18F-FLT和18F-FDG PET显像评价肺腺癌放射治疗疗效研究

摘要

Objective: To evaluate the early efficacy of 18F-FLT and 18F-FDG PET imaging in assessing the tumor response of radiotherapy for lung adenocarcinoma. Methods: Eighteen mice bearing the lung adenocarcinoma were randomly divided into two groups according to the different tracers (18F-FLT and 18F-FDG), every group was divided into three parts, the first and second groups were treated with 6 Mv X-ray irradiation of 2000 cGy one fraction in the first and second day before the experiment , the third was control group. All mice were injected with 18F-FLT or 18F-FDG by tail vein. At 30 min after tracers injection, body distribution and PET imaging were performed. Results:The body distribution study in murine model of lung adenocarcinoma shows considerable uptake of 18F-FLT and 18F-FDG in tumor was observed. The ratio of tumor to muscle, tumor to lung were all above 2.18F-FLT uptake in murine model of lung adenocarcinoma after irradiation was significantly lower than that of control group. PET imaging after radiotherapy shows the T/NT value of FLT group was significantly lower than the control group after 24 h, 48 h(t=2.017, P<0.05). Conclusion: Our experimental studies shows that the uptake of 18F-FLT in pulmonary malignant tissues is higher than that in normal tissues, thus the pulmonary neoplasm can be identified accurately with PET imaging. The decrease in tumor 18F-FLT uptake after radiotherapy was more pronounced than that of 18F-FDG. Therefore, 18F-FLT is a promising PET tracer for monitoring response to radiotherapy in oncology.%目的：评价3'-脱氧-3'-18F-氟代胸苷(18F-FLT)和18F-氟代脱氧葡萄糖(18F-FDG)PET早期肺腺癌显像在放射治疗疗效中的作用。方法：将18只荷肺腺癌小鼠随机分为18F-FLT组和18F-FDG组，各组又随机配对分为A、B、C3组，每组3只。A组为对照组，未进行任何治疗；B组于实验前1d采用异氟醚麻醉后，固定于直线加速器下，对小鼠肿瘤部位进行放射治疗，单次剂量2000 cGy，能量6 MV，射线类型为X射线；C组于实验前2 d同样对小鼠肿瘤部位进行放射治疗，操作方法及放射治疗剂量同B组。经小鼠尾静脉注入18F-FLT和18F-FDG后行MicroPET显像，并处死小鼠取各器官用井形探测仪测定生物分布。结果：荷肺腺癌小鼠的生物分布研究中发现，肿瘤部位18F-FLT及18F-FDG摄取较高，肿瘤对肌肉及肺的T/NT比值均＞2，18F-FLT及18F-FDG PET对肿瘤显像清晰。放射治疗后肺腺癌18F-FLT摄取较对照组明显降低，而18F-FDG摄取变化不明显。PET显像18F-FLT组在放射治疗24 h和48 h后T/NT值明显降低且与放射治疗前对比有明显差异(t=2.017，P＜0.05)。18F-FDG组则无明显差异。结论：18F-FLT可被肺部恶性肿瘤摄取，其特异度高于18F-FDG。放射治疗引起的18F-FLT摄取变化较18F-FDG灵敏，放射治疗后18F-FLT摄取降低较18F-FDG明显，因而18F-FLT是一种监测恶性肿瘤放射治疗疗效的有效示踪剂。