CT imaging of pulmonary embolism in patients with COVID-19 pneumonia: a retrospective analysis

Abstract

Objectives: To describe imaging and laboratory findings of confirmed PE diagnosed in COVID-19 patients and to evaluate the characteristics of COVID-19 patients with clinical PE suspicion. Characteristics of patients with COVID-19 and PE suspicion who required admission to the intensive care unit (ICU) were also analysed.

Methods: A retrospective study from March 18, 2020, until April 11, 2020. Inclusion criteria were patients with suspected PE and positive real-time reverse-transcription polymerase chain reaction (RT-PCR) for SARS-CoV-2. Exclusion criteria were negative or inconclusive RT-PCR and other chest CT indications. CTPA features were evaluated and severity scores, presence, and localisation of PE were reported. D-dimer and IL-6 determinations, ICU admission, and previous antithrombotic treatment were registered.

Results: Forty-seven PE suspicions with confirmed COVID-19 underwent CTPA. Sixteen patients were diagnosed with PE with a predominant segmental distribution. Statistically significant differences were found in the highest D-dimer determination in patients with PE and ICU admission regarding elevated IL-6 values.

Conclusion: PE in COVID-19 patients in our series might predominantly affect segmental arteries and the right lung. Results suggest that the higher the D-dimer concentration, the greater the likelihood of PE. Both assumptions should be assessed in future studies with a larger sample size.

Key points: • On CT pulmonary angiography, pulmonary embolism in COVID-19 patients seems to be predominantly distributed in segmental arteries of the right lung, an assumption that needs to be approached in future research. • Only the highest intraindividual determination of d-dimer from admission to CT scan seems to differentiate patients with pulmonary embolism from patients with a negative CTPA. However, interindividual variability calls for future studies to establish cut-off values in COVID-19 patients. • Further studies with larger sample sizes are needed to determine whether the presence of PE could increase the risk of intensive care unit (ICU) admission in COVID-19 patients.

Keywords: COVID-19; Computed tomography angiography; Fibrin fragment D; Intensive care units; Pulmonary embolism.

Fig. 1

Images ordered by score from the upper left to bottom right in mild (a = score 1), moderate-severe (b = score 2), moderate-severe (c = score 3), and severe (d = score 4)

Fig. 2

Segmental left lower lobe PE over a severe lung involvement. CTPA, with lung window (a, b, c) and volume rendering (d) images, shows extensive lung involvement (score 4) with typical findings as reverse halo sign (a, arrow), bilateral peripheral GGO and consolidations with perilobular distribution (b, arrows), and architectural distortion with peripheral sparing (c, arrows). We can also appreciate (e) a small peripheral thrombus (arrow) in a segmental artery of the left lower lobe. Sagittal iodine map image (f) allows us to define segmental vessel obstruction (arrow) and peripheral hypoperfusion (asterisk)

Fig. 3

Segmental left lower lobe and right upper lobe PE. Segmental bilateral embolisms (arrows) can be appreciated in axial (a, b) and oblique MIP and VR images (e, f) over a moderate-severe (score 3) pulmonary involvement (d). Signs of right cardiac overload (black arrow) with interventricular septum shifting towards the left ventricle are shown in c

Fig. 4

Saddle pulmonary embolism. Saddle pulmonary embolism can be appreciated in axial (b) mediastinal window, over a moderate-severe (score 3) pulmonary involvement (c). Iodine map image depicts a hypoperfusion area (a; asterisk) in the right lung

Fig. 5

Bilateral PE with segmental left lower lobe pulmonary infarct over a severe lung involvement. CTPA (a, b, c) shows bilateral thrombi (arrows), one located in the distal portion of a segmental artery of the left lower lobe (c). Pulmonary window image (d) depicts multiple GGO areas and consolidations, with typical peripheral sparing consistent with COVID-19 lung involvement. Iodine map images (e and f) allow us to define right lung hypoperfusion (e; asterisk) and a triangular hypoperfused lesion (f; asterisk), inside the extensive lung involvement and distal to the arterial thrombus, representing a pulmonary infarct