title: Volumetric navigated MEGA-SPECIAL for real-time motion and shim corrected GABA editing.
abstract: Mescher-Garwood (MEGA) editing with spin echo full intensity acquired localization (MEGA-SPECIAL, MSpc) is a technique to acquire γ-aminobutyric acid (GABA) without macromolecule (MM) contamination at a TE of 68 ms. However, due to the requirement of multiple shot-localization, it is often susceptible to subject motion and B0 inhomogeneity. A method is presented for real-time shim and motion correction (ShMoCo) using volumetric navigators to correct for motion and motion-related B0 inhomogeneity during MSpc acquisition. A phantom experiment demonstrates that ShMoCo restores the GABA peak and improves spectral quality in the presence of motion and zero- and first-order shim changes. The ShMoCo scans were validated in three subjects who performed up-down and left-right head rotations. Qualitative assessment of these scans indicates effective reduction of subtraction artefacts and well edited GABA peaks, while quantitative analysis indicates superior fitting and spectral quality relative to scans with no correction. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Department of Human Biology, MRC/UCT Medical Imaging Research Unit, University of Cape Town, Cape Town, Western Cape, South Africa.
authors.forename: Muhammad G
authors.initials: MG
authors.lastname: Saleh
authors.affiliation: Department of Human Biology, MRC/UCT Medical Imaging Research Unit, University of Cape Town, Cape Town, Western Cape, South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Alhamud
authors.affiliation: Douglas Mental Health University Institute and Department of Psychiatry, McGill University, Montreal, Canada.
authors.forename: Jamie
authors.initials: J
authors.lastname: Near
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, United States.
authors.forename: André J W
authors.initials: AJ
authors.lastname: van der Kouwe
authors.affiliation: Department of Human Biology, MRC/UCT Medical Imaging Research Unit, University of Cape Town, Cape Town, Western Cape, South Africa.
authors.forename: Ernesta M
authors.initials: EM
authors.lastname: Meintjes
mesh_terms: D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging; D013113:Spin Labels; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D013113:Spin Labels; D005680:gamma-Aminobutyric Acid
keywords: GABA; MEGA-SPECIAL; edited spectrum; first-order shim term; prospective correction; real-time motion correction; real-time shim correction; zero-order shim term