Evaluation of metabolic changes in Parkinson's disease patients with different severities of cognitive impairments by 18F-FDG PET/CT brain imaging

Abstract

Objective To investigate the characteristics of cerebral glucose metabolism (CGM) in PD patients with cognitive impairment (PD-CI) using 18F-FDG PET/CT, and to analyze the correlation between the progress of PD-CI and CGM changes. Methods A total of 31 idiopathic PD patients (14 males, 17 females, aged 37-77 years) from May 2013 to February 2014 were divided into 3 groups based on Montreal cognitive assessment (MOCA): none CI in PD (PD-NC) group (MOCA>26 scores), mild CI in PD (PD-MCI) group (MOCA 21-26 scores), PD with dementia (PDD) group (MOCA<21 scores). The normal controls (NC) group included 12 age- and gender-matched healthy adults (7 males, 5 females, aged 40-76 years). All subjects underwent PET/CT imaging after intravenous injection of 18F-FDG(5.55 MBq/kg). MIMneuro software was used to analyze the data. The correlation between the CGM and cognitive function was analyzed using Pearson or Spearman correlation analysis. Results (1) Compared with NC group, PDD group presented a widespread cortical metabolism decrease in frontal, parietal, temporal, occipital lobes and the limbic lobe; PD-MCI group showed hypometabolic areas in the parietal and occipital lobes, and with less extent in the frontal and temporal lobes; PD-NC group showed no significant cerebral hypometabolism. (2) Compared with PD-NC group, PDD group showed widespread cortical metabolism decrease in occipital lobe, temporal lobe, partial parietal cortex and the posterior cingulated cortex. Compared with PD-MCI group, PDD group had lower metabolism, mainly in posterior brain areas (parietal, occipital and temporal lobes). Compared with PD-NC group, PD-MCI group showed hypometabolism in right supramarginal gyrus and the left parahippocampal gyrus. (3) There were positive correlations between visuospatial/executive function and visual cortex metabolism, angular gyrus metabolism or superior parietal lobule metabolism (r=0.535, 0.443, 0.395; all P<0.05). A positive correlation was also found between delayed memory and heschl's gyrus metabolism (r=0.337, P<0.05). Conclusions The cerebral glucose metabolism detected with 18F-FDG PET/CT is well correlated with MOCA assessments. Thus it may be helpful in evaluation of the progress of cognitive impairments in PD. Key words: Parkinson disease; Cognition disorders; Tomography, emission-computed; Tomography, X-ray computed; Deoxyglucose