18F-FDG PET/CT评价兔VX2肺移植瘤三维适形放疗的早期疗效

目的了解兔VX2肺移植瘤模型三维适形放疗过程中的18F-FDG PET/CT显像特点,探讨18F-FDG PET/CT评估肿瘤放疗疗效的价值。方法建立16只兔VX2肺移植瘤模型,按随机数字表法分为放疗组和对照组,每组各8只,分别于三维适形放疗累积剂量达06、、121、8 Gy时行18F-FDG PET/CT检查,采集不同时期两组模型兔肺部肿瘤延迟最大标准摄取值(SUVmax)、对侧正常肺组织SUVmax及两者的比值(T/L),观察两组模型兔T/L及肿瘤体积变化情况;放疗结束后,取出两组模型兔肺部肿瘤,常规HE染色。结果放疗组模型兔累积照射剂量达0、6、12、18 Gy时,T/L分别为(8.447±1.488)(、9.344±1.342)、(7.143±1.307)(、6.221±1.066),各时间点依次比较,差异均有统计学意义(t=3.679、5.010、5.984,P均<0.05),而对照组相应时间T/L逐渐升高,分别为(8.428±1.705)(、9.610±1.282)(、10.402±1.283)(、11.586±1.627),各时间点依次比较,差异均有统计学意义(t=3.360、3.2252、.611,均P<0.05);两组模型兔肺部肿瘤体积均有增长,累积剂量达6、12、18 Gy组间分别比较,差异用统计学意义(t=2.7425、.225、6.824,均P<0.05),放疗组肿瘤体积增长速度明显慢于对照组。HE染色示放疗组肿瘤组织内大片糜烂坏死,对照组肿瘤组织内坏死灶不明显。结论兔VX2肺移植瘤三维适形放疗过程中行18F-FDGPET/CT显像动态观察,T/L短期内显著降低,可在CT形态学改变之前评估放疗早期疗效。

Evaluation of the early reaction of three-dimensional conformal radiotherapy in rabbit lung VX2 transplant tumor by 18 F-FDG PET/CT

Objective To study the characteristics of 18F-FDG PET/CT imaging in rabbit lung VX2 transplant tumor during three-dimensional conformal radiotherapy, and to explore the value of 18 F-FDG PET/CT to assess the efficacy of tumor radiotherapy. Methods Six- teen tumor-bearing rabbits were evenly and randomly divided into 2 groups （8 rabbits in each group ） ： radiotherapy group and control group, 18 F-FDG PET/CT imaging was performed when radiation cumulative dose achieved 0,6,12 and 18 Gy. The delayed tumor tissue SUVmax （maximum standardized uptake value）, the contralateral lung tissue SUVmax, the ratio of the two（T/L） and the change of tumor volume were monitored by 18F-FDG PET/CT. The rabbits in each group were sacrificed after 18F-FDG PET/CT imaging, HE Staining observing the change of pathology. Results When radiation cumulative dose achieved 0,6,12 and 18 Gy, T/L of tumor-bearing rabbits in radiotherapy group were （8. 447 ± 1. 488 ）, （9. 344 ± 1. 342 ）, （7. 143 ± 1. 307 ）, （6.221 ± 1. 066 ）. The differences at each time were statistically significant （ t = 3. 679,5. 010,5. 984, all P 〈 0.05 ）. T/L of tumor-bearing rabbits in control group gradually increased ： （ 8. 428 ± 1. 705 ）, （9. 610 ± 1. 282）, （ 10.402 ± 1. 283）, （ 11. 586 ± 1. 627）. The differences at each time were statistically significant（t = 3. 360,3. 225,2.611, all P 〈 0.05 ）. Tumor volume grew in two groups, When radiation cumulative dose achieved 6,12 and 18 Gy, tumor volumes of each group were statistically significant （2.742,5. 225,6. 824, all P 〈 0. 05 ） , however tumor volume growth in radiotherapy group was slower than that in control group. HE staining showed large areas of necrosis within the tumor tissue of the radiotherapy group, and the activity of tumor ceils was significantly less in the control group. Conclusion 18F-FDG PET/CT imaging in rabbit lung VX2 transplant tumor during three-dimensional conformal radiotherapy showed T/L significantly reduced in a short time, which can evaluate the early reaction of radiotherapy before morphology changes.