Proton MR Spectroscopy of Substantia Nigra in the Human Brain at 4 Tesla: Measurement of High GABA Concentrations

Introduction Parkinson’s disease (PD) is characterized by loss of dopaminergic neurons in the substantia nigra (SN), but its etiology remains poorly understood (1). In vivo H MRS may provide a noninvasive alternative to culture, animal model and post-mortem studies that are more commonly utilized to understand the pathogenesis of PD. However, due to its small size, the MRS investigation of the SN in the human brain is difficult (2). Previous studies primarily employed 6-8ml voxels which implicate substantial partial volume effects. In addition, they were performed at 1.5 Tesla and therefore only provided data on NAA, creatine, choline and their respective ratios (2). The aim of the current study was to determine the feasibility of expanding the information content of H MR spectra from smaller volumes at 4 Tesla to neurotransmitters, such as GABA and glutamate, and the antioxidant glutathione.