Revolution CT剂量匹配技术对肝脏脂肪含量测量值的影响  

To explore the effect of Revolution CT dose matching technique on the measurements of liver fat content

作　　者：王诗瑜 刘义军[1] 魏巍 李贝贝 王旭[1] 童小雨 WANG Shi-yu;LIU Yi-jun;WEI Wei(Department of Radiology,the First Affiliated Hospital of Dalian Medical University,Liaoning 116011,China)

机构地区：[1]大连医科大学附属第一医院放射科,辽宁大连116011

出　　处：《放射学实践》2024年第4期534-539,共6页Radiologic Practice

摘　　要：目的:探讨基于剂量匹配的个体化低管电流扫描对定量CT(QCT)肝脏脂肪含量测量及图像质量的影响。方法:前瞻性将2022年2月-12月在本院接受胸部及上腹部CT扫描的253例患者纳入研究。对两次扫描重叠部分的肝脏进行对照研究。胸部扫描采用个体化低剂量扫描(A组),管电压120 kVp,管电流采用Smart mA技术,通过手动调整噪声指数(NI)降低管电流,使其辐射剂量等同于基于Auto-prescription技术推荐的80 kVp或100 kVp的辐射剂量,分别记为A1组和A2组。上腹部为常规120 kVp扫描(B组),与A组对应分为B1、B2组。扫描完成后对A组图像分别采用40%、60%和80%权重后置ASIR-V进行图像重建。分别测量每组图像上胸部及上腹部扫描时肝脏重叠部位的CT值及其SD值和肝脏脂肪含量体积百分比(Fat%QCT),以同层面两侧竖脊肌作为背景组织,计算肝实质的SNR和CNR。由两位观察者分别采用5分法评估各组胸部图像的图像质量。采用配对样本t检验比较A、B组之间肝脏的Fat%QCT、CT值及其SD值、SNR和CNR及辐射剂量的差异。采用Bland-Altman分析评估胸腹部图像上测量的Fat%QCT值的一致性。两位放射科医师对图像质量主观评分的一致性及差异分别采用Kappa检验和Wilcoxon秩和检验。结果:A组内不同权重ASIR-V图像上测量的Fat%QCT值的差异无统计学意义(P>0.05);A、B组之间肝脏的CT值和Fat%QCT值的差异均无统计学意义(P>0.05);A组后置60%ASIR-V图像上肝脏的SNR和CNR高于B组,但图像质量主观评分的差异无统计学意义(P>0.05)。结论:以Auto-prescription技术推荐的辐射剂量为参考,通过剂量匹配,在常规120 kVp时通过改变管电流的方法来降低辐射剂量,对QCT肝脏脂肪含量的测量无显著影响,且不同权重后置ASIR-V对QCT肝脏脂肪含量的测量无影响。Objective:To investigate the effect of individualized low tube current based on dose matching of quantitative CT(QCT)on the measurements of liver fat content and image quality.Methods:A prospective collection of 253 patients who received chest and upper abdominal CT scans in our hospital from February to December 2022 was conducted to study the overlapping part of liver in the two scans.The chest was scanned with tube voltage of 120kVp and personalized tube current recommended by smart mA(group A).In group A,by manually modifying the noise index(NI),the tube current was reduced to achieve an equivalent radiation dose as that of 80 or 100kVp scans based on auto-prescription technique,and was denoted as group A1 and group A2 respectively.The upper abdomen was scanned with conventional tube voltage of 120kVp(group B),further divided into B1 and B2 groups corresponding to group A.After scanning,the images of group A were reconstructed by 40%,60%,and 80%posterior ASIR-V.In each set of images,the CT value,SD value and volume percentage of liver fat content(Fat%QCT)in the overlapping parts of chest and upper abdomen were measured.The liver SNR and CNR were calculated against the background of erector spinae muscles on both sides at the same slice.The quality of chest images was assessed by two observers using a five-point scale.Paired sample t-test was used to compare the differences of Fat%QCT,CT value,SD,SNR,CNR and radiation dose between groups A and B.Bland-Altman analysis was applied to evaluate the consistency of Fat%QCT measured between chest and upper abdomen images.The consistency and the differences of the subjective scores among two radiologists were examined by Kappa test and Wilcoxon sign rank test,respectively.Results:There was no statistically significant difference of Fat%QCT mea-sured with different ASIR-V weights in group A(P>0.05).There was no statistically significant difference in the CT value and Fat%QCT between group A and B(P>0.05).The liver SNR and CNR on the images using posterior 60%ASIR-V in

关 键 词：肝脏疾病 脂肪含量 定量CT 剂量匹配 辐射剂量 图像质量 

分 类 号：R814.42[医药卫生—影像医学与核医学] R575.5[医药卫生—放射医学]