Fig. 1.

Schematic overview of youthful brain metabolism calculation. Separate resting PET and MRI scans were obtained in individuals. PET scans were preprocessed and then combined with MRI to calculate partial volume corrected regional standardized uptake value ratio (SUVR) values in the gray matter. Each individual map of brain metabolism and CBF was then compared to the corresponding group map obtained in the separate N33 young adult cohort using a Spearman correlation. The final rho value was used as the “youthful metabolic index” for that individual and specific metabolic parameter (GI, FDG, oxygen metabolism, and CBF). (Figures are intended for schematic purposes only.)