双源双能量CT成像在新型冠状病毒肺炎中的应用价值

目的探讨双源双能量计算机体层成像（CT）不同单能量重建对新型冠状病毒肺炎（COVID-19）间质性病灶的显示和图像质量及辐射剂量的影响。 方法回顾性分析2020年1—3月郑州大学第一附属医院收治的20例COVID-19患者的胸部平扫影像学资料。比较同一患者双源双能量CT与常规CT的扫描辐射剂量。同时重建双源双能量CT扫描40、60、80、100、120 keV单能量图像，比较不同单能量图像间质性病灶的CT值和标准差（SD），计算信噪比（SNR）和对比噪声比（CNR）；由2名经验丰富的肺部诊断医师采用5分法评估不同单能量图像质量，并进行比较。 结果双源双能量CT组的CT容积剂量指数（CTDI_vol）为（6.0±2.4）mGy，较常规CT组的（8.9±2.9）mGy下降了33%，且差异有统计学意义（t=10.694，P<0.001）；双源双能量CT组剂量长度乘积（DLP）和全身有效剂量（ED）分别为（217.5±79.6）mGy·cm和（3.1±1.1）mSv，低于常规CT组的（333.8±109.0）mGy·cm（t=10.727，P<0.001）和（4.67±1.52）mSv（t=10.730，P<0.001）。随着X线能量的升高，单能量图像的SNR和CNR逐渐增加，CT值和SD值逐渐降低，相邻两组间比较差异均有统计学意义（P<0.001）。2名诊断医师的图像质量主观评价一致性较好（Kappa值为0.700~0.857，P<0.001），不同单能量图像主观评分差异均有统计学意义（P<0.001），其中80 keV图像主观评分最高。 结论与常规CT相比，使用双源双能量CT降低了辐射剂量；120 keV单能量图像质量客观评价较高，但80 keV单能量图像更有利于间质性病灶的显示，对提示病情进展具有重要意义。

Application value of dual-source dual-energy computed tomography in 2019 novel coronavirus pneumonia

ObjectiveTo investigate the effects of dual-source dual-energy computed tomography (CT) scanning with different single-energy reconstructions on the display of interstitial lesions of 2019 novel coronavirus pneumonia (COVID-19), image quality and radiation dose. MethodsThe chest plain scan imaging data of 20 patients with COVID-19 from January to March 2020 in the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. The radiation dose of dual-source dual-energy CT and conventional CT were compared in the same patient, and the single energy images of 40 keV, 60 keV, 80 keV, 100 keV and 120 keV of dual-source dual-energy CT were compared. The CT value and standard deviation (SD) of interstitial lesions with different energy were compared, and signal-noise ratio (SNR) and contrast-noise ratio (CNR) were calculated. The image quality was assessed by two experienced pulmonary diagnostician using the 5-point method, and the differences in image quality among different single-energy groups were compared. ResultsCT dose index (CTDI_vol) in the dual-source dual-energy CT group was (6.0±2.4) mGy, which decreased by 33% compared with the conventional CT group (8.9±2.9) mGy, with a statistically significant difference (t=10.694, P<0.001). dose length product (DLP) and effective dose (ED) in the dual-source dual-energy CT group were (217.5±79.6) mGy·cm and (3.1±1.1) mSv respectively, which were significantly lower than those in the conventional CT group (333.8±109.0) mGy·cm (t=10.727, P<0.001) and (4.7±1.5) mSv (t=10.730, P<0.001). In the reconstructed images of the 5 groups, with the increase of X-ray energy, the SNR and CNR of the single energy group gradually increased, while the CT value and SD value of the images gradually decreased, and there were statistically significant differences between the two adjacent groups (P<0.001). The consistency of the subjective evaluation of the image quality of the two diagnostic physicians was good (Kappa value was between 0.700 and 0.857, P<0.001). There were statistically significant differences in subjective scores of different energy images (P<0.001), and the subjective score of image in the 80 keV group was the highest. ConclusionsCompared with the conventional CT, the use of dual-source dual-energy CT reduces the radiation dose. The quality score of 120 keV single-energy image is higher, but the 80 keV single-energy image is more conducive to displaying interstitial lesions, which is of great significance for indicating the progression of disease.