前置体型特异性剂量估算值优化CT冠状动脉成像的可行性

Feasibility of pre-scan size-specific dose estimate in coronary computed tomography angiography

目的探讨前置体型特异性剂量估算值(SSDE)优化CT冠状动脉成像(CCTA)的可行性。方法回顾性分析2018年3月至2018年5月衢州市人民医院90例行CCTA扫描的患者资料,建立水等效直径(dw)与体质量指数(BMI)的回归方程,并计算容积CT剂量指数(CTDIvol)上四分位数。前瞻性收集2018年12月至2019年1月衢州市人民医院行CCTA扫描患者67例,按随机数表法分为对照组(32例)和试验组(35例)。对照组使用固定CTDIvol设定扫描方案,试验组使用固定SSDE设定扫描方案。两组的目标剂量为90例患者CTDIvol的上四分位数。评估并比较两组图像质量及辐射剂量。结果90例患者BMI与dw正相关(r=0.823,P<0.05),回归方程为dw=9.241+0.644×BMI;CTDIvol的上四分位数为7.92 mGy。对照组和试验组冠状动脉血管段图像质量的优良率分别为94.10%(367/390)和93.93%(402/428),差异无统计学意义(P>0.05);对照组和试验组SNR和CNR的中位数分别为21.08、24.39和17.24、19.94,差异无统计学意义(P>0.05)。试验组的CTDIvol、SSDE和女性乳腺辐射剂量(Dbre)分别较对照组降低37.04%、35.77%和37.37%,差异均具有统计学意义(z=-7.041,t=18.479,15.079,P<0.05)。结论基于前置SSDE设定CCTA方案具有可行性,保证图像质量的同时,可有效降低辐射剂量。

Objective To investigate the feasibility of optimization of coronary computed tomography angiography(CCTA)with pre-scan size-specific dose estimate(SSDE).Methods Ninety patients from Quzhou People′s Hospital during March and May 2018 who underwent CCTA were defined as modelled patients,the regression equation of body mass index(BMI)and water-equivalent diameter(dw)were conducted and upper quartile of CTDIvol values was calculated.Other 67 patients were divided into two groups:control group(CCTA scan protocol,based on CTDIvol)and study group(CCTA scan protocol using SSDE).The image quality and radiation dose including breast dose(Dosebre)in two groups were assessed.Results The positive correlation was found between BMI and dw with a linear regression equation of dw=9.241+0.644×BMI(r=0.823,P<0.05),and the upper quartile of CTDIvol was 7.92 mGy.The proportions of high-level image quality were 94.10%(367/390)and 93.93%(402/428)in the control and study groups,respectively(P>0.05).The median signal to noise ratio(SNR)and contrast to noise ratio(CNR)were 21.08/24.39,17.24/19.94 in the control and study groups,respectively(P>0.05).The CTDIvol,SSDE and Dbreof the study group were reduced by 37.04%,35.77%and 37.37%compared with the control group,and statistically significant differences were found(z=-7.041,t=18.479,15.079,P<0.05)among them.Conclusions The CCTA scan protocol based on the pre-scan SSDE can significantly reduce the radiation dose and provide the diagnostic image quality.