2020-04-26 09:43:27
据AuntMinnie.com报道, 2020年4月21日发表于Radiology: Cardiothoracic Imaging 一篇论文发现[1]，剂量在1mSv以下（亚mSv）的胸部CT可以准确快速地评估急诊室患者的COVID-19感染情况，特别是那些出现症状超过48小时的病人。这能够帮助临床医生快速诊断病人，同时避免不必要的辐射。鉴于目前胸部CT在COVID-19检测中应用广泛，亚mSv胸部CT照射剂量小（比Tao等人[2] 使用的CT减少到1/5），使用亚mSv胸部CT可以大幅度减少人群接受剂量。
Dangis团队指出，实时聚合酶链反应（RT-PCR）测试是现在诊断COVID-19的黄金标准，但是它的灵敏度可低至70%。而一些研究证明，胸部CT的灵敏度可超过90%，提供了诊断新冠肺炎的另一种工具。
为了确定剂量大小和诊断CT所需时间，Dangis的团队对192名具有COVID-19症状的急诊室患者进行研究。这些患者在3月14至24日期间接受了亚mSv胸部CT照射以及RT-PCR测试，CT照射参数为100kVp、20mAs、螺距1.2，治疗床旋转0.5秒。在192名病人中，43.2%的人COVID-19检测呈阳性，其余56.8%的人检测呈阴性。病人的平均年龄是62岁，但患有COVID-19的人平均年龄（67岁）高于不患病的人（57岁），并且有更大概率出现发热（68.7%和45.9%）。
小组发现亚mSv胸部CT在各种测量数据中表现良好，特别是对出现症状超过48小时的病例（图1、表1）。亚mSv胸部CT的平均有效剂量是0.56mSv。获取CT图像和患者报告的中位时间是25分钟（13-49分钟）。CT测试中观察者内相关系数和观察者间相关系数分别是0.96和0.95，没有明显偏差。
图1 两个患有COVID-19的病例的CT图像。图A和图B是一位呼吸困难、发烧的85岁女士的轴向（A）和冠向（B）CT图像。CT图像显示了典型的早期COVID-19症状，双侧胸膜下出现磨玻璃影（箭头所示）。有效剂量是0.52mSv。图C和图D是一位咳嗽、发烧14天的41岁女士的轴向（C）和冠向（D）CT图像。CT图像显示了典型的COVID-19晚期症状，双侧胸膜下出现多灶性实变（箭头所示）。有效剂量是0.53mSv。上述图片和标题由北美放射学会（Radiological Society of North America, RSNA）提供。
因此Dangis总结认为，对可能感染COVID-19的患者进行早期诊断分类时，低剂量亚mSv胸部CT可以作为RT-PCR重要的补充手段
[1] Anthony Dangis, Christopher Gieraerts, Yves De Bruecker, Lode Janssen, Hanne Valgaeren, Dagmar Obbels, Marc Gillis, Marc Van Ranst, Johan Frans, Annick Demeyere, Rolf Symons. Accuracy and reproducibility of low-dose submillisievert chest CT for the diagnosis of COVID-19. Radiology. Vol.2. No. 2 (Apr 21 2020) https://doi.org/10.1148/ryct.2020200196.
[2] Ai, T., Yang, Z., Hou, H., Zhan, C., Chen, C., Lv, W., ... & Xia, L. (2020). Correlation of Chest CT and RT-PCR Testing in Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 C
以下为原文：
Low-dose CT works well for COVID-19 assessment
Chest CT at a radiation dose under 1 mSv can accurately and rapidly assess COVID-19 infection in emergency room patients -- particularly those who have had symptoms longer than 48 hours, according to a study published April 21 in Radiology: Cardiothoracic Imaging by Dangis et al [1].
The results are good news for clinicians seeking to diagnose patients quickly while also avoiding undue radiation exposure, wrote a team led by Dr. Anthony Dangis of Imelda Hospital in Bonheiden, Belgium.
"[We found] an estimated radiation dose reduction by a factor of five," the group wrote. "Given the widespread use of chest CT for COVID-19 detection, our results demonstrate the feasibility of using low-dose chest CT to achieve an important reduction in radiation dose on a population level during this pandemic."
Real time polymerase chain reaction (RT-PCR) testing is currently the gold standard for diagnosing COVID-19, but its sensitivity can be as low as 70%, the group noted. Chest CT offers an additional diagnostic tool for the disease, with a sensitivity of more than 90%, according to some studies.
