大鼠C6胶质瘤放射治疗前后^(18)F-FDG PET/CT显像及病理学变化

Correlative study of ^(18)F-FDG PET/CT imaging and pathological changes of rat C6 glioma after radiotherary

目的:研究大鼠C6胶质瘤放射治疗后18F-脱氧葡萄糖(18F-FDG)PET/CT显像及组织病理学变化,观察放疗后肿瘤组织的演化过程,探讨C6胶质瘤放疗后不同时间点FDG摄取水平变化与病理学变化间的关系。方法:30只雄性SD大鼠右腿皮下种植C6胶质瘤,2周后全部成瘤,将大鼠按随机数字表分为A、B、C三组,每组10只,A组为对照组,仅行18F-FDG PET/CT显像,B、C两组行放射治疗并分别在治疗后48 h及1周进行显像,观察肿瘤与对侧脊柱旁肌肉的最大标准摄取值(SUVmax)比值(T/M)及肿瘤体积的变化。显像后取出肿瘤组织分别行病理切片观察肿瘤细胞的坏死及萎缩情况,并进行免疫组织化学切片计数微血管密度(MVD)。结果:A、B、C三组T/M逐渐减低,分别为10.86±3.31、9.23±4.56和5.16±2.52,统计检验表明A、B组间差异无统计学意义(P>0.05),而A、C组间差异具有统计学意义(P<0.05)。病理结果表明随着放疗后时间的延长,肿瘤坏死成分逐渐增多,体积逐渐减小,A组[(8.61±6.57)cm3]、B组[(7.80±7.31)cm3]间差异无统计学意义(P>0.05),A、C组[(5.21±5.48)cm3]间差异则具有统计学意义(P<0.05)。免疫组化结果显示B组MVD(19.5±1.96)较A组(17.9±2.02)轻度增高,组间差异无统计学意义(P>0.05),C组MVD(8.4±1.84)显著下降,与A组差异具有统计学意义(P<0.05)。相关性分析表明A、C组间T/M变化与肿瘤体积及MVD变化呈正相关(r分别为0.83、0.68,P值均<0.05),而A、B组间T/M变化仅与肿瘤体积变化相关(r=0.76,P<0.05)。结论:大鼠C6胶质瘤放射治疗后,FDG摄取水平变化在放疗后48 h仅与肿瘤体积变化相关,放疗后1周则能有效反映肿瘤的病理学改变。

Objective：To study the correlation of 18F-fluorodeoxyglucose（^18F-FDG） PET/CT imaging with pathological changes of rat C6 glioma after radiotherapy.Methods：Thirty C6 glioma-bearing male SD rats were randomly divided into three groups（10 rats in each group）,group A,B and C,and imaged with FDG PET/CT two weeks after inoculation of tumor cells,48h and one week after radiotherapy respectively.The ratios of SUVmax of tumor to muscles（tumor-to-muscle,T/M） and tumor volume were calculated.All rats were sacrificed after FDG PET/CT imaging for pathology and immunohistochemistry studies.Results：T/M of group B（9.23±4.56） was mildly reduced compared with group A（10.86±3.31）,while group C（5.16±2.52） was significantly decreased compared with gropu A（P〈0.05）.The amount of tumor necrosis increased with time after radiotherapy,tumor volume decreased gradually,the differentces between group A and C were significant [（8.61±6.57）cm3 vs（5.21±5.48）cm3].Microvessel density（MVD） of group B（19.5±1.96） increased slightly compared with group A（17.9±2.02）,MVD of group C（8.4±1.84） was significantly decreased compared with that of group A（P〈0.05）.Correlation analysis showed that changes of T/M between group A and C were positively correlated with tumor volume and MVD（r=0.83,0.68,all P〈0.05）;while changes of T/M between group A and B were only positively correlated with tumor volum（r=0.76,P〈0.05）.Conclusion：The changes of 18F-FDG uptake of rat C6 glioma in the early 48h after radiotherapy were only relevant to tumor volume,but were closely related to pathological changes one week later.