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目的:比较n 18F-脱氧葡萄糖(FDG)PET/CT的4种重建算法对肺结节标准摄取值(SUV)的影响。n 方法:回顾性收集2018年2月至2019年7月在山西医科大学第一医院行n 18F-FDG PET/CT检查的46例实性肺结节患者[男27例，女19例，中位年龄66(44～82)岁]的PET/CT图像，采用有序子集最大期望值迭代法(OSEM)、OSEM＋飞行时间(TOF)、OSEM＋TOF＋点扩散函数(PSF)及正则化算法(BSREM)进行图像重建(方法依次以G1～G4表示)，通过视觉和半定量方法分析肺结节及背景参数。根据肺窗所测结节直径，分为小结节(直径≤10 mm)和大结节(10 mm<直径≤30 mm)。行Kruskal-Wallis秩和检验及Bonferroni法分析不同算法间SUV的差异，行Spearman相关分析探讨SUV变化率(%ΔSUV)与结节直径的相关性，行受试者工作特征(ROC)曲线分析探讨SUV对肺结节良恶性的诊断效能。n 结果:共114个结节，大结节55个，小结节59个。在视觉分析中，G4较G1～G3的小结节视觉检出率分别提高了55.93%(33/59)、44.07%(26/59)和20.34%(12/59)。在114个肺结节中，最大SUV(SUVn max)、平均SUV(SUVn mean)在不同算法间比较差异有统计学意义(中位SUVn max ：2.65～5.29，中位SUVn mean：2.05～2.99；n H值：20.628和17.749，均n P<0.001)，G4对G1的SUVn max(中位数分别为5.29和2.65)和SUVn mean(中位数分别为2.99和2.05)有明显提升(均n P<0.001)。%ΔSUVn max(中位数：4.45%～52.96%)、%ΔSUVn mean(中位数：1.69%～47.56%)与结节直径呈负相关[9.75(6.20，16.58) mm；n rn s值：－0.371～－0.354、－0.371～－0.320，均n P<0.001]。在59个小结节中，G4对G1的SUVn max(中位数分别为4.05和2.14)有明显提升(n H＝18.327, n P<0.001)，G4对G1和G3的SUVn mean (中位数分别为2.31、1.26和1.53)有提升作用(n H＝16.808，均n P0.05)。G1～G4的SUVn max诊断良恶性的最佳截断值分别为4.335、5.185、5.410、5.745，曲线下面积(AUC)分别为0.747、0.699、0.756和0.778，四者的SUVn mean及SUVn peak最佳截断值对应的AUC也显示出类似趋势。n 结论:在4种重建算法中，BSREM可明显提高图像质量和直径10 mm以下肺结节的SUVn max及SUVn mean，其SUV良恶性诊断阈值应适当上调。n “,”Objective:To compare four reconstruction algorithms of n 18F-fluorodeoxyglucose (FDG) PET/CT on standardized uptake value (SUV) of pulmonary nodules.n Methods:A total of 46 patients (27 males, 19 females; median age: 66 (range: 44-82) years) with solid pulmonary nodules from February 2018 to July 2019 in the First Hospital of Shanxi Medical University who performed n 18F-FDG PET/CT imaging were enrolled. All PET/CT images were retrospectively reconstructed by using four algorithms reconstructions including ordered subset expectation maximization (OSEM), OSEM+ time of flight (TOF), OSEM+ TOF+ point spread function (PSF) and block sequential regularized expectation maximization (BSREM) (G1-G4). Nodule and background parameters were analyzed semi-quantitatively and visually. The maximum of SUV(SUVn max), mean of SUV(SUVn mean) and peak of SUV (SUVn peak) were collected by the region of interest (ROI). Nodules were divided into small nodule group (diameter ≤10 mm) and large nodule group (10 mm < diameter ≤30 mm). Kruskal-Wallis rank sum test and Bonferroni method were performed to compare the differences of SUVs between G1-G4, and Spearman correlation analysis was used to analyze the correlation between the change rate of SUV (%ΔSUV) and the diameter of nodules. The receiver operating characteristic (ROC) curve analysis was used to analyze the diagnostic efficacy of SUV for the differential diagnosis of pulmonary nodules and to get the optimal threshold.n Results:There were 114 pulmonary nodules (large nodules, n n=55; small nodules, n n=59). In visual analysis, the visual detection rates of small nodules in G4 were 55.93%(33/59), 44.07%(26/59), 20.34%(12/59) higher than those in G1-G3. Of 114 pulmonary nodules in 46 patients, there were differences in SUVn max and SUVn mean between G1-G4 (median SUVn max : 2.65-5.29, median SUVn mean: 2.05-2.99; n H values: 20.628 and 17.749, respectively, both n P<0.001), G4 had significant increases compared to G1 in SUVn max (median 5.29 and 2.65, n P<0.001) and SUVn mean (median 2.99 and 2.05, n P<0.001). The %ΔSUVn max (median: 4.45%-52.96%) and %ΔSUVn mean (median: 1.69%-47.56%) were negatively correlated with the diameter of nodules (9.75(6.20, 16.58) mm; n rn s values: -0.371 to -0.354, -0.371 to -0.320, all n P<0.001). In 59 small nodules, G1 significantly increased the SUVn max of G4 (median 4.05 and 2.14, n H=18.327, n P<0.001), while G4 significantly increased the SUVn mean of G1 and G3 (median 2.31, 1.26 and 1.53, n H=16.808, n P0.05). The optimal threshold values of SUVn max in G1-G4 were 4.335, 5.185, 5.410, 5.745 and the area of under curves (AUCs) were 0.747, 0.699, 0.756, 0.778 respectively. The AUC of SUVn mean and SUVn peak also showed a similar trend.n Conclusion:Among the four reconstruction algorithms, BRERM can not only enhance the image quality, but also significantly improve the SUVn max and SUVn mean of lung nodules diameter below 10 mm, and thus its diagnostic threshold of SUV should be appropriately increased.n