Coronavirus

Intensive care medicine

2019-20 coronavirus outbreak

Betacoronavirus

Virology

Abnormality

Psychiatry

Radiological weapon

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

Outbreak

Coronavirus disease 2019 (COVID-19)

Radiology

Infectious disease (medical specialty)

Coronavirus Infections

Medicine

Radiography

Pandemic

Disease

Pathology

Clinical Imaging

•COVID-19 lung infection commonly produces ground glass and consolidative opacities with a bilateral, peripheral, and lower lung distribution.•Portable CXR will likely be the primary imaging modality used in diagnosis and management of COVID-19 patients.•With high clinical suspicion for COVID-19 infection, positive CXR findings can obviate the need for CT scanning.•Lung opacities can rapidly evolve into a diffuse pattern within weeks after symptom onset, often peaking at around 6-12 days. As the global pandemic of coronavirus disease-19 (COVID-19) progresses, many physicians in a wide variety of specialties continue to play pivotal roles in diagnosis and management. In radiology, much of the literature to date has focused on chest CT manifestations of COVID-19 (Zhou et al. [[1]Zhou S. Wang Y. Zhu T. Xia L. CT features of coronavirus disease 2019 (COVID-19) pneumonia in 62 patients in Wuhan, China.Am J Roentgenol. 2020; (March): 1-8Crossref PubMed Scopus (434) Google Scholar]; Chung et al. [[2]Chung M. Bernheim A. Mei X. et al.CT imaging features of 2019 novel coronavirus (2019-nCoV).Radiology. February 2020; 200230https://doi.org/10.1148/radiol.2020200230Crossref Scopus (1764) Google Scholar]). However, due to infection control issues related to patient transport to CT suites, the inefficiencies introduced in CT room decontamination, and lack of CT availability in parts of the world, portable chest radiography (CXR) will likely be the most commonly utilized modality for identification and follow up of lung abnormalities. In fact, the American College of Radiology (ACR) notes that CT decontamination required after scanning COVID-19 patients may disrupt radiological service availability and suggests that portable chest radiography may be considered to minimize the risk of cross-infection (American College of Radiology [[3]ACR recommendations for the use of chest radiography and computed tomography (CT) for suspected COVID-19 infection|American College of Radiology. https://www.acr.org/Advocacy-and-Economics/ACR-Position-Statements/Recommendations-for-Chest-Radiography-and-CT-for-Suspected-COVID19-Infection. Accessed March 22, 2020. Google Scholar 2020.Google Scholar]). Furthermore, in cases of high clinical suspicion for COVID-19, a positive CXR may obviate the need for CT. Additionally, CXR utilization for early disease detection may also play a vital role in areas around the world with limited access to reliable real-time reverse transcription polymerase chain reaction (RT-PCR) COVID testing.The purpose of this pictorial review article is to describe the most common manifestations and patterns of lung abnormality on CXR in COVID-19 in order to equip the medical community in its efforts to combat this pandemic. As the global pandemic of coronavirus disease-19 (COVID-19) progresses, many physicians in a wide variety of specialties continue to play pivotal roles in diagnosis and management. In radiology, much of the literature to date has focused on chest CT manifestations of COVID-19 (Zhou et al. [[1]Zhou S. Wang Y. Zhu T. Xia L. CT features of coronavirus disease 2019 (COVID-19) pneumonia in 62 patients in Wuhan, China.Am J Roentgenol. 2020; (March): 1-8Crossref PubMed Scopus (434) Google Scholar]; Chung et al. [[2]Chung M. Bernheim A. Mei X. et al.CT imaging features of 2019 novel coronavirus (2019-nCoV).Radiology. February 2020; 200230https://doi.org/10.1148/radiol.2020200230Crossref Scopus (1764) Google Scholar]). However, due to infection control issues related to patient transport to CT suites, the inefficiencies introduced in CT room decontamination, and lack of CT availability in parts of the world, portable chest radiography (CXR) will likely be the most commonly utilized modality for identification and follow up of lung abnormalities. In fact, the American College of Radiology (ACR) notes that CT decontamination required after scanning COVID-19 patients may disrupt radiological service availability and suggests that portable chest radiography may be considered to minimize the risk of cross-infection (American College of Radiology [[3]ACR recommendations for the use of chest radiography and computed tomography (CT) for suspected COVID-19 infection|American College of Radiology. https://www.acr.org/Advocacy-and-Economics/ACR-Position-Statements/Recommendations-for-Chest-Radiography-and-CT-for-Suspected-COVID19-Infection. Accessed March 22, 2020. Google Scholar 2020.Google Scholar]). Furthermore, in cases of high clinical suspicion for COVID-19, a positive CXR may obviate the need for CT. Additionally, CXR utilization for early disease detection may also play a vital role in areas around the world with limited access to reliable real-time reverse transcription polymerase chain reaction (RT-PCR) COVID testing. The purpose of this pictorial review article is to describe the most common manifestations and patterns of lung abnormality on CXR in COVID-19 in order to equip the medical community in its efforts to combat this pandemic. CXR is a less sensitive modality in the detection of COVID-19 lung disease compared to CT, with a reported baseline CXR sensitivity of 69% [[4]Wong H.Y.F. Lam H.Y.S. Fong A.H. et al.Frequency and distribution of chest radiographic findings in COVID-19 positive patients.Radiology. 2019; (Mar 27): 201160https://doi.org/10.1148/radiol.2020201160Crossref PubMed Scopus (844) Google Scholar]. The most common reported CXR and CT findings of COVID-19 include lung consolidation and ground glass opacities2. Ground glass densities observed on CT may often have a correlate that is extremely difficult to detect on CXR (Fig. 1, Fig. 2).Fig. 2CXR (left) with patchy peripheral left mid to lower lung opacities (black arrow) corresponding to ground glass opacities (white arrow) on coronal image from contrast-enhanced the contemporaneous chest CT (right).View Large Image Figure ViewerDownload Hi-res image Download (PPT) Often, reticular opacities accompanying regions of ground glass attenuation are more easily appreciable on standard CXR (Fig. 3). The hazy pulmonary opacities on CXR can sometimes be diffuse making identification challenging in some instances (Fig. 4). As opposed to community acquired bacterial pneumonia which tends to be unilateral and involving a single lobe [[5]Vilar J. Domingo M.L. Soto C. et al.Radiology of bacterial pneumonia.J Eur J Radiol. 2004 Aug; 51: 102-113Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar], COVID-19 and other viral pneumonias typically produce lung opacities in more than one lobe. Identifying multifocal air-space disease on CXR can be a significant clue to COVID-19 pneumonia. Early COVID-19 investigators have noted that the air-space disease tends to have a lower lung distribution and is most frequently bilateral [[4]Wong H.Y.F. Lam H.Y.S. Fong A.H. et al.Frequency and distribution of chest radiographic findings in COVID-19 positive patients.Radiology. 2019; (Mar 27): 201160https://doi.org/10.1148/radiol.2020201160Crossref PubMed Scopus (844) Google Scholar] (Fig. 5). One of the most unique and somewhat specific features of COVID-19 pneumonia is the high frequency of peripheral lung involvement, often mirroring other inflammatory processes such as organizing pneumonia. Chung et al. reported that 33% of COVID-19 chest CTs had peripheral lung distribution [[2]Chung M. Bernheim A. Mei X. et al.CT imaging features of 2019 novel coronavirus (2019-nCoV).Radiology. February 2020; 200230https://doi.org/10.1148/radiol.2020200230Crossref Scopus (1764) Google Scholar] and Ng et al. reported an even greater incidence of up to 86% on chest CT [[6]Ng M.Y. Lee E. Yang J. et al.Imaging profile of the COVID-19 infection: radiologic findings and literature review.Radiol Cardiothorac Imaging. 2020; 2 ([Link, Google Scholar])e200034Crossref PubMed Scopus (689) Google Scholar]. Such peripheral lung opacities also tend to be multifocal, either patchy or confluent, and can be readily identified on CXR (Fig. 6). Diffuse lung opacities in patients with COVID-19 have a similar CXR pattern (Fig. 7) as other widespread infectious or inflammatory processes including acute respiratory distress syndrome (ARDS). When lung disease involves the majority of the pulmonary parenchyma, patients are typically hypoxic and require intubation with mechanical intubation (Fig. 8). Lung opacities may rapidly evolve into a diffuse coalescent or consolidative pattern within 1–3 weeks of symptom onset [[1]Zhou S. Wang Y. Zhu T. Xia L. CT features of coronavirus disease 2019 (COVID-19) pneumonia in 62 patients in Wuhan, China.Am J Roentgenol. 2020; (March): 1-8Crossref PubMed Scopus (434) Google Scholar,[7]Bernheim A. Mei X. Huang M. et al.Chest CT findings in coronavirus disease-19 (COVID-19): relationship to duration of infection.Radiology. 2020; (Feb 20): 200463Crossref PubMed Scopus (1684) Google Scholar], often peaking at around 6–12 days after initial clinical presentation (Fig. 9, Fig. 10).Fig. 10Serial chest radiographs of a different patient with COVID-19 infection separated by 6 days depicting progression of diffuse lung disease requiring intubation.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Pleural effusions have been reported as exceedingly rare on CXR and CT in COVID-19 infected patients, and when present are most often identified late in the disease course [[8]Salehi S. Abedi A. Balakrishnan S. et al.Coronavirus disease 2019 (COVID-19): a systematic review of imaging findings in 919 patients.AJR Am J Roentgenol. 2020 Mar; 14: 1-7https://doi.org/10.2214/AJR.20.23034Crossref Scopus (912) Google Scholar]. Lung cavitation and pneumothorax are also rare findings in COVID-19 patients [[8]Salehi S. Abedi A. Balakrishnan S. et al.Coronavirus disease 2019 (COVID-19): a systematic review of imaging findings in 919 patients.AJR Am J Roentgenol. 2020 Mar; 14: 1-7https://doi.org/10.2214/AJR.20.23034Crossref Scopus (912) Google Scholar] but can occur (Fig. 11). Localized large nodules have yet to be reported in the literature to this date (Fig. 12). Diffuse chest wall subcutaneous emphysema and pneumomediastinum after intubation in the setting of COVID-19 infection has been described in one case report [[9]Sun R. Liu H. Wang X. Mediastinal emphysema, Giant Bulla, and pneumothorax developed during the course of COVID-19 pneumonia.Korean J Radiol. 2020 Mar 20; ([Epub ahead of print])https://doi.org/10.3348/kjr.2020.0180Crossref Scopus (196) Google Scholar], as of the time of this writing. This phenomenon has also been reported previously in the setting of H1N1 viral infection [[10]Gou H.H. Sweeney R.T. Regula D. Fatal 2009 influenza a (H1N1) infection, complicated by acute respiratory distress syndrome and pulmonary interstitial emphysema.Radiographics. 2010 Mar; 30: 327-333https://doi.org/10.1148/rg.302095213Crossref PubMed Scopus (24) Google Scholar]. Since the influx of cases began at our institution, we have noticed this to occur in several patients (Fig. 13). Potential mechanisms include alveolar rupture leading to interstitial emphysema from the currently recommended high positive end-expiratory pressure (PEEP) settings on COVID-19 ventilated patients according to the Macklin effect [[11]Poston JT, Patel BK, Davis AM. Management of critically ill Adults with COVID-19. JAMA Clinical Guideline Synopsis. https://jamanetwork.com/journals/jama/fullarticle/2763879. Accessed March 26, 2020 2020.Google Scholar]. The diffuse alveolar damage in severe cases may also contribute to alveolar rupture. The exact mechanism requires additional investigation. Patterns of COVID-19 lung disease can be identified on conventional chest radiography as well as chest CT. Typical verbiage when reporting patients with, or suspected COVID-19 on CXR include terms such as irregular, patchy, hazy, reticular, and widespread ground glass opacities. Grading disease severity based on total lung involvement is also important to relay to the clinicians. As the pandemic progresses, the medical community will frequently rely on portable CXR due to its widespread availability and reduced infection control issues that currently limit CT utilization.

Portable chest X-ray in coronavirus disease-19 (COVID-19): A pictorial review