第三代双源CT低剂量扫描在新型冠状病毒肺炎筛查中的应用

Application of chest low-dose CT screening of Corona Virus Disease 2019 with a third-generation dual-source scanner

目的探讨第3代双源CT低剂量扫描模式结合迭代重建技术在新型冠状病毒肺炎筛查中的应用价值,并评价其辐射剂量。方法回顾分析2019年12月至2020年2月在华中科技大学同济医学院进行新型冠状病毒肺炎筛查患者120例,按随机数表法分成试验组和常规组,各60例。试验组采用第3代双源CT机,Turbo Flash扫描模式,开启CARE kV,参考管电压90 kV,螺距2.0,ADMIRE算法。常规组采用128排CT机,常规螺旋扫描模式,固定管电压120 kV,螺距1.2,FBP算法。比较两组图像中主动脉、脊柱后方肌肉及皮下脂肪CT值、主动脉噪声、信噪比(SNR)、对比噪声比(CNR),通过这些客观参数来评价图像质量,由2位高年资影像专家采用双盲法对图像质量进行主观评分,并比较两组图像的CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)及有效剂量(E)。结果试验组患者主动脉、脊柱后方肌肉的CT值分别为(45.38±4.77)和(53.41±8.44)HU,主动脉SNR为2.82±0.59,明显高于常规组的(39.68±6.26)、(42.66±6.32)HU和2.58±0.61(t=5.608、7.897、2.162,P<0.05),而主动脉噪声、CNR及主观评分差异均无统计学意义(P>0.05)。试验组患者CTDIvol、DLP、E分别为(3.09±1.02)mGy、(107.57±32.81)mGy·cm、(1.51±0.46)mSv,常规组分别为(7.00±1.80)mGy、(261.65±73.93)mGy·cm、(3.66±1.03)mSv,试验组明显低于常规组(t=-14.680、-14.756、-14.756,P<0.05)。结论在新型冠状病毒肺炎的筛查中,使用第3代双源CT低剂量扫描模式结合迭代重建技术,在获得满足临床需求图像的同时,不仅有效地降低了辐射剂量,还提高了图像的SNR。

Objective To investigate the application value of third-generation dual-source CT(3-G DSCT)low-dose scan mode combined with iterative reconstruction technology in the screening of COVID-19 and to evaluate the radiation dose.Methods One hundred and twenty patients suspected of COVID-19 from December 2019 to February 2020 were retrospectively analysed and randomly divided into two groups(test group and conventional group,60 patients in each).The parameters for test group included 3-G DSCT,Turbo Flash scan mode,CARE kV,with reference 90 kV,pitch 2.0,and ADMIRE algorithm,while those parameters for conventional group included the 128-slice CT,conventional spiral scan mode,120 kV,pitch 1.2,and FBP algorithm.The CT values of aorta,spinal posterior muscle,and subcutaneous fat,the aortic noise,signal-to-noise ratio(SNR),and contrast noise ratio(CNR)were compared to evaluate the image quality between two groups.Two experienced doctors scored the image quality using a double-blind method,and compared the CT dose index volume(CTDIvol),dose-length product(DLP),and effective dose(E)of the two groups.Results The CT value of the aorta and spinal posterior muscle and the aortic SNR in the test group were(45.38±4.77),(53.41±8.44)HU,and 2.82±0.59,and significantly higher than those in the conventional group[(39.68±6.26),(42.66±6.32)HU,2.58±0.61,t=5.608,7.897,2.162,P<0.05].The aortic noise,CNR and subjective scores between the two groups had no significant difference(P>0.05).The CTDIvol,DLP,and E in the test group were(3.09±1.02)mGy,(107.57±32.81)mGy·cm,(1.51±0.46)mSv,significantly lower than those in the conventional group[(7.00±1.80)mGy,(261.65±73.93)mGy·cm,(3.66±1.03)mSv;t=-14.680,-14.756,-14.756,P<0.05].Conclusion In the screening of COVID-19,using low-dose scanning mode of 3-G DSCT combined with iterative reconstruction technology would provide diagnostic quality images and meanwhile effectively reduce the radiation dose and improve the SNR of the image.