18F-FDG 18F-FLT PET显像评价肺腺癌放射治疗疗效的实验研究

  目的  评价18F-FDG和18F-FLT PET显像在早期评价肺腺癌放射治疗疗效中的作用。  方法  40只A549荷肺腺癌小鼠随机分为对照组、5 Gy组、10 Gy组、15 Gy组和30 Gy组共5组, 分别对5个剂量组的荷A549裸鼠模型于放疗前1天和放疗后3天、1周、2周和4周行18F-FDG和18F-FLT PET显像, 测量移植瘤大小、SUV值和T/N值。显像后每组随机处死2只裸鼠, 行移植瘤免疫组化法检测Ki-67及TK-1表达。分析裸鼠移植瘤放疗前后18F-FDG、18F-FLT PET-CT显像T/N值变化及其与Ki-67表达的相关性。  结果  放疗前荷瘤裸鼠18F-FDG、18F-FLT PET-CT显像均可清晰显示移植瘤, 据其T/N值（均>1.5）可作出正确诊断。Ki-67、TK-1阳性表达率随放疗时间延长和放疗剂量增加而降低。18F-FDG、18F-FLT PET-CT显像T/N值与反应细胞增殖状况的指标Ki-67表达具有较好的相关性。18F-FLT PET-CT显像T/N值与增殖指标Ki-67及TK-1表达相关程度优于18F-FDG。  结论  接受照射后, 18F-FLT在肿瘤内的摄取变化可以反映肿瘤细胞的增殖状态, 18F-FLT PET-CT显像可以用于肺腺癌放射治疗效果早期评价。 

Experimental Research of 18F-FDG and 18F-FLT PET on Therapeutic Response in Radiotherapy for Pulmonary Adenocarcinoma

  Objective  This study aims to evaluate early the efficacy of 18F-FLT and 18F-FDG PET/CT imaging systems in assessing the tumor response of radiotherapy for pulmonary adenocarcinoma.  Methods  A total of 40 A549 xenografts with human pulmonary adenocarcinoma were treated with different dosages (0, 5, 10, 15, and 30 Gy) of X-ray irradiation (radiotherapy). Changes in tumor volume during the entire experimental period were observed. 18F-FDG and 18F-FLT PET/CT imaging systems were employed before radiotherapy and at 3 d, 1 week, 2 weeks, and 4 weeks after radiotherapy. SUVmax and T/N were analyzed. Immunohistochemical analysis of the xenografts was conducted to detect the proliferation expression of Ki-67. The T/N values of the 18F-FDG and 18F-FLT PET/CT imaging systems and the corresponding indexes of Ki-67 before and after radiotherapy were compared.  Results  Both imaging systems identified the xenografts before irradiation and distinguished malignancy according to the T/N values (T/N>1.5) of xenografts. The positive expression rates of Ki-67 decreased as the radiation time was prolonged and as the dosage was increased. The T/N values of the xenografts in the 18F-FDG and 18F-FLT PET/CT images of each time point were correlated with the positive expression rates of Ki-67. The correlation in 18F-FLT PET/CT imaging was better than that in 18F-FDG imaging.  Conclusion  Changes in 18F-FLT uptake reflected proliferation. 18F-FLT PET/CT imaging can be used for the early evaluation of radiotherapy for pulmonary adenocarcinoma.