title: Proton MRS of the unilateral substantia nigra in the human brain at 4 tesla: detection of high GABA concentrations.
abstract: Parkinson's disease (PD) is characterized by loss of dopaminergic neurons in the substantia nigra (SN), the cause of which is unknown. Characterization of early SN pathology could prove beneficial in the treatment and diagnosis of PD. The present study shows that with the use of short-echo (5 ms) Stimulated-Echo Acquisition Mode (STEAM) spectroscopy and LCModel, a neurochemical profile consisting of 10 metabolites, including gamma-aminobutyric acid (GABA), glutamate (Glu), and glutathione (GSH), can be measured from the unilateral SN at 4 tesla. The neurochemical profile of the SN is unique and characterized by a fourfold higher GABA/Glu ratio compared to the cortex, in excellent agreement with established neurochemistry. The presence of elevated GABA levels in SN was validated with the use of editing, suggesting that partial volume effects were greatly reduced. These findings establish the feasibility of obtaining a neurochemical profile of the unilateral human SN by single-voxel spectroscopy in small volumes.
authors.affiliation: Center for MR Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455, USA. gulin@cmrr.umn.edu
authors.forename: Gülin
authors.initials: G
authors.lastname: Oz
authors.forename: Melissa
authors.initials: M
authors.lastname: Terpstra
authors.forename: Ivan
authors.initials: I
authors.lastname: Tkác
authors.forename: Pratibha
authors.initials: P
authors.lastname: Aia
authors.forename: Jodi
authors.initials: J
authors.lastname: Lowary
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Tuite
authors.forename: Rolf
authors.initials: R
authors.lastname: Gruetter
mesh_terms: D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D005240:Feasibility Studies; D018698:Glutamic Acid / Q000378:metabolism; D005978:Glutathione / Q000737:chemistry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010300:Parkinson Disease / Q000378:metabolism*; D011522:Protons; D013378:Substantia Nigra / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D011522:Protons; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; C000179:N-acetylaspartate; D005978:Glutathione