基于PET/CT选定阈值与基于4D-CT呼气末时相所勾画非小细胞肺癌原发肿瘤靶区相关性分析

摘要

Objective To investigate the correlations in target volumes based on positron emission tomography CT (PET/CT) and the end-expiration phase of four-dimensional CT (4D-CT) images for non-small cell lung cancer (NSCLC).Methods Seventeen patients with NSCLC sequentially underwent three-dimensional CT (3DCT),4D-CT and 18F-FDG PET/CT thoracic simulation scans.The gross target volume (GTV) was contoured on the end-expiration phase (50％) of 4D-CT and defined as GTV50％.The internal gross target volumes (IGTV) based on PET/CT images (IGTVPET) were determined by the standardized uptake value (SUV) 2.0 (IGTVPET2.0) and 20％ percentage of the maximal standardized uptake value (SUVmax) (IGTVPET20％).The following parameters were calculated to analyze the correlation between IGTVPET and GTV50％ in volume ratio (VR) and conformity index (CI):maximum transverse diameter of GTV50％,volume of GTV50％,the displacement of GTV in the cranial-caudal direction and 3D Vector calculated from 4D-CT dataset as well as the SUVmax.Results There was no significant correlation between the VR of IGTVPET2.0 to GTV50％ and the maximum transverse diameter of GTV50％,volume of GTV50％,the displacement of GTV in the cranial-caudal direction,3D Vector and the SUVmax (P ＞ 0.05).The VR between IGTVPET20％ and GTV50％ inversely related to maximum transverse diameter of GTV50％,volume of GTV50％ and SUVmax (r =-0.663,-0.669,-0.752,P ＜0.05).The CI between IGTVPET2.0 and GTV50％ positively related to volume of GTV50％ and maximum transverse diameter of GTV50％ (r =0.613,0.483,P ＜ 0.05).Conclusions 3D PET images provide a time-averaged image of the tumor during the numerous breathing cycle.They fail to include the full information of moving tumor.The target volumes based on 3D PET might not reflect the real IGTV of NSCLC.%目的 探讨基于PET/CT图像选定阈值与基于4D-CT呼气末时相图像所勾画的非小细胞肺癌(NSCLC)原发肿瘤靶区相关性因素.方法 入组NSCLC患者序贯完成3DCT、4D-CT、18F-FDG PET/CT胸部定位扫描.基于4D-CT呼气末时相(50％)图像勾画原发肿瘤大体肿瘤体积(GTV50％).基于PET图像原发肿瘤标准摄取值(SUV)≥2.0、SUV最大值(SUVmax)的20％勾画内大体肿瘤体积(IGTV)分别命名为IGTVPET2.0、IGTVPET20％.分析IGTVPET2.0、IGTVPET20％与GTV50％的体积比(VR2.0、VR20％)及适形指数(CI20、CI20％)与GTV50％最大横径、GTV50％体积大小、GTV头脚方向位移、GTV三维运动矢量及SUVmax的相关性.结果 VR2.0和GTV50％最大横径、GTV50％体积大小、GTV头脚方向位移、GTV三维运动矢量及SUVmax均无相关性(P ＞0.05);VR20％和GTV50％体积大小、GTV50％最大横径及SUVmax呈负相关(r=-0.663、-0.669、-0.752,P＜0.05).CI2.0和GTV50％体积大小、GTV50％最大横径呈正相关(r=0.613、0.483,P＜0.05).结论 3D PET图像是包含了多个呼吸周期的中位图像,未能包含肿瘤的全部运动信息,基于3D PET/CT图像所构建的靶区不能准确地代表NSCLC的IGTV.