兔接种VX2肿瘤的18F-FDGPET／CT观察

Observation of xenoplanted VX2 tumors in rabbits by 18F-FDG PET/CT imaging

目的:应用正电子发射断层显影术(positron emission tomography,PET)/CT研究兔接种VX2肿瘤后,不同时间的18F-氟脱氧葡萄糖(18F-fluoro-2-deoxyglucose,18F-FDG)的代谢变化,以及不同接种部位肿瘤18F-FDG代谢的差异。方法:建立VX2兔肿瘤模型,于接种后第14和19天,行PET/CT显像,观察肿瘤生长与标准摄取值(standard uptake value,SUV)的变化;根据CT测量计算肿瘤体积,取SUVmax进行统计,并计算2h肿瘤滞留指数(retention index,RI);观察肿瘤部位18F-FDG分布情况并行病理学检查,分析各组肿瘤在不同时间的体积与SUV的相关性。结果:连续动态PET/CT观察发现,VX2肿瘤生长迅速,肿瘤体积随接种时间延长逐渐增加,各组SUV随接种时间延长均呈线性升高;组间比较,不同时间点肿瘤体积(r=0.89,P<0.05)与SUV值(r=0.93,P<0.05)呈显著相关,RI在不同时间点的差异无统计学意义(P>0.05);组内比较,不同时间点的SUV值与肿瘤体积无明显相关性(P>0.05)。PET/CT和膦屏所见18F-FDG浓聚部位,经病理证实为肿瘤细胞富集区域。结论:VX2兔肿瘤模型是可用于PET/CT领域的理想动物模型;于不同部位接种,肿瘤的生长和侵袭方式相似;应用PET/CT进行放、化疗的疗效监测时,应选择在肿瘤18F-FDG代谢呈线性升高时间段进行。

Objective： To study the changes in metabolism of （18F-fluoro-2-deoxyglucose） by positron emission tomography over computed tomography （PET/CT） imaging at different time points after inoculation of VX2 tumor ceils into rabbits and determine the difference in FDG metablism between various inoculation regions. Methods： VX2 tumor cells were inoculated into rabbits. PET/CT imaging was performed at d 14 and d 19 postinoculation. The tumor growth and SUV （standard uptake value） changes were recorded. Tumor volume was defined in CT images. SUVmax was used in the calculation of retention index （RI）. The distribution of 18F-FDG was observed in tumor samples and pathological examination was performed. The correlations of tumor volume and SUV value at various time points was analyzed. Results： Continuous dynamic PET/CT imaging found that VX2 tumor grew rapidly and the volume of tumor body gradually increased with the prolongation of postinoculation time. A linear increase in SUV was observed when the postinoculation time was prolonged. The tumor volume and SUV value had significant correlation with postinoculation time （ r = 0.89, r = 0.93, P 〈 0.05 ）. However, the RI had no significant difference at various postiuoculation time points （ P 〉 0.05 ）. SUV value was not associated with tumor volume at different time points （ P 〉 0.05 ）. Pathological examination validated that the tissues with accumulation of 18-FDG were enriched with tumor cells. Conclusion： ~X2 xenografted model in rabbit is an ideal animal model for PET/CT imaging. Similar tumor growth and invasion style are observed regardless of different postinoculation days and body part, The efficacy of radiochemothery should be mornitored by PET/CT imaging in the period when the metablism of 18-FDG increases in linear.