Vasculitis changes in COVID-19 survivors with persistent symptoms: an [¹⁸F]FDG-PET/CT study

Several patients experience unexplained persistent symptoms after SARS-CoV-2 recovering. We aimed at evaluating if 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) was able to demonstrate a persistent inflammatory process.

Recovered adult COVID-19 patients, who complained unexplained persisting symptoms for more than 30 days during the follow-up visits, were invited to participate in the study. Patients fulfilling inclusion criteria were imaged by [¹⁸F]FDG positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT). Whole-body [¹⁸F]FDG-PET/CT, performed according to good clinical practice, was qualitatively (comparison with background/liver) and semi-quantitatively (target-to-blood pool ratio calculated as average SUVmax artery/average SUVmean inferior vena cava) analyzed. Negative follow-up [¹⁸F]FDG-PET/CT images of oncologic patients matched for age/sex served as controls. Mann-Whitney test was used to test differences between groups. SPSS version 26 was used for analyses.

Ten recovered SARS-CoV-2 patients (seven male and three females, median age 52 years, range 46-80) with persisting symptoms were enrolled in the study. Common findings at visual analysis were increased [¹⁸F]FDG uptake in bone marrow and blood vessels (8/10 and 6/10 cases, respectively). [¹⁸F]FDG uptake in bone marrow did not differ between cases and controls (p = 0.16). The total vascular score was similar in the two groups (p = 0.95). The target-to-blood pool ratio resulted higher in recovered SARS-CoV-2 patients than in controls.

Although the total vascular score was similar in the two groups, the target-to-blood pool ratio was significantly higher in three vascular regions (thoracic aorta, right iliac artery, and femoral arteries) in the recovered COVID-19 cohort than in controls, suggesting that SARS-CoV-2 induces vascular inflammation, which may be responsible for persisting symptoms.