Structure and Function of Long-COVID Evaluated Using Pulmonary Imaging

Harkiran Kaur Kooner, The University of Westen Ontario

Abstract

The COVID-19 pandemic has resulted in millions of global respiratory infections, ranging in severity from asymptomatic to fatal. One of the many consequences of the pandemic is the emergence of long-COVID, which is an umbrella term used to describe the long-term sequelae and poor quality-of-life following recovery from acute COVID-19 infection. However, the pathophysiology and mechanisms responsible for the heterogenous manifestation of long-COVID remain poorly understood. Hyperpolarized ¹²⁹Xe magnetic resonance imaging (MRI) provides a non-invasive and radiation-free method to regionally visualize and quantify inhaled gas distribution and ventilation in vivo. A strong foundation for the use of pulmonary imaging in asthma and chronic obstructive pulmonary disease (COPD) to strengthen our grasp of disease processes suggests the utility of imaging in long-COVID. Accordingly, the objective of this thesis was to develop a deeper understanding of the structure and function of long-COVID using hyperpolarized ¹²⁹Xe MRI in tandem with structural computed tomography (CT) imaging. First, we investigated a group of long-COVID participants three months post-infection and observed an increased ventilation defect percent (VDP) in ever- as compared to never-COVID participants. At a follow-up visit one year later, we reported a significant improvement in VDP and the use of airways disease medication increasing the odds of quality-of-life improvement. We then contextualized CT airway sex differences in long-COVID participants by reporting similarities in CT evidence of airway remodelling for females with long-COVID and ex-smokers with and without COPD. Finally, we showed that MRI ventilation textures were predictive of one year improvement in quality-of-life, outperforming VDP and clinical measurements. Taken together, these results suggest an airways disease component to long-COVID that can help guide clinical decision making and improve patient outcomes.