多排螺旋CT低剂量扫描高分辨率重建在新型冠状病毒肺炎筛查中的应用

目的:探讨多排螺旋CT（MDCT）低剂量扫描高分辨率重建在新型冠状病毒肺炎（COVID-19）筛查中的应用价值。方法:选取2020年2月1日~3月1日间就诊的66例疑似COVID-19肺炎患者作为研究对象，将66例患者随机平均分为2组，分别实施胸部常规剂量CT扫描（n=33, 120 kV, 300 mAs）和胸部低剂量CT扫描（n=33，100 kV，70 mAs），其中常规剂量组采用512×512矩阵，低剂量组采用1 024×1 024矩阵。同时对胸部低剂量组用4种不同权重的迭代算法进行处理（30%、50%、70%、90%），对比两种检查模式的辐射剂量和图像质量。结果:低剂量组的有效辐射剂量为（1.81±0.14） mSV，与常规剂量组（6.83±0.68） mSV相比降低73.5%（P<0.05）；采用1 024大矩阵、90%权重迭代算法的低剂量组图像的CNR、SNR均略低于采用512常规矩阵、90%权重迭代算法的常规剂量组，但差异无统计学意义（SNR:5.11±0.75 vs 5.38±0.41，CNR:5.37±0.33 vs 5.44±0.51, P>0.05）；低剂量组患者的肺窗、纵膈窗图像质量主观评分低于常规剂量组，但差异无统计学意义（肺窗:3.30±0.72 vs 3.39±0.78；纵膈窗:3.15±0.90 vs 3.36±0.82, P>0.05）。结论:使用MDCT进行胸部低剂量扫描，同时采用高分辨率重建技术及90%权重迭代算法可用于COVID-19肺炎筛查，可在保证图像质量的前提下显著降低患者所受辐射剂量。

Application of low-dose multidetector CT scan and high-resolution reconstruction in COVID-19 pneumonia screening

Abstract: Objective To explore the application value of low-dose multidetector computed tomography (CT) scan combined with high-resolution reconstruction in the screening of COVID-19 pneumonia. Methods A total of 66 patients with suspected COVID-19 pneumonia who came to Lanzhou University Second Hospital from February 1, 2020 to March 1, 2020 were enrolled, and then randomly divided into 2 groups, namely conventional-dose CT scan group (n=33, 120 kV, 300 mAs) and low-dose CT scan group (n=33, 100 kV, 70 mAs). A 512×512 matrix was adopted in conventional-dose group, and a 1 024×1 024 matrix in low-dose group. Meanwhile, low-dose group was processed with 4 iterative algorithms with different weights (30%, 50%, 70%, 90%). The radiation dose and image quality of two groups were compared. Results The effective radiation dose of low-dose group was (1.81±0.14) mSV, which was reduced by 73.5% (P<0.05) compared with (6.83±0.68) mSV in conventional-dose group. The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) of low-dose group with a 1 024×1 024 matrix and 90% weight iterative algorithm were slightly lower than those of conventional-dose group with a 512×512 matrix and 90% weight iterative algorithm, without statistical differences (SNR: 5.11±0.75 vs 5.38±0.41, CNR: 5.37±0.33 vs 5.44±0.51, P>0.05). The subjective image quality scores of pulmonary window and mediastinal window in low-dose group were lower than those in conventional-dose group, but the differences were not statistically significant (pulmonary window: 3.30±0.72 vs 3.39±0.78 mediastinal window: 3.15±0.90 vs 3.36±0.82, P>0.05). Conclusion Multidetector CT for low-dose scan combined with high-resolution reconstruction technique and 90% weight iterative algorithm can be applied for COVID-19 pneumonia screening, which can significantly reduce the radiation dose to patients while ensuring image quality.