title: 3D GABA imaging with real-time motion correction, shim update and reacquisition of adiabatic spiral MRSI.
abstract: Gamma-aminobutyric acid (GABA) and glutamate (Glu) are the major neurotransmitters in the brain. They are crucial for the functioning of healthy brain and their alteration is a major mechanism in the pathophysiology of many neuro-psychiatric disorders. Magnetic resonance spectroscopy (MRS) is the only way to measure GABA and Glu non-invasively in vivo. GABA detection is particularly challenging and requires special MRS techniques. The most popular is MEscher-GArwood (MEGA) difference editing with single-voxel Point RESolved Spectroscopy (PRESS) localization. This technique has three major limitations: a) MEGA editing is a subtraction technique, hence is very sensitive to scanner instabilities and motion artifacts. b) PRESS is prone to localization errors at high fields (≥3T) that compromise accurate quantification. c) Single-voxel spectroscopy can (similar to a biopsy) only probe steady GABA and Glu levels in a single location at a time. To mitigate these problems, we implemented a 3D MEGA-editing MRS imaging sequence with the following three features: a) Real-time motion correction, dynamic shim updates, and selective reacquisition to eliminate subtraction artifacts due to scanner instabilities and subject motion. b) Localization by Adiabatic SElective Refocusing (LASER) to improve the localization accuracy and signal-to-noise ratio. c) K-space encoding via a weighted stack of spirals provides 3D metabolic mapping with flexible scan times. Simulations, phantom and in vivo experiments prove that our MEGA-LASER sequence enables 3D mapping of GABA+ and Glx (Glutamate+Gluatmine), by providing 1.66 times larger signal for the 3.02ppm multiplet of GABA+ compared to MEGA-PRESS, leading to clinically feasible scan times for 3D brain imaging. Hence, our sequence allows accurate and robust 3D-mapping of brain GABA+ and Glx levels to be performed at clinical 3T MR scanners for use in neuroscience and clinical applications.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; MRCE, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bogner
authors.affiliation: Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Borjan
authors.initials: B
authors.lastname: Gagoski
authors.affiliation: Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford Centre for Clinical Magnetic Resonance Research, Oxford, UK.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Hess
authors.affiliation: Siemens Healthcare, Charlestown, MA, USA.
authors.forename: Himanshu
authors.initials: H
authors.lastname: Bhat
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: M Dylan
authors.initials: MD
authors.lastname: Tisdall
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Andre J W
authors.initials: AJW
authors.lastname: van der Kouwe
authors.affiliation: MRCE, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Strasser
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Marjańska
authors.affiliation: MRCE, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.affiliation: Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Ellen
authors.initials: E
authors.lastname: Grant
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Rosen
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: ovidiu@nmr.mgh.harvard.edu.
authors.forename: Ovidiu C
authors.initials: OC
authors.lastname: Andronesi
mesh_terms: D000328:Adult; D016477:Artifacts; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D012815:Signal Processing, Computer-Assisted; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
chemical_list: D005680:gamma-Aminobutyric Acid
keywords: Frequency drift correction; GABA; Glutamate; LASER; MEGA editing; Magnetic resonance spectroscopy; Neurotransmitter; Prospective motion correction; Reacquisition; Real-time correction; Spiral imaging