Western researchers use MRI to learn cause of long-COVID symptoms

File photo of woman coughing. Photo courtesy of © Can Stock Photo / HighwayStarz


A study led by researchers at Western University has revealed the cause of long-COVID symptoms.

New data published by Western professor Grace Parraga and the LIVECOVIDFREE study, based out of five centres in Ontario, is the largest MRI study of patients with long-COVID. The term long-COVID refers to symptoms of brain fog, breathlessness, fatigue and feeling limited while doing everyday things, often lasting weeks and months post-infection.

This is the first study to show a potential cause of long-COVID, which has helped physicians in the study target treatment for the patients.

“I think it is always a conundrum when someone has symptoms, but you can’t identify the problem,” said Parraga, a Tier 1 Canada Research Chair in Lung Imaging to Transform Outcomes at the Schulich School of Medicine and Dentistry. “If you can’t identify the problem, you can’t identify solutions.”

By using MRI imaging with inhaled xenon gas, researchers have identified that the symptoms are caused by microscopic abnormalities that affect how oxygen is exchanged from the lungs to the red blood cells.

Researchers used the technology to watch the function of the 300-500 million tiny alveolar sacs, which are about 1/5 of a millimetre in diameter and responsible for bringing oxygen to the blood.

“What we saw on the MRI was that the transition of the oxygen into the red blood cells was depressed in these symptomatic patients who had had COVID-19, compared to healthy volunteers,” Parraga said.

Further CT scans pointed to ‘abnormal trimming’ of the vascular tree, which indicated an impact on the tiny blood vessels that deliver red blood cells to the alveoli to be oxygenated.

Parraga said the study showed no difference in severity between patients who were hospitalized with COVID-19 and those who recovered without hospitalization. She said this is an important finding as the latest wave of COVID-19 has affected many people who did not receive hospital-based care.

To conduct the study, researchers recruited patients suspected to be suffering from long-COVID from London Health Sciences Centre’s Urgent COVID-19 Care Clinic and St. Joseph’s Health Care London’s Post-Acute COVID-19 Program. Some participants experienced persistent shortness of breath more than six weeks post-infection, while others were still symptomatic after 35 weeks.

One of the participants is Alex Kopacz, a London-native and Canadian Olympic bobsleigh gold-medalist, who called his experience with COVID-19 “harrowing” and believed the virus would not affect him long-term as he is a young athlete.

“I was on oxygen for almost two months after COVID, and it took me almost three months to get to a place where I could go for a walk without gasping for air,” Kopacz said. “The take home message for me is that we have to remember that this virus can have very serious long-term consequences, which are not trivial.”

Researchers are now conducting a one-year follow-up to better understand these results.

The study was done in collaboration with researchers outside of London at Lakehead University, McMaster University, Toronto Metropolitan University and Sick Kids Hospital in Toronto.