title: Non-uniformly weighted sampling for faster localized two-dimensional correlated spectroscopy of the brain in vivo.
abstract: Two-dimensional localized correlated spectroscopy (2D L-COSY) offers greater spectral dispersion than conventional one-dimensional (1D) MRS techniques, yet long acquisition times and limited post-processing support have slowed its clinical adoption. Improving acquisition efficiency and developing versatile post-processing techniques can bolster the clinical viability of 2D MRS. The purpose of this study was to implement a non-uniformly weighted sampling (NUWS) scheme for faster acquisition of 2D-MRS. A NUWS 2D L-COSY sequence was developed for 7T whole-body MRI. A phantom containing metabolites commonly observed in the brain at physiological concentrations was scanned ten times with both the NUWS scheme of 12:48 duration and a 17:04 constant eight-average sequence using a 32-channel head coil. 2D L-COSY spectra were also acquired from the occipital lobe of four healthy volunteers using both the proposed NUWS and the conventional uniformly-averaged L-COSY sequence. The NUWS 2D L-COSY sequence facilitated 25% shorter acquisition time while maintaining comparable SNR in humans (+0.3%) and phantom studies (+6.0%) compared to uniform averaging. NUWS schemes successfully demonstrated improved efficiency of L-COSY, by facilitating a reduction in scan time without affecting signal quality.
authors.affiliation: Radiology, B6 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104, United States.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Verma
authors.affiliation: Radiology, B6 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104, United States.
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Chawla
authors.affiliation: Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, United States.
authors.forename: Rajakumar
authors.initials: R
authors.lastname: Nagarajan
authors.affiliation: Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, United States.
authors.forename: Zohaib
authors.initials: Z
authors.lastname: Iqbal
authors.affiliation: Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, United States. Electronic address: athomas@ucla.edu.
authors.forename: M
authors.initials: M
authors.lastname: Albert Thomas
authors.affiliation: Radiology, B6 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104, United States. Electronic address: harish.poptani@liverpool.ac.uk.
authors.forename: Harish
authors.initials: H
authors.lastname: Poptani
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging*; D001923:Brain Chemistry; D003198:Computer Simulation; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio
keywords: Coil Combination; Localized correlated spectroscopy (L-COSY); Magnetic resonance spectroscopy (MRS); NAA, Cr, Ch, GSH, GABA; Non-uniformly weighted sampling; Two-dimensional L-COSY; Uniformly averaged