Voxel-based comparison of regional cerebral glucose metabolism between PSP and corticobasal degeneration

OBJECTIVES Progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) are neurodegenerative disorders that may be accompanied by dementia and parkinsonism as clinical symptoms. The purpose of this study was to elucidate cerebral metabolic differences of these two diseases with cognitive impairments by [18F] fluorodeoxyglucose (FDG) and positron emission tomography (PET). METHODS A total of 12 patients with PSP (age: 62.8+/-6.0 years old, m: 7, f: 5, Mini-Mental State Examination (MMSE): 23.4+/-2.6), 12 patients with CBD (age: 64.8+/-6.3 years old, m: 6, f: 6, MMSE: 22.9+/-4.5), and age-matched healthy subjects (normal control (NC)) (age: 63.8+/-7.7 years old, m: 7, f: 5) were subjected to FDG-PET to obtain glucose metabolic images. We compared regional cerebral metabolic images by a voxel-by-voxel analysis with statistical parametric mapping (SPM) among PSP, CBD, and NC subjects, and evaluated differences of hypometabolic regions. RESULTS The patients with PSP showed reduced cerebral glucose metabolism in the medial and lateral frontal gyri, basal ganglia, and midbrain compared with NC, whereas the patients with CBD showed significant reduction in the parietal lobes (p<0.001). SPM also revealed parietal hypometabolism in CBD patients compared with PSP patients (p<0.001). CONCLUSIONS The predominant parietal glucose metabolic reduction in CBD patients was different from previously reported findings. This finding would be the characteristic substance of patients with CBD accompanying cognitive impairments. Our findings suggest that measurement of glucose metabolism by PET and a voxel-based analysis is useful to understand the pathophysiology of these two diseases with cognitive impairments.