Tracheobronchitis signs observed on ventilation lung scintigraphy during the course of COVID-19 infection.

Ventilation/perfusion scintigraphy remains a method of choice for the diagnostic evaluation of pulmonary embolism (PE) [1], a possible complication of coronavirus disease 2019 (COVID-19) [2]. We report here on lung single-photon emission computed tomography (SPECT) imaging conducted in this setting, using a whole-body CZT SPECT-CT camera (Veriton-CT®), at 10 days from onset of symptoms (fever, dry cough, dyspnea) in a 68-year-old-male non-smoker without any previous history of lung disease, but RT-PCR test positive for COVID-19.

Ventilation images were obtained with 99mTc-labelled Technegas® and blood perfusion images with 99mTc-labelled albumin macro-aggregates. No mismatch indicative of PE was documented on SPECT images; however, peripheral parenchymal lung sequelae were identified on CT images, locally corresponding to decreased dual radiotracer uptake (green arrows).

Moreover, increased tracheobronchial tract uptake of Technegas® was observed (blue arrows), with particularly marked intensity on the proximal bronchi. Increased tracheobronchial uptake of Technegas® has previously been observed in patients with bronchitis or chronic obstructive pulmonary disease [1]. However, such uptake is uncommon in non-smoking patients without any prior history of lung disease and was particularly marked here, suggesting a tracheobronchitis. The endothelial lining of the respiratory track is vulnerable to severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection, due to high ACE2 receptor expression [3, 4], and the present observation suggests that signs of a tracheobronchitis may be detected by lung scintigraphy in the course of COVID-19 infection. Although the mechanism is presumably not specific to the SARS-CoV2 virus, such signs might have diagnostic and therapeutic applications, especially in the absence of any previous history of pulmonary disease.