic cancer xenografts to-（125）I seed brachytherapy. The tumor blood flow and glucose metabolism are probably independent predictors, and DCE- MRI and -（18）F-FDG PET/CT can be complementary in assessing the therapeutic effect of brachytherapy.