Imaging algorithm for COVID-19: A practical approach

Abstract

The global pandemic of COVID-19 pneumonia caused by the novel coronavirus (SARS-CoV-2) has strained healthcare resources across the world with emerging challenges of mass testing, resource allocation and management. While reverse transcriptase-polymerase chain reaction (RT-PCR) test is the most commonly utilized test and considered the current gold standard for diagnosis, the role of chest imaging has been highlighted by several studies demonstrating high sensitivity of computed tomography (CT). Many have suggested using CT chest as a first-line screening tool for the diagnosis of COVID-19. However, with advancement of laboratory testing and challenges in obtaining a CT scan without significant risk to healthcare providers, the role of imaging in diagnosis has been questioned. Several imaging societies have released consensus statements and guidelines on utilizing imaging resources and optimal reporting. In this review, we highlight the current evidence on various modalities in thoracic imaging for the diagnosis of COVID-19 and describe an algorithm on how to use these resources in an optimal fashion in accordance with the guidelines and statements released by major imaging societies.

Keywords: COVID-19; Chest radiograph; Computed tomography; SARS-CoV-2; Thoracic imaging in COVID-19.

Fig. 1

Initial imaging findings in COVID-19. (A) Chest CT shows bilateral, peripheral, patchy ground-glass opacities in both lungs, right worse than left. (B) Portable CXR is near normal with very subtle peripheral opacities in the mid lung zones and left base.

Fig. 2

Rapid progression to ARDS in COVID-19. (A) Chest CT shows worsening consolidation which is more pronounced in the bilateral lower lobes. (B) Portable CXR obtained a few days prior to CT shows early development of consolidative changes in the bilateral posterior lung bases.

Fig. 3

Secondary bacterial pneumonia in patient of COVID-19. (A) Chest CT shows dense right lower lobe consolidation with air-bronchograms due to secondary bacterial pneumonia. Mild consolidation is seen in the left lower lobe. (B) Portable CXR obtained a day later, shows progression of dense consolidation in the right lower lobe as well as right upper lobe and left lung.

Fig. 4

Persistent opacities with imaging signs of early organization. (A) Chest CT shows persistent ground-glass opacities with lobular areas of sparing in the non-dependent areas and organized consolidations in the dorsal/dependent portions of both lungs. (B) Portable CXR obtained a few days after CT, shows progression of dense consolidations in both lungs with mid and lower zone predominance.

Fig. 5

Early-onset extensive fibrosis and bronchiectasis in COVID-19. Chest CT shows peribronchial fibrotic consolidations and ground-glass opacities with development of traction bronchiectasis mainly in the right lower and middle lobes.

Fig. 6

Necrotizing pneumonia with COVID-19. CT chest shows a cavitary lesion in the middle lobe suggestive of necrotizing pneumonia with lung abscess due to secondary bacterial pneumonia. There are diffuse ground-glass opacities and lower lobe consolidations due to COVID-19. Note, small right pneumothorax.

Fig. 7

Large bullous disease with pneumothorax in COVID-19. (A) Chest CT shows bullae in the anterior basilar segment right lower lobe and superior lingula, with dense consolidations in both lower lobes. (B) Follow-up chest CT shows development of a large multi-loculated, tension right pneumothorax due to ruptured bulla, resulting in contralateral mediastinal shift.

Fig. 8

Proposed algorithm for imaging in patients with suspected COVID-19 pneumonia.