Dual-Energy CT Pulmonary Angiography Quantifies Vasculopathy in Severe COVID-19 Pneumonia

Abstract

S evere acute respiratory failure is the dominant cause of death in patients with coronavirus disease 2019 (CO-VID-19) (1). The pathophysiology and imaging features of severe COVID-19 pneumonia have been the focus of considerable interest from the outset of the pandemic. In early disease, widespread ground-glass opacification predominates at thoracic CT (2-6) and is supposedly associated with highly compliant lungs and disrupted vasoregulation (7). Vascular dysregulation is believed to be consequence of exaggerated activation of inflammatory and coagulation cascades (termed immunothrombosis) (1,(8)(9)(10)(11)(12). Later in the course of disease, CT more commonly shows consolidation and fibrosis associated with lower lung compliance (13).There is growing evidence from radiologic and pathologic studies of a significant vasculopathy in COVID-19 pneumonia (14-17); in a recent study of postmortem lungs in COVID-19, there were widespread microthromboses and striking new vessel formation (16). Furthermore, based on qualitative analyses, a number of studies have highlighted the potential role of dual-energy CT pulmonary angiography (DECTPA) (15,(18)(19)(20)(21). Accordingly, in the present study, we aimed to evaluate the relationships between a quantitative measure of perfusion at DECTPA (relative perfused blood volume [PBV], ie, PBV relative to pulmonary artery enhancement [PBV/PAenh]) ( 22) and (a) disease duration, (b) right ventricular dysfunction (RVD) at echocardiography, (c) d-dimer levels, and (d) obstruction score (23) in patients with severe COVID-19 pneumonia. A secondary aim was to compare PBV/PAenh in COVID-19 pneumonia to that of healthy volunteers.

Assessment of pulmonary arterial circulation 3 months after hospitalization for SARS-CoV-2 pneumonia: Dual-energy CT (DECT) angiographic study in 55 patients

“…These abnormalities could represent unresolved/sequelae of the widespread microangiopathy described in the acute phase of the disease, characterized by occlusion of alveolar capillaries. During COVID-19 pneumonia, mottled defects were present in almost all patients scanned with DECT [ 17 , 18 ].…”

“…Their distribution was rated as unilateral/bilateral; central/peripheral. We also searched for the presence of vascular features described in the acute phase of COVID-19 pneumonia, i.e., the “vascular tree-in-bud” pattern and abnormally dilated peripheral vessels [17] . The presence, extent and severity of comorbid conditions that might interfere with CT lung perfusion analysis, i.e., emphysema and interstitial lung disease, was also recorded.…”

“…In comparison with autopsy findings in influenza-associated respiratory failure, alveolar capillary microthrombi were found to be 9 times more prevalent in patients with COVID-19 who also exhibited a 2.7 times higher amount of new vessel growth [13] . In-vivo insight into this distal pulmonary angiopathy was reported in patients with mild to severe COVID-19 pneumonia who underwent dual-energy CT angiography [15] , [16] , [17] , [18] , [19] , [20] . In the early clinical phase, increased lung perfusion matching with ground-glass opacities was reported.…”

Rescue therapy with thrombolysis in patients with severe COVID‐19‐associated acute respiratory distress syndrome

“… 5 – 7 RVD may be severe, 8 and associated with pulmonary microthrombosis early in the disease course. 9 …”

Ventilator-Associated Lung Injury

“…4 ) ( Vieillard-Baron et al, 2013 ; Boissier et al, 2013 ; Chiumello and Pesenti, 2013 ). This coupling between the pulmonary vasculature and the right ventricle was particularly important in ARDS induced by more vascular inflammation as experienced globally during the coronavirus pandemic ( Patel et al, 2020 ; Ridge et al, 2020 ; Tavazzi et al, 2019 ; Bleakley et al, 2020 ).

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