title: In vivo detection of lateral-ventral tier nigral degeneration in Parkinson's disease.
abstract: The objective of this study was to measure neuromelanin-sensitive MRI contrast changes in the lateral-ventral tier of substantia nigra pars compacta in Parkinson's disease (PD). Histopathological studies of PD have demonstrated both massive loss of melanized dopamine neurons and iron accumulation in the substantia nigra pars compacta. Neurodegeneration is most profound in the lateral-ventral tier of this structure. We have previously shown in both healthy controls and individuals with PD that neuromelanin-sensitive MRI and iron-sensitive MRI contrast regions in substantia nigra overlap. This overlap region is located in the lateral-ventral tier. Exploiting this area of contrast overlap for region of interest selection, we developed a semi-automated image processing approach to characterize the lateral-ventral tier in MRI data. Here we apply this approach to measure magnetization transfer contrast, which corresponds to local neuromelanin density, in both the lateral-ventral tier and the entire pars compacta in 22 PD patients and 19 controls. Significant contrast reductions were seen in PD in both the entire pars compacta (P = 0.009) and in its lateral-ventral tier (P = 0.0002); in PD contrast was significantly lower in the lateral-ventral tier than in the entire pars compacta (P = 0.0008). These findings are the first in vivo evidence of the selective vulnerability of this nigral subregion in PD, and this approach may be developed for high impact biomarker applications. Hum Brain Mapp 38:2627-2634, 2017. © 2017 Wiley Periodicals, Inc.
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Daniel E
authors.identifier: 0000-0003-0503-3736
authors.initials: DE
authors.lastname: Huddleston
authors.affiliation: Center for Advanced Neuroimaging, University of California Riverside, Riverside, California.
authors.forename: Jason
authors.identifier: 0000-0001-9412-1265
authors.initials: J
authors.lastname: Langley
authors.affiliation: Department of Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Sedlacik
authors.affiliation: Department of Neurology, Julius-Maximilians University, Würzburg, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Boelmans
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Stewart A
authors.initials: SA
authors.lastname: Factor
authors.affiliation: Department of Bioengineering, University of California Riverside, Riverside, California.
authors.forename: Xiaoping P
authors.initials: XP
authors.lastname: Hu
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000209:etiology* / Q000473:pathology*; D010300:Parkinson Disease / Q000150:complications*; D012372:ROC Curve; D012720:Severity of Illness Index; D013378:Substantia Nigra / Q000000981:diagnostic imaging / Q000473:pathology*; D011795:Surveys and Questionnaires
keywords: MRI; biomarkers; dopaminergic neurons; humans; image processing; iron; neuromelanin; pars compacta; substantia nigra