White Matter Microstructural Alterations and Brain Metabolism distributions in Parkinson's Disease

This study aimed to use simultaneous ¹⁸ F-FDG PET/MRI based on Automated Fiber Quantification (AFQ) to determine whether there is a relationship between white matter microstructure changes and glucose metabolism distribution in PD.The study involved 38 subjects, including 23 PD patients and 15 age and sex-matched healthy controls（HC）. Primary clinical data and cognitive assessments were collected. All subjects underwent a simultaneous ¹⁸ F-FDG PET/MR scan. AFQ was utilized to calculate tract-wise diffusion properties of 20 major white matter tracts. PD patients showed reduced mean Mini-Mental State Examination （MMSE） and Montreal Cognitive Assessment （MoCA）scores compared to HC subjects ( P < 0.05). PD patients showed higher mean diffusivity (MD) ( P = 0.047) and axial diffusivity (AD) ( P = 0.02) along the right corticospinal tract (CST) compared to HC. The microstructural change of CST was mainly located in the parietal part (node 67-100). Compared to HC, PD patients had FDG hypermetabolism in the right paracentral lobule ( P = 0.0204) and bilateral putamen (left: P = 0.0075; right: P = 0.0155) and hypometabolism in the right calcarine ( P = 0.0489). Hypermetabolism was found in the right paracentral lobule, which connects with the cortex of the right CST, and positively correlated with MD (r = 0.612, P < 0.001) and AD (r = 0.516, P < 0.001).We observed microstructural changes and glucose metabolism distribution characteristics in PD patients. These results may provide imaging evidence for studying the pathology of PD.