Coupling between Human Brain Cortical Thickness and Glucose Metabolism from Regional to Connective level: a PET/MRI study

OBJECTIVES: Disruption of the balance between brain structure and function is implicated in many brain disorders. This study aimed to investigate the coupling between the brain cortical thickness (CTh) and glucose metabolism using 18F-FDG PET/MRI. METHODS: 138 subjects who performed brain 18F-FDG PET/MRI were retrospectively recruited and divided into two groups according to their ages. The Spearman’s rank correlation was calculated between the FDG uptakes and CTh across the cortex for each subject to explore the structural and functional coupling (S-F coupling) at the regional level, which was then correlated with age to explore its physiological effects. Structural connectivity (SC) based on CTh and functional connectivity (FC) based on glucose metabolism were constructed followed by exploring the network similarity and coupling between SC and FC. The global and local efficiency of the brain SC and FC were also evaluated. RESULTS: 97.83% of subjects exhibited a significant negative correlation between regional CTh and FDG uptakes (p<0.05 with FDR correction), and this S-F coupling was negatively correlated with age (r=-0.35, p<0.001). At the connective level, SC-FC coupling was almost positive, with more regions in the old age group exhibiting significant coupling than in the middle age group. Besides, FC exhibited denser connections than SC, resulting in both higher global and local efficiency, but lower global efficiency when the network size corrected. CONCLUSION: This study found there is a coupling between CTh and glucose metabolism from the regional to connective level. These findings may have implications for the diagnosis and treatment of neurological and psychiatric disorders. CLINICAL RELEVANCE STATEMENT: The observed coupling between brain cortical thickness and glucose metabolism, both at the regional and connective level provides insights into the brain mechanisms and highlights potential implications for the diagnosis and treatment of neurological and psychiatric disorders.