title: Mapping glutamate in subcortical brain structures using high-resolution GluCEST MRI.
abstract: In vivo measurement of glutamate (Glu) in brain subcortex can elucidate the role these structures play in cognition and neuropsychiatric disorders. However, accurate quantification of Glu in subcortical regions is challenging. Recently, a novel MRI method based on the Glu chemical exchange saturation transfer (GluCEST) effect has been developed for detecting brain Glu in millimolar concentrations. Here, we use GluCEST to map Glu distributions in subcortical structures of the human brain (e.g. amygdala, hippocampus). Overall, GluCEST was ~40% higher in gray matter than in white matter. Within the subcortical gray matters, amygdala showed the highest GluCEST contrast. Utilizing MR spectroscopic data, in vivo GluCEST detection sensitivity (~0.8% mM(-1) ) in subcortical gray matter was evaluated and was consistent with the previously reported values. In general, the GluCEST map approximates the Glu receptor distribution reported in previous positron emission tomography (PET) studies. These findings suggest that high-resolution GluCEST MRI of subcortical brain structures may prove to be a useful tool in diagnosis of brain disorders or treatment responses.
authors.affiliation: University of Pennsylvania, Radiology, Philadelphia, PA, USA.
authors.forename: Kejia
authors.initials: K
authors.lastname: Cai
authors.forename: Anup
authors.initials: A
authors.lastname: Singh
authors.forename: David R
authors.initials: DR
authors.lastname: Roalf
authors.forename: Ravi Prakash Reddy
authors.initials: RP
authors.lastname: Nanga
authors.forename: Mohammad
authors.initials: M
authors.lastname: Haris
authors.forename: Hari
authors.initials: H
authors.lastname: Hariharan
authors.forename: Ruben
authors.initials: R
authors.lastname: Gur
authors.forename: Ravinder
authors.initials: R
authors.lastname: Reddy
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D055815:Young Adult
chemical_list: D018698:Glutamic Acid
keywords: amygdala; chemical exchange saturation transfer (CEST); glutamate; magnetic resonance spectroscopy (MRS); subcortical brain structures
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