基于PET-CT与4DCT的NSCLC的PTV比较

Comparison of PTV based on FDG PET-CT versus 4DCT in non-small cell lung cancer

目的 比较NSCLC基于FDG PET-CT与4DCT定义的原发肿瘤PTV间位置及体积差异.方法 15例NSCLC患者序贯完成胸部3DCT、4DCT及FDG PET-CT扫描.在4DCT 10个呼吸时相图像上勾画原发肿瘤GTV并融合获得IGTV10.基于PET图像原发肿瘤SUVmax的15％勾画靶区定义为IGTVPET.分别基于ICTV10、IGTVPET外扩10mm得到PTV4D和PTVPET.比较PTV PET与PTV4D间位置、体积及DI值差异.结果 PTV PET和PTV4D中心点位置差异无统计学意义（P=0.589、0.147、0.096）.PTVPET和PTV4D体积差异无统计学意义（P=0.156）,但5例PTV PET相对于PTV4D变化率＞20％,10例PTVPET＞ PTV4D,平均增加30％,5例PTVPET＜ PTV4D,平均减少11％.PTV4D对PTVPET的DI平均值为85％,有7％ ～ 46％的PTVPET未能被PTV4D所覆盖;PTV PET和PTV4D间的DI同三维运动矢量无相关性（P=0.134、0.405）.结论 尽管基于FDG PET-CT与基于4DCT所构建NSCLC原发肿瘤PTV中心点位置及体积差异并不显著,但相互DI值所反映的两靶区空间错位明显且这种错位与肿瘤位移大小并无相关性.

Objective To compare the positional and volumetric differences of planning target volumes （PTVs） based on fluorodeoxyglucose （FDG） positron emission tomography/computed tomography （PET-CT） and four-dimensional CT （4DCT） for the primary tumor of non-small cell lung cancer （NSCLC）.Methods Fifteen patients with NSCLC sequentially underwent three-dimensional CT（3DCT）,4DCT,and FDG PET-CT scans of the thorax.IGTV10 was defined on 10 respiratory phases of 4DCT images; IGTVPET was defined on PET-CT images using a fixed threshold of 15％ of the maximum standard uptake values.PTV4D and PTVPET were obtained by adding a 10 mm margin around IGTV10 and IGTVPET.The differences in volume,position,and degree of inclusion （DI） between PTVPET and PTV4D were evaluated.Results There was no significant difference in centroid position between PTVPET and PTV4D （P =0.589,0.147,and 0.096）.There was no significant difference in volume between PTVPET and PTV4D （P =0.156） ;however,PET-CT resulted in an ＞ 20％ change in PTV in 5 of 15 patients,the PTVPET volumeincreased （average 30％） in 10 patients,and the PTVPET volume decreased （average 11％） in 5 patients.The mean DI of PTV4D in PTVPET was 85％,and 7％-46％ of PTVPET was not included within the PTV4D.The DI between PTV4D and PTVPET showed no significant correlation with the 3D motion vector （P =0.134 and 0.405）.Conclusions Although there are no significant differences in centroid position and volume between PTVPET and PTV4D for the primary tumor of NSCLC,the spatial mismatch between them is apparent and the mismatch shows no correlation with tumor displacement.