Increased cerebral blood flow and neuroinflammation post COVID-19

ABSTRACT

Aim/Introduction: Persisting cerebral symptoms such as fatigue and cognitive dysfunction after Sars-CoV-2 infection are typical for post COVID-19. Positron emission tomography (PET) can contribute to the understanding of post COVID-19 related brain disorders. The aim of this study was to investigate cerebral blood flow (CBF) and neuroinflammation with PET in post COVID-19 patients. Material(s) and Method(s) Data from eight healthy controls (HC) and four subjects with post COVID-19 symptoms were included. At the time of the PET investigation, three subjects had remaining post COVID-19 symptoms, of which one had severe headache. All subjects underwent a 6 min dynamic 15O-water PET scan to measure CBF and a 60 min dynamic 11CPK11195 PET scan to measure neuroinflammation. In addition, all subjects received a T1weighted MRI that was co-registered to the PET images. Parametric images, showing 15O-water CBF and 11CPK11195 binding potential (BPND) at the voxel level, were calculated. Mean total grey matter CBF and BPND values were calculated for all subjects. The co-registered MRI images were normalized to MNI standard space using statistical parametric mapping (SPM12) and the transformation matrices were applied to the respective parametric images. A voxel-wise z-test was performed in SPM12 to compare each 15Owater CBF and 11CPK11195 BPND image from the post COVID-19 patients to the HC CBF and BPND images, respectively. A statistical threshold of p<0.05 was applied. Result(s) Two of the subjects with remaining post COVID-19 symptoms demonstrated a significantly increased CBF in the whole brain compared to the HC. Total grey matter CBF values were 1.27 and 1.41 mL/cm3/min in these two subjects, compared to a mean +/- SD of 0.65 +/- 0.19 mL/cm3/min in the HC group. The subject with persisting headache also showed large clusters of significant increased 11C-PK11195 BPND in the meninges. Mean total grey matter 11CPK11195 BPND values in post COVID-19 subjects were within the range of values in the HC group. The other two subjects did not show increased CBF and no significant increase of 11C-PK11195 BPND. Conclusion(s) Neurological symptoms from post COVID-19 may be due to increased CBF and inflammation. However, further investigations are needed with larger study cohort to better understand the relation between post COVID-19 symptoms and neurological dysfunctions investigated with PET.