噪声指数结合多模型自适应迭代重建在学龄前儿童上腹部CT扫描中的应用价值

Exploration of noise index combined with ASIR-V in CT scanning of pre-school children's upper abdomen

目的:探讨噪声指数结合多模型自适应迭代重建(ASIR-V)在学龄前儿童上腹部低剂量CT扫描中的应用价值,探寻适合学龄前儿童上腹部CT的最佳扫描方案。方法:连续选取在我院行上腹部CT检查的学龄前儿童50例,按噪声指数(NI)值不同随机分为5组(NI值分别设为9、11、13、15、17),每组10例。CT检查采用GE Revolution CT机,管电压100 kV,管电流50~350 mA,所有图像均行ASIR-V(权重分别为0%、20%、40%、60%、80%、100%,共6个亚组)。采用单因素方差分析比较不同NI和ASIR-V权重条件下图像CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)、标准差(SD)、信噪比(SNR)、对比信噪比(CNR)等客观指标,采用Kruskal-Wallis H检验比较图像主观评分。结果:随着NI值的增大,图像的SD、CNR、CTDIvol、DLP等逐渐降低,NI=15、17组的滤波反投影(FBP)重建图像评分低于3分;随着ASIR-V权重的增大,图像的SD、CNR等值逐渐升高,权重为40%和60%的图像显示效果最佳。NI=15且ASIR-V为40%、60%图像的主观评分大于3分,CTDIvol和DLP较NI=9组分别下降了约55.5%和54.4%。结论:学龄前儿童上腹部CT平扫采用低管电压100 kV结合NI=15及ASIR-V40%的扫描方案,可以在明显降低辐射剂量的同时获取不影响临床诊断的图像。

Objective:To explore the application of noise index combined with adaptive statistical iterative reconstruction Veo(ASIR-V)in low-dose CT scanning of upper abdomen of pre-school children.Methods:Fifty children with upper abdominal CT scanning in our hospital were enrolled and randomly divided into 5 groups according to NI=9~17(interval 2)with 10 children in each group.The tube voltage was 100kV and the tube current was 50~350 mA.All images were reconstructed with ASIR-V(0%~100%,interva 20%).The CTDIvol,DLP,SD,SNR,CNR and other indicators were analyzed and compared using one way ANOVA under the different conditions of NI and ASIR-V.And the subjective scores were compared by Kruskal-Wallis H test.Results:With the increase of NI level,the SD,CNR,CTDIvoland DLP decreased gradually,and the scores of FBP reconstructed images in NI=15 and 17 groups were lower than 3 points.With the increase of ASIR-V,the SD and CNR values gradually increased,and the images with ASIR-V 40%~60%were the best.The image of NI=15 with 40%~60%of ASIR-V scores were higher than 3 points,in comparison with NI=9 group,CTDIvol and DLP decreased by 55.5%and 54.4%,respectively.Conclusions:The low tube voltage 100kV combined with NI=15 and ASIR-V 40%used in upper abdomen CT scan of preschool children can significantly reduce the radiation dose and obtain the images without affecting the clinical diagnosis.