Analysis of brain metabolism using FDG-PET/CT in patients with acute Covid-19

ABSTRACT

Aim/Introduction: Neurological sequelae of Covid-19 have been widely documented by anatomic and functional methods [1,2]. Brain metabolism studies using 18F-FDG PET/CT during the subacute phase of the disease have also been published [1]. On the other hand, there is a lack of information about the influence of SARS-Cov2 infection on brain metabolism during the acute phase of the disease. The aim of this study was to identify and quantify changes in brain metabolism during the acute onset of Covid-19. Material(s) and Method(s) We studied 23 patients (13 women, median age 55.5[33-78] years) hospitalized with positive nasopharyngeal swab test (RT-PCR) for Covid-19 and requiring supplemental oxygen. Dedicated PET/CT images of the brain were acquired for 10 minutes, 1h after injection of 4.4 MBq/kg of 18F-FDG. Visual analysis was performed by two nuclear medicine specialists and one radiologist. Quantitative analysis was performed using dedicated software. 18F-FDG uptake in multiple brain regions was evaluated and the standard deviation (SD) of brain uptake in each region was automatically calculated in comparison with a group of normal subjects. More than 2 SD above or below the control group was considered significant in each area. Result(s) Serum C-reactive protein at admission ranged from 6.43 to 189.0 mg/L (mean 97.0 +/- 55.5 mg/L). The mean supplemental oxygen demand was 2.8 +/- 1.5 L/min. PET/CT images were acquired between 4 and 20 days of symptoms (mean 12.9 +/- 3.8 days). The images showed increased glycolytic metabolism in basal ganglia and relatively reduced brain metabolism in cortical regions. Basal ganglia metabolism was bilaterally increased in 18/23 (78.3%) and normal in 5 (21.7%) patients. Lenticular nucleus presented increased metabolism in 21/23 (91.3%) and was normal in 2 (8.7%) patients. Frontal and parietal lobes metabolism was respectively reduced in 9/24 (37.6%) and 8/23 (34.8%) patients. The whole brain metabolism was normal in 20/23 (86.9%) patients. Olfactory cortex metabolism was normal in 18/23 (78.3%) patients. Conclusion(s) Brain metabolism is clearly affected during the acute phase of SARS-Cov2 infection. The most frequent finding was increased basal ganglia metabolism, with most patients presenting marked lenticular nucleus hypermetabolism. Frontal and parietal lobes presented reduced metabolism in some patients. Interestingly, olfactory cortex is not affected in most patients, suggesting that anosmia, reported by some patients, is not related to the direct involvement of the brain by the disease.