Metabolic characterization of structural lung changes in patients with suggestive COVID-19 pneumonia on 18F-FDG PET/CT

ABSTRACT

Aim/Introduction: Although pulmonary findings of COVID-19 on PET/CT have been previously described, a comprehensive metabolic characterization of diagnostic lung parenchyma changes of COVID-19 pneumonia is still lacking. Our purpose is to evaluate the metabolic uptake of different tomographic signs observed in patients with incidental structural findings suggesting COVID-19 pneumonia through 18F-FDG PET/CT. Material(s) and Method(s) We retrospectively analyzed 596 PET/CT studies performed from February 21, 2020 to April 17, 2020. After excluding 37 scans (PET with non-18F-FDG tracers and brain studies), we analyzed the metabolic activity of several individual structural changes integrated and beyond CO-RADS score through SUVmax of multimodal studies with18F-FDG. Result(s) 43 patients with 18F-FDG PET/CT findings suggestive of COVID-19 pneumonia were included (mean age 68+/-12.3 years, 22 male). SUVmax values were higher in patients with CO-RADS categories 5-6 than in those with lower, nonspecific CO-RADS categories (6.1+/-3.0 vs. 3.6+/-2.1, p=0.004). Groundglass opacities, bilaterality, consolidations, patchy distribution and crazy paving pattern were associated with higher SUVmax values in patients with CO-RADS 5-6 scores (p-values of 0.01, 0.02, 0,01, 0.002 and 0.01, respectively). SUVmax was significantly associated with a positive structural diagnosis of COVID-19 pneumonia (odds ratio=0.63, 95% confidence interval=0.41-0.90;p=0.02). The ROC curve of the regression model aimed to confirm or discard the structural diagnosis of COVID-19 pneumonia showed an AUC of 0.77 (standard error=0.072, p=0.003). Conclusion(s) Multimodal18F-FDG PET/CT is a useful tool during the incidental detection of COVID-19 pneumonia in patients referred for standard oncological and nononcological indications (43/559;7.7%). CT findings characteristic of COVID-19 pneumonia, specifically CO-RADS 5-6, were associated with higher SUVmax.