Fig. 6: Simultaneous imaging of activated lymphocytes and adipocytes with [¹⁸F]F-AraG reveals concurrent neuroinflammation and BAT activation in a post-acute COVID subject.

a–d [¹⁸F]F-AraG PET/MR images of a COVID-naïve subject. a Transverse PET brain slice shows signal in the choroid plexus but no neuroinflammation. b Coronal PET/MR slice shows low signal in the supraclavicular brown fat depots. c Transverse T1 weighted MR slice shows hypersignal in the supraclavicular fat deposits (white arrowheads). d The supraclavicular fat deposits show low [¹⁸F]F-AraG PET signal (white arrowheads). e–h [¹⁸F]F-AraG PET/CT images of a post-acute COVID subject. e Transverse PET brain slice shows signal in the choroid plexus and a diffuse signal at the confluence of sinuses indicating neuroinflammation (yellow arrowhead). f Coronal PET/CT slice shows [¹⁸F]F-AraG uptake in the cervical and supraclavicular brown fat depots (white arrowheads). g Transverse CT slice shows hyposignal in the cervical fat deposits (white arrowheads). h Cervical fat deposits show high [¹⁸F]F-AraG PET signal (white arrowheads). i Sagittal view shows low uptake in the lumbar bone marrow of a COVID-naïve subject (white arrowhead). j Transverse slice shows minimal uptake in the L4 vertebrae of a COVID-naïve subject. k In the post-acute COVID subject high signal in the lumbar bone marrow is observed (white arrowhead) (l). Transverse slice shows high [¹⁸F]F-AraG uptake in the L4 vertebrae of a post-acute COVID subject.