新型冠狀病毒肺炎的影像學表現

[TinyNotes]

作者：台大醫院 沈嘉浤醫師

前言
新型冠狀病毒肺炎(COVID-19)於近幾個月造成全球的大流行，目前被台灣疾病管制署歸類為第五類法定傳染病，相關教材可參考疾管署所提供的教材。

臨床症狀

• 常見的症狀包括發燒、疲勞、乾咳等。
• 近幾日台灣疾管署也將嗅/味覺喪失以及不明原因腹瀉列入通報條件中。

實驗室診斷學

• 淋巴球減少 (Lymphopenia)(70%)
• PT延長 (prolonged prothrombin time)(約60%)
• LDH升高 (elevated lactate dehydrogenase)(40%)

影像學表現

• 新型冠狀病毒肺炎患者的胸部X光可能出現不規則性的肺部陰影，

• 但胸部X光在輕症或者疾病早期可能沒有特異性的變化。

• 第一線診斷以RT-PCR為主，電腦斷層比胸部X光有較高特異性。

胸部X光

• 簡介

  • 新型冠狀病毒肺炎病人只有70%在病程初期胸部X光可見不正常變化，
  • 10%的病人初期胸部X光為正常，隨著病情進展出現異常變化。
  • 胸部X光變化最明顯的時間點為病程中從有症狀算起第10-12天時。

• 常見表現

  • 肺部實質化變化Consolidation (47%)
  • 分布區域:
    雙側bilateral involvement (50%)，周邊peripheral (41%)，下側肺野較常見(50%)。

• 少見變化

  • 較少見Perihilar predominant Consolidation (10%),
  • 極少見肋膜積水Pleural effusion(3%)，如出現需考慮其他肺炎可能性。

• (A) multifocal patchy consolidations, bilateral, lower part為主. COVID-19典型變化。
• (B) pleural effusion, left. COVID-19極少見。
• (C) focal consolidations, right, perihilar distribution, COVID-19較少見。
• (D) ill-defined consolidations, bilateral, peripheral distribution. COVID-19典型變化。
• 注意!! AD為典型表現，BC較少見，見到需考慮其他種類肺炎可能性。

(Image: Ho Yuen Frank Wong et al. Frequency and Distribution of Chest Radiographic Findings in COVID-19 Positive Patients. Radiology.)

胸部電腦斷層

• 在胸部電腦斷層的檢查中，可能有三種較常見的表現，分別為

  • 雙側周邊為主的毛玻璃狀病變 (約90%) (Bilateral Ground-Glass Opacity of Peripheral Distribution with or without Central Distribution)

  • 肺部血管增厚 (約35%)(Vascular Thickening)

  • 網狀陰影變化 (約55%)(Fine Reticular Opacity)

Bilateral Ground-Glass Opacity of Peripheral Distribution，COVID-19典型變化。
(Image: Adam Bernheim et al. Chest CT Findings in Coronavirus Disease-19 (COVID-19): Relationship to Duration of Infection. Radiology 2020)

Ground-glass opacities with vascular enlargement，COVID-19典型變化。
(Image: Yan Li and Liming Xia, Coronavirus Disease 2019 (COVID-19): Role of Chest CT in Diagnosis and Management. American Journal of Roentgenology: 1-7. 10.2214/AJR.20.22954)

Bilateral subpleural crescent-shaped ground-glass opacities in both lungs, as well as posterior reticular opacities and subpleural crescent-shaped consolidations.
(Image: Heshui Shi et al. Radiological findings from 81 patients with COVID-19
pneumonia in Wuhan, China: a descriptive study. Lancet Infect Dis 2020;
20: 425–34.)

• 如果出現以下三種較少見表現需考慮其他肺炎可能性:
  (1) 淋巴結腫大(3%)Lymphadenopathy
  (2) 肋膜積水(4%)Pleural effusion
  (3) 胸膜增厚(15%)Pleural thickening

• 在一部分的病人中，可能出現雖然聚合酶連鎖反應測試(RT-PCR)為陰性，但在電腦斷層上卻有早期典型的新型冠狀病毒肺炎肺部實質變化的情況。

總結 (Summary conclusion)

懷疑新型冠狀病毒肺炎的患者診斷上注意事項

• 症狀: 發燒、疲勞、乾咳、味嗅覺喪失、不明原因腹瀉

• 抽血:可能出現Lymphopenia

• 影像學-CXR
  Consolidation, bilateral, peripheral and lower predominant

• 影像學-Chest CT

  • 雙側周邊為主的毛玻璃狀病變 (Bilateral Ground-Glass Opacity of Peripheral Distribution with or without Central Distribution)
  • 肺部血管增厚(Vascular Thickening)
  • 網狀陰影變化 (Fine Reticular Opacity)

文獻引用

• 你所不知道的影像醫學(中華民國放射線醫學會衛教專區) [https://www.facebook.com/TaiwanRadiology/photos/a.406560230118581/651277772313491/]
• 台灣CDC,第五類法定傳染病,嚴重特殊傳染性肺炎,[https://www.cdc.gov.tw/Category/MPage/V6Xe4EItDW3NdGTgC5PtKA].
• Weifang Kong, Chest Imaging Appearance of COVID-19 Infection; Radiology: Cardiothoracic Imaging 2020.
• Peikai Huang, Tianzhu Liu, Use of Chest CT in Combination with Negative RT-PCR Assay for the 2019 Novel Coronavirus but High Clinical Suspicion; Radiology 2020.
• Wang D et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA. 2020.
• Ho Yuen Frank Wong et al. Frequency and Distribution of Chest Radiographic Findings in COVID-19 Positive Patients. Radiology.
• Heshui Shi et al. Radiological findings from 81 patients with COVID-19
  pneumonia in Wuhan, China: a descriptive study. Lancet Infect Dis 2020;
  20: 425–34.
• Bai HX et al. Performance of radiologists in differentiating COVID-19 from viral pneumonia on chest CT. Radiology. 2020 Mar.
• Adam Bernheim et al. Chest CT Findings in Coronavirus Disease-19 (COVID-19): Relationship to Duration of Infection. Radiology 2020.
• Tao Ai et al. Correlation of Chest CT and RT-PCR Testing in Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases. Radiology 2020.
• Yan Li and Liming Xia, Coronavirus Disease 2019 (COVID-19): Role of Chest CT in Diagnosis and Management. American Journal of Roentgenology: 1-7. 10.2214/AJR.20.22954.