Chest computed tomography and plain radiographs demonstrate vascular distribution and characteristics in COVID-19 lung disease - a pulmonary vasculopathy

Abstract

Introduction: Early in the COVID-19 pandemic, CT was demonstrated as a sensitive tool for diagnosing COVID-19. We undertook a detailed study of CT scans in COVID-19 patients to characterise disease distribution within lung parenchyma, respiratory airways, and pulmonary vasculature, aiming to delineate underlying disease processes.

Methods: We characterised acute phase chest CT of 40 participants with COVID-19 from the REACT study, 31 with CT pulmonary angiography (CTPA), 4 with intravenous contrast enhanced CT and 5 with non-intravenous contrast enhanced CT. Participants had neither been vaccinated nor received systemic steroids. We further correlated the distribution of lung parenchymal damage on CT with contemporaneous chest radiographs.

Results: Parenchymal lung damage was found in all subjects. However, airways inflammation was present in only 23% (9) and limited to small areas. Notably, vascular abnormalities were dominant and characterised by dilated peripheral pulmonary vessels supplying areas of lung damage in a gravity-dependent distribution bilaterally in 95% (38), basally in 90% (36), peripherally in 92.5% (37), and posteriorly in 90% (36). Macrothrombosis was demonstrated in 23% (7) of CTPAs. Wedge-shaped peripheral lung damage, resembling areas of pulmonary vascular congestion, were distinct in 53% (21) with or without visible macrothrombosis. Pleural effusions were seen in 28% (11). Notably, lung opacification distribution in 98% of the plain radiographs matched distribution on CT (39).

Conclusion: Our study frames COVID-19 as a pulmonary vasculopathy rather than a more conventional pneumonia which may be important not only for guiding mechanistic study design but also for the development of novel targeted therapeutics.

Keywords: COVID-19; CT imaging; Chest Radiographs; Respiratory Infections; Vasculopathy.

Figure 1. CT chest of a patient with COVID-19 lung disease showing areas of consolidation (arrows) and GGOs (arrowheads) in a peripheral, posterior and basal distribution bilaterally.

Figure 2. CT chest of a patient with COVID-19 showing areas of lung damage (GGO or consolidation) accompanied by dilated blood vessels (arrowheads). Analysis showed dilatation of both the pulmonary arteries and veins in these areas of lung damage.

Figure 3. (A) CT chest in a patient with COVID-19 lung disease showing vascular tree-in-bud opacification in isolation of lung damage. (B) CT chest in a patient with COVID-19 lung disease showing vascular tree-in-bud opacification in an area of lung damage. This phenomenon was not considered a feature distinct from dilated vessels within GGOs.

Figure 4. CT chest in a patient with COVID-19 lung disease showing multiple areas of wedge-shaped lung damage in the lung peripheries (analogous to pulmonary infarcts or areas of vascular congestion in the context of conventional pulmonary thromboembolic disease).

Figure 5. (A) CT and (B) contemporaneous chest radiograph in a patient with COVID-19 lung disease. The typical distribution of opacification due to lung damage shown on CT (bilateral, basal, peripheral, and posterior) is matched by bilateral, basal and peripheral distribution of opacification on the contemporaneous radiograph.