Lung VQ scan in COVID-19: Various patterns of perfusion defects

ABSTRACT

Aim/Introduction: While COVID-19 infection is associated with the increased risk of pulmonary thromboembolism (PTE), it may also affects the lungs that causes ventilation-perfusion (VQ) patterns other than PTE. Although extensive research has been done to address different anatomical patterns of COVID-19, there is a knowledge gap in terms of VQ lung scintigraphy in these patients. The purpose of this study is to demonstrate these patterns and to show how important it is to use SPECT/CT in addition to planar images to differ these patterns from PTE [1, 2, 3]. Material(s) and Method(s) We collected lung scans performed in 64 patients with history of past/recent COVID-19 infection (in the preceding 1.5 years) who were referred for VQ scintigraphy. The scan was performed using Q-SPECT/Q-planar (26.6%), Q-SPECT/CT (42.2%), VQ-SPECT (14%) and VQ-SPECT/CT (17.2%). Interpretation was based on the EANM criteria. Result(s) Of these patients 10 (15.6%) had positive scan for PTE. Moreover, in 49 (76.6%) of these patients, anatomical abnormalities were observed compatible with COVID-19 infection. The patterns seen were as follows 1) apparent hot spot due to focal sparing of lung, 2) zones of decreased and increased perfusion, 3) zones of normal and increased perfusion, 4) small sub-segmental defects matching with CT findings, and 5) reverse mismatched defects. Also, a case of loculated pleural effusion in CT with Q abnormalities was observed. Conclusion(s) Lung perfusion abnormalities are common findings in COVID-19 patients. They are usually either due to pulmonary embolism, parenchymal infiltrates, or other causes of mosaic attenuation related to, but not specific of the pathophysiology of COVID-19 infection. The value of VQ SPECT/CT imaging to detect and differentiate the various types of Q abnormalities was noticeable.