Fig. 2.

Disease-related spatial covariance patterns. (A) Parkinson disease-related pattern (PDRP) identified by spatial covariance analysis of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) scans from 33 patients with Parkinson disease and 33 age-matched normal volunteer subjects. This pattern was characterized by relative metabolic increases (red) in the pallidum and thalamus, in the pons and cerebellum, and in the sensorimotor cortex. These changes covaried with metabolic decreases (blue) in the lateral premotor cortex and in parieto-occipital association regions. (Adapted from Ma et al. Abnormal metabolic network activity in Parkinson’s disease: test-rest reproducibility. J Cereb Blood Flow Metab 2007;27:597–605.) (B) Multiple system atrophy-related pattern (MSARP) identified by spatial covariance analysis of FDG PET scans from 10 patients with multiple system atrophy and 10 healthy controls. This pattern was characterized by covarying metabolic decreases (blue) in the putamen and the cerebellum. (Adapted with permission from Eckert et al. Abnormal Metabolic Networks in Atypical Parkinsonism. Mov Disord 2008;23:727–733.) (C) Progressive supranuclear palsy-related pattern (PSPRP) identified by spatial covariance analysis of FDG PET scans from 10 patients with progressive supranuclear palsy and 10 healthy controls. This pattern was characterized by covarying metabolic decreases (blue) in the medial prefrontal cortex, the frontal eye fields, the ventrolateral prefrontal cortex, the caudate nuclei, the medial thalamus, and the upper brainstem. (Adapted with permission from Eckert et al. Abnormal Metabolic Networks in Atypical Parkinsonism. Mov Disord 2008;23:727–733.) (The covariance maps were overlaid on T1-weighted magnetic resonance-template images. Voxels with positive region weights [metabolic increases] are color-coded red and those with negative region weights [metabolic decreases] are color-coded blue.)