4DCT全时相与PET-CT不同SUV阈值勾画胸段食管癌IGTV的比较研究

目的 比较基于4DCT 10个时相与基于PET-CT不同SUV值勾画的IGTV的大小和CI、DI值。方法 15例胸段食管癌患者序贯完成3DCT、4DCT、FDG PET-CT 胸部定位扫描。在4DCT各时相图像上分别勾画IGTV并融合获得IGTV₁₀。基于不同SUV值(≥2.0、2.5、3.0、3.5)及 SUV_max的不同百分比(≥20%、25%、30%、35%、40%)分别在PET图像上勾画IGTV_PET2.0、IGTV_PET2.5、IGTV_PET3.0、IGTV_PET3.5、IGTV_PET20%、IGTV_PET25%、IGTV_PET30%、IGTV_PET35%、IGTV_PET40%。两两比较采用配对t检验,靶区中心间距与CI、DI值相关性采用Pearson法分析。结果 IGTV_PET2.5、IGTV_PET20%与IGTV₁₀体积相近(体积比0.92、1.08,P=0.985、0.886),IGTV_PET2.0、IGTV_PET2.5、IGTV_PET20%与IGTV₁₀间CI值也相近(0.53、0.52、0.53,P=0.432,1.00,0.414),但三者均明显大于其他6个IGTV_PET与IGTV₁₀间的CI值(0.33~0.50,P=0.000~0.047)。IGTV_PET2.5对IGTV₁₀的DI (0.74)与IGTV_PET20%对IGTV₁₀的DI (0.72)也相近(P=0.542),IGTV₁₀对IGTV_PET2.5的DI (0.67)与IGTV₁₀对IGTV_PET20%的DI也相近(P=0.539)。结论 SUV阈值为2.5及最大值的20%时,基于PET-CT勾画的IGTV_PET与基于4DCT 10个时相构建的IGTV₁₀体积大小接近且空间错位程度相对较小。

Comparison between IGTVs based on ten phases of 4DCT and nine PET-CT SUV thresholds in primary thoracic esophageal cancer

Objective To compare the volume, conformity index (CI), and degree of inclusion (DI) between internal gross tumor volumes (IGTVs) delineated based on ten phases of four-dimensional computed tomography (4DCT) and nine positron emission tomography (PET)-CT standardized uptake value (SUV) thresholds. Methods Fifteen patients with thoracic esophageal cancer sequentially underwent 3DCT, 4DCT, and FDG PET-CT of the thorax simulation. IGTVs were delineated on ten phases of 4DCT images and then combined to obtain IGTV₁₀. IGTV_PET2.0, IGTV_PET2.5, IGTV_PET3.0, IGTV_PET3.5, IGTV_PET20%, IGTV_PET25%, IGTV_PET30%, IGTV_PET35%, and IGTV_PET40% were delineated on PET images based on different SUV thresholds (≥2.0, 2.5, 3.0, and 3.5) and percentages of SUV_max(≥20%, 25%, 30%, 35%, and 40%). The volume, CI, and DI were compared between IGTVs by paired t test. The correlations of centroid distance with CI and DI were determined by Pearson correlation analysis. Results The volumes of IGTV_PET2.5 and IGTV_PET20% were similar to that of IGTV₁₀, with volume ratios of 0.92(P=0.985) and 1.08(P=0.886), respectively. The CIs of IGTV_PET2.0 vs IGTV₁₀, IGTV_PET2.5 vs IGTV₁₀, and IGTV_PET20% vs IGTV₁₀ were similar (0.53, 0.52, and 0.53;P=0.432, 1.00, and 0.414), but they were significantly higher than the CIs of other IGTV_PET vs IGTV₁₀(0.33—0.50, P=0.000—0.047). No significant differences existed between the DIs of IGTV₁₀ in IGTV_PET2.5(0.67) and IGTV₁₀ in IGTV_PET20%(0.70)(P=0.542) and between the DIs of IGTV_PET2.5 in IGTV₁₀(0.74) and IGTV_PET20% in IGTV₁₀(0.72)(P=0.539). Conclusions IGTV_PET2.5 and IGTV_PET20% have similar volumes and good spatial matching compared with IGTV₁₀.