Role of CT angiography in detecting acute pulmonary embolism associated with COVID-19 pneumonia

Abstract

Purpose: Recently coronavirus disease (COVID-19) caused a global pandemic, characterized by acute respiratory distress syndrome (ARDS). The aim of our study was to detect pulmonary embolism (PE) in patients with severe form of COVID-19 infection using pulmonary CT angiography, and its associations with clinical and laboratory parameters.

Methods: From March to December 2020, we performed a prospective monocentric study collecting data from 374 consecutive patients with confirmed SARS-CoV-2 infection, using real-time reverse-transcriptase polymerase-chain-reaction (rRT-PCR) assay of nasopharyngeal swab specimens. We subsequently selected patients with at least two of the following inclusion criteria: (1) severe acute respiratory symptoms (such as dyspnea, persistent cough, fever > 37.5 °C, fatigue, etc.); (2) arterial oxygen saturation ≤ 93% at rest; (3) elevated D-dimer (≥ 500 ng/mL) and C-reactive protein levels (≥ 0.50 mg/dL); and (4) presence of comorbidities. A total of 63/374 (17%) patients met the inclusion criteria and underwent CT angiography during intravenous injection of iodinated contrast agent (Iomeprol 400 mgI/mL). Statistical analysis was performed using Wilcoxon rank-sum and Chi-square tests.

Results: About, 26/60 patients (40%) were found positive for PE at chest CT angiography. In these patients, D-dimer and CRP values were significantly higher, while a reduction in SaO2 < 93% was more common than in patients without PE (P < 0.001). Median time between illness onset and CT scan was significantly longer (15 days; P < 0.001) in patients with PE. These were more likely to be admitted to the Intensive Care Unit (19/26 vs. 11/34 patients; P < 0.001) and required mechanical ventilation more frequently than those without PE (15/26 patients vs. 9/34 patients; P < 0.001). Vascular enlargement was significantly more frequent in patients with PE than in those without (P = 0.041).

Conclusions: Our results pointed out that patients affected by severe clinical features of COVID-19 associated with comorbidities and significant increase of D-dimer levels developed acute mono- or bi-lateral pulmonary embolism in 40% of cases. Therefore, the use of CT angiography rather than non-contrast CT should be considered in these patients, allowing a better evaluation, that can help the management and improve the outcomes.

Keywords: ARDS; COVID-19; CT angiography; Pulmonary embolism.

Fig. 1

Time interval between symptoms onset and CT angiography in patient without (0, 00) and with pulmonary embolism (1, 00). Median value: 6 days versus 15 days (P < 0.001)

Fig. 2

Pulmonary CT angiography of a 67-year-old male with acute pulmonary embolism. The CT scan was obtained six days after the onset of COVID-19 symptoms; on the same day the patient was transferred to the intensive care unit. A, Axial scan in mediastinal window shows linear saddle embolism of the pulmonary trunk (black arrow) and multiple bilateral filling defects involving lobar arterial branches (white arrows). B, Axial scans in lung window shows vascular enlargement (black arrowheads) and peripheral ground-glass opacities involving both lungs

Fig. 3

Pulmonary CT angiography of a 78-year-old male obtained 17 days after the onset of COVID-19 symptoms. A, B Axial contrast-enhanced CT scan shows bilateral filling defects involving lobar branches of the pulmonary artery (white arrows). C, D, Axial CT images (lung window) show peripheral ground-glass opacities with associated areas of consolidation, lung architectural distortion and vascular enlargement (black arrowheads)