高清晰CT胸部低剂量筛查的临床应用

Clinical application of the low-dose chest screening with high definition CT

目的观察应用高清晰CT(HDCT)制订肺部低剂量筛查的扫描方案及可行性。方法将150名胸部体检者随机分为三组(试验组1、试验组2及对照组),应用HDCT,采用自动毫安调节技术行胸部CT扫描。试验组1、试验组2及对照组预设噪声指数(NI)分别为22HU、30HU及15HU,设置ASIR值分别为50%、50%和30%。记录三组的CT剂量指数(CTDIvol)、剂量长度乘积(DLP)并估算有效剂量(ED)。采用5分制对图像质量进行评估,并用Kappa检验评价观察者间的一致性。结果试验组1的CTDIvol为(3.00±1.41)mGy,试验组2为(1.48±0.53)mGy,对照组为(5.51±2.21)mGy。试验组1、试验组2的CTDIvol较对照组分别减少了45.55%和73.14%,DLP和ED分别减少了48.58%和73.72%。试验组2的ED降低至(0.71±0.28)mSv。三组图像的的质量均满足临床诊断要求,观察者间的评估具有一致性。结论采用HDCT,可以在获得稳定图像质量的前提下实现更低剂量的胸部CT筛查。

Objective To evaluate the program and the feasibility of low dose chest CT screening with high definition CT （HDCT）. Methods Totally 150 subjects underwent chest screening using GE Discovery CT750 HD with automatic tube current （mA） modulation. All the subjects were devided randomly into three groups,including study group 1,2 and the control group. The noise index （NI） for the study group 1,2 and the control group was set to 22 HU,30 HU and 15 HU,respectively. The adaptive statistical interative reconstruction （ASIR） for each group was set to 50%,50% and 30%,respectively. CT dose index volumes （CTDIvol） and dose length product （DLP） were recorded,while effective dose （ED） was estimated. Image quality was assessed by two radiologists on a 5-point scale. The degree of inter-observers concordance was evaluated with Kappa statistics. Results The average CTDIvol for study group 1,2 and the control group was （3.00±1.41）mGy,（1.48±0.53）mGy and （5.51±2.21）mGy,respectively. Compared to that of the control group,the average CTDIvol decreased in the study group 1 and the study group 2 was 45.55% and 73.14%,while DLP and ED decreased in these two study groups （48.58% and 73.72%）. The ED in study group 2 decreased to （0.71±0.28）mSv. The images of each group had acceptable image quality,and there was inter-observers agreement in diagnosis acceptability. Conclusion HDCT can be used to obtain consistent image quality with remarkable radiation dose reduction.