COVID-19 mimics on chest CT: a pictorial review and radiologic guide

Abstract

Chest imaging is often used as a complementary tool in the evaluation of coronavirus disease 2019 (COVID-19) patients, helping physicians to augment their clinical suspicion. Despite not being diagnostic for COVID-19, chest CT may help clinicians to isolate high suspicion patients with suggestive imaging findings. However, COVID-19 findings on CT are also common to other pulmonary infections and non-infectious diseases, and radiologists and point-of-care physicians should be aware of possible mimickers. This state-of-the-art review goal is to summarize and illustrate possible etiologies that may have a similar pattern on chest CT as COVID-19. The review encompasses both infectious etiologies, such as non-COVID viral pneumonia, Mycoplasma pneumoniae, Pneumocystis jiroveci, and pulmonary granulomatous infectious, and non-infectious disorders, such as pulmonary embolism, fat embolism, cryptogenic organizing pneumonia, non-specific interstitial pneumonia, desquamative interstitial pneumonia, and acute and chronic eosinophilic pneumonia.

Figure 1.

51-year-old patient presenting with CT findings of COVID-19 confirmed by RT-PCR. (a) Axial chest CT in lung windows demonstrates bilateral predominantly peripheral ground-glass attenuation without consolidation. (b) Coronal reformatted CT shows bilateral ground-glass attenuation without a significant gradient. RT-PCR, reverse transcription polymerase chain reaction.

Figure 2.

58-year-old male with Influenza A H1N1 pneumonia. Axial CT image demonstrates a predominant pattern of consolidation with diffuse distribution, air bronchograms, and sparse ground-glass opacities.

Figure 3.

67-year-old male with adenovirus pneumonia. (a, b) Axial CT images demonstrate areas of consolidation with peripheral distribution, lower lobe predominance, and interlobular septal thickening.

Figure 4.

48-year-old female with non-Hodgkin lymphoma and Mycoplasma pneumoniae infection. (a–d) Axial CT images demonstrate random centrilobular nodules with ground-glass and solid attenuation, bronchial wall thickening and consolidations predominantly in the lower lobes.

Figure 5.

32-year-old male with acquired immunodeficiency syndrome and Pneumocystis jiroveci pneumonia. (a, b) Axial CT images demonstrate ground-glass opacities and intralobular septal thickening in the periphery of the upper lobes and the superior segments of the lower lobes.

Figure 6.

58-year-old male with paracoccidioidomycosis. (a–c) Axial and (d) coronal CT images demonstrate diffuse ground-glass lesions in a random distribution, some with a peripheral rim of consolidation yielding the reversed halo sign and some solid nodules.

Figure 7.

48-year-old male with pulmonary embolism. (a) Axial CT image demonstrate a wedge-shaped peripheral lung opacity in the right lower lobe with a ground-glass core and a peripheral rim of consolidation yielding the reversed halo sign. (b) CT angiography evidencing the thrombus in the right interlobar artery.

Figure 8.

27-year-old male victim of a motorcycle accident with multiples injuries and developed respiratory distress a couple of days after the trauma due to fat embolism. (a) Three-dimensional rendering reconstruction of CT images demonstrates tibial and fibular fracture. (b) Axial CT image and (c) coronal maximum intensity projection reconstruction demonstrate patchy ground-glass opacities in the lower lobes with subpleural sparing.

Figure 9.

57-year-old female with cryptogenic organizing pneumonia. (a) Axial and (b) coronal CT images shows bilateral perilobular opacities, interlobular septal thickening, and the reversed halo sign (arrow).

Figure 10.

61-year-old male with amiodarone-induced organizing pneumonia. (a, b) Axial CT images with peripheral and bilateral areas of ground-glass lesions in random distribution and with some reticular opacities.

Figure 11.

49-year-old female with non-specific interstitial pneumonia. (a–c) Axial and (d) coronal CT images demonstrate reticulations in the subpleural zones, predominantly in the lower lobes, with some ground-glass opacities and bronchiectasis.

Figure 12.

44-year-old male, smoker, with desquamative interstitial pneumonia. (a–c) Axial CT images demonstrate ground-glass and reticular opacities in the periphery of the lower lobes and the middle lobe.

Figure 13.

40-year-old male with acute eosinophilic pneumonia. Axial CT demonstrates bilateral and peripheral ground-glass opacites with interlobular septal thickening.