Glucose metabolism in small subcortical structures in Parkinson’s disease
Abstract:Objectives – Evidence from experimental animal models of Parkinson’s disease (PD) suggests a characteristic pattern of metabolic perturbation in discrete, very small basal ganglia structures. These structures are generally too small to allow valid investigation by conventional positron emission tomography (PET) cameras. However, the high‐resolution research tomograph (HRRT) PET system has a resolution of 2 mm, sufficient for the investigation of important structures such as the pallidum and thalamic subnuclei.
Materials and methods – Using the HRRT, we performed [18F]‐fluorodeoxyglucose (FDG) scans on 21 patients with PD and 11 age‐matched controls. We employed three types of normalization: white matter, global mean, and data‐driven normalization. We performed volume‐of‐interest analyses of small subcortical gray matter structures. Voxel‐based comparisons were performed to investigate the extent of cortical hypometabolism.
Results – The most significant level of relative subcortical hypermetabolism was detected in the external pallidum (GPe), irrespective of normalization strategy. Hypermetabolism was suggested also in the internal pallidum, thalamic subnuclei, and the putamen. Widespread cortical hypometabolism was seen in a pattern very similar to previously reported patterns in patients with PD.
Conclusion – The presence and extent of subcortical hypermetabolism in PD is dependent on type of normalization. However, the present findings suggest that PD, in addition to widespread cortical hypometabolism, is probably characterized by true hypermetabolism in the GPe. This finding was predicted by the animal 2‐deoxyglucose autoradiography literature, in which high‐magnitude hypermetabolism was also most robustly detected in the GPe.
Document Type: Research Article
Affiliations: 1: PET Centre, Aarhus University Hospitals, Aarhus, Denmark 2: Department of Neurology, University of Cologne, Cologne, Germany 3: Rotman Research Institute, Baycrest Hospital and Mouse Imaging Center, Hospital for Sick Children, Toronto, ON, Canada 4: Department of Neurology, University of Frankfurt, Frankfurt, Germany 5: Max-Planck Institute for Neurological Research, Cologne, Germany 6: Brain Imaging Center, University of California, Irvine, CA, USA
Publication date: 2012-05-01