Investigation of perfusion defects by Q-SPECT/CT in patients with mild-to-moderate course of COVID-19 and low clinical probability for pulmonary embolism

Abstract

Objective: Pulmonary embolism is a severe source of mortality and morbidity in patients with severe and critical coronavirus disease 2019. It is not yet clear whether the tendency to thrombosis is increased in the mild-to-moderate course of COVID-19. Our research aims to show the clinical benefit of Q-SPECT/CT in diagnosing PD in outpatients treated with mild-to-moderate course of COVID-19 and to determine the frequency of perfusion defects in these patients having relatively lower risk.

Methods: All patients who underwent Q-SPECT/CT with suspicion of embolism were examined retrospectively. Only patients with low clinical probability and mild-to-moderate course of COVID-19 for PE were included in the study. The patients were evaluated comparatively as those with and without perfusion defects. Patients were divided into laboratory suspicion, clinical suspicion, or clinical and laboratory suspicion.

Results: In outpatients with mild-to-moderate COVID-19 with low clinical probability for PE, PD without CT abnormality was detected with a rate of 36.6% with Q-SPECT/CT performed for complaints of high D-dimer and/or dyspnea. None of the patients had PD at more proximal level than the segment level. PD with no concomitant CT abnormality was observed with a rate of 56.5% in patients with both clinical and laboratory suspicion. For D-dimer = 0.5 mg/dL cut-off sensitivity is 85%, for D-dimer = 1.5 mg/dL cut-off specificity 81%.

Conclusion: Thrombosis tendency is also present in outpatients with mild-to-moderate COVID-19, and these patients should also be offered anticoagulant prophylaxis during the COVID-19 period.

Keywords: COVID-19; Pandemic; Perfusion defects; Pulmonary embolism; Q-SPECT/CT.

Fig. 1

A sample Q-SPECT/CT images-1. Image 1: Perfusion defect with segmental wedge-style in the superior segment of the lower lobe of the right lung, incompatible with CT

Fig. 2

A sample Q-SPECT/CT images-2. Image 2: Multiple peripherally located subsegmental perfusion defects in bilateral lung parenchyma areas, incompatible with CT

Fig. 3

A sample Q-SPECT/CT images-3. Image 3: Segmentary perfusion defect in the upper lobe anterior segment of the left lung, incompatible with CT

Fig. 4

d-dimer ROC curve. The test result variable (s): Q-SPECT/CT, d-dimer, has at least one tie between the positive actual and negative actual state groups. The smallest cut-off value is the minimum observed test value minus 1, and the most considerable cut-off value is the maximum observed test value plus 1. All the other cut-off values are the averages of two consecutive ordered observed test values