About the source and consequences of 18F-FDG brain PET hypometabolism in short and long COVID-19

Abstract

We have readwith great interest the article recently published by Guedj et al., titled F-FDG brain PET hypometabolism in patients with long COVID [1]. We recently proposed that PET imaging versatility might hold the key for understanding pathophysiological changes in the brain of COVID-19 patients [2]. The article by Guedj and colleagues is a great demonstration of how powerful PET imaging can be in this regard. This article provides evidence that COVID-19 patients with persistent functional complaints, more than 3 weeks after the first symptoms, present continuous F-FDG PET hypometabolism in multiple brain regions, including the olfactory gyrus, hippocampus and cerebellum. Few months ago, small-scale studies provided initial evidence of brain glucose hypometabolism in COVID-19 individuals [3, 4] sharing similar findings concerning the hypometabolic brain regions, such as the pre-frontal cortex and the gyrus rectus. Our letter intends to raise awareness on (1) the biological interpretation of decreased brain F-FDG PET signal in COVID-19 and (2) potential sequelae due to brain glucose hypometabolism in long COVID. Cellular origins of F-FDG PET hypometabolism in COVID-19