Fig. 4

[¹⁸F]FDG PET/CT of a 43-year-old man on the 12th day of acute COVID-19, with respiratory failure, anosmia and ageusia and no other neurological symptoms. Maximum intensity projection (MIP) (A) and coronal PET/CT image fusion of the brain (B) show marked bilateral [¹⁸F]FDG uptake in lenticular nuclei and thalami. Quantitative data are displayed in a rainbow color scale as standard deviation (#StdDev) of the mean uptake of a normal database in C (sagittal slice) and D (coronal slice), including the automatic delimitation of frontal and temporal lobes. Note the reduced metabolism in the frontal and temporal lobes (blue in C and D) and increased metabolism in thalami and brainstem (red in C and D), with an appearance of redistribution of [¹⁸F]FDG uptake from the neocortex to primitive brain structures. An MRI performed three days after PET/CT was totally normal, as seen in sagittal (E) and coronal (F) T1-weighted slices. The patient was followed-up for 12 months and no neurological symptoms or sequelae were detected. Quantification results (in #StdDev units): -2.9 / -3.9, for right / left frontal lobes; -2.0 / -2.4, for right / left temporal lobes; 5.6 / 6.0, for right / left thalami; 4.6, for brainstem