title: Mapping track density changes in nigrostriatal and extranigral pathways in Parkinson's disease.
abstract: In Parkinson's disease (PD) the demonstration of neuropathological disturbances in nigrostriatal and extranigral brain pathways using magnetic resonance imaging remains a challenge. Here, we applied a novel diffusion-weighted imaging approach-track density imaging (TDI). Twenty-seven non-demented Parkinson's patients (mean disease duration: 5 years, mean score on the Hoehn & Yahr scale=1.5) were compared with 26 elderly controls matched for age, sex, and education level. Track density images were created by sampling each subject's spatially normalized fiber tracks in 1mm isotropic intervals and counting the fibers that passed through each voxel. Whole-brain voxel-based analysis was performed and significance was assessed with permutation testing. Statistically significant increases in track density were found in the Parkinson's patients, relative to controls. Clusters were distributed in disease-relevant areas including motor, cognitive, and limbic networks. From the lower medulla to the diencephalon and striatum, clusters encompassed the known location of the locus coeruleus and pedunculopontine nucleus in the pons, and from the substantia nigra up to medial aspects of the posterior putamen, bilaterally. The results identified in brainstem and nigrostriatal pathways show a large overlap with the known distribution of neuropathological changes in non-demented PD patients. Our results also support an early involvement of limbic and cognitive networks in Parkinson's disease.
authors: Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Erik
authors: E
authors: Ziegler
authors: MoVeRe Group, Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Maud
authors: M
authors: Rouillard
authors: Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Elodie
authors: E
authors: André
authors: MoVeRe Group, Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Tim
authors: T
authors: Coolen
authors: Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Johan
authors: J
authors: Stender
authors: Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Evelyne
authors: E
authors: Balteau
authors: Cyclotron Research Centre, University of Liège, Liège, Belgium; Department of Electrical Engineering and Computer Science, University of Liège, Liège, Belgium. Electronic address: c.phillips@ulg.ac.be.
authors: Christophe
authors: C
authors: Phillips
authors: MoVeRe Group, Cyclotron Research Centre, University of Liège, Liège, Belgium; Department of Neurology, University of Liège, Liège, Belgium.
authors: Gaëtan
authors: G
authors: Garraux
mesh_terms: D000368:Aged; D001933:Brain Stem / Q000473:pathology; D003071:Cognition; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008032:Limbic System / Q000473:pathology; D008297:Male; D008875:Middle Aged; D017072:Neostriatum / Q000473:pathology*; D009434:Neural Pathways / Q000473:pathology*; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000473:pathology* / Q000523:psychology; D013378:Substantia Nigra / Q000473:pathology*
keywords: Diffusion; Parkinson's disease; Substantia nigra; Tractography; White matter