Proton MRS of the unilateral substantia nigra in the human brain at 4 tesla: detection of high GABA concentrations.
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.
Oz
Gülin
G
Center for MR Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455, USA. gulin@cmrr.umn.edu
Terpstra
Melissa
M
Tkác
Ivan
I
Aia
Pratibha
P
Lowary
Jodi
J
Tuite
Paul J
PJ
Gruetter
Rolf
R
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*
D011522:Protons; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; C000179:N-acetylaspartate; D005978:Glutathione