PURPOSE: To compare the repeatability of γ-aminobutyric acid (GABA) measurements using J-difference editing, before and after spectral realignment-a technique which has previously been demonstrated to improve the quality of J-difference GABA spectra. MATERIALS AND METHODS: We performed in vivo measurements in three brain regions (occipital, sensorimotor, and dorsolateral prefrontal cortex [DLPFC]), and analyzed these using alternative alignment approaches to evaluate the impact of alignment on repeatability: "Independent alignment" (aligning each subspectrum independently) and "Pairwise alignment" (aligning each on and off subspectrum as a pair) were compared. RESULTS: Pairwise alignment improved the group mean coefficient of variation in all regions; 0.4% in occipital, 1.1% in sensorimotor, and 1.1% in DLPFC. Independent alignment resulted in subtraction artifacts in the majority of cases, and increased the coefficient of variation in the DLPFC by 9.4%. Simulations demonstrate that the GABA quantification error in datasets with high B0 drift, is 4.5% without alignment, but <1% with optimal alignment. CONCLUSION: Pairwise alignment improves the repeatability of GABA spectroscopy data. However, independently aligning all on and off subspectra can lead to artifacts and worse repeatability when compared with nonaligned data.
PURPOSE: To compare the repeatability of γ-aminobutyric acid (GABA) measurements using J-difference editing, before and after spectral realignment-a technique which has previously been demonstrated to improve the quality of J-difference GABA spectra. MATERIALS AND METHODS: We performed in vivo measurements in three brain regions (occipital, sensorimotor, and dorsolateral prefrontal cortex [DLPFC]), and analyzed these using alternative alignment approaches to evaluate the impact of alignment on repeatability: "Independent alignment" (aligning each subspectrum independently) and "Pairwise alignment" (aligning each on and off subspectrum as a pair) were compared. RESULTS: Pairwise alignment improved the group mean coefficient of variation in all regions; 0.4% in occipital, 1.1% in sensorimotor, and 1.1% in DLPFC. Independent alignment resulted in subtraction artifacts in the majority of cases, and increased the coefficient of variation in the DLPFC by 9.4%. Simulations demonstrate that the GABA quantification error in datasets with high B0 drift, is 4.5% without alignment, but <1% with optimal alignment. CONCLUSION: Pairwise alignment improves the repeatability of GABA spectroscopy data. However, independently aligning all on and off subspectra can lead to artifacts and worse repeatability when compared with nonaligned data.
Authors: Nicolaas A J Puts; Ashley D Harris; Deana Crocetti; Carrie Nettles; Harvey S Singer; Mark Tommerdahl; Richard A E Edden; Stewart H Mostofsky Journal: J Neurophysiol Date: 2015-06-03 Impact factor: 2.714
Authors: Ashley D Harris; Benjamin Glaubitz; Jamie Near; C John Evans; Nicolaas A J Puts; Tobias Schmidt-Wilcke; Martin Tegenthoff; Peter B Barker; Richard A E Edden Journal: Magn Reson Med Date: 2013-11-11 Impact factor: 4.668
Authors: Eva Heckova; Michal Považan; Bernhard Strasser; Patrik Krumpolec; Petra Hnilicová; Gilbert J Hangel; Philipp A Moser; Ovidiu C Andronesi; Andre J van der Kouwe; Peter Valkovic; Barbara Ukropcova; Siegfried Trattnig; Wolfgang Bogner Journal: Radiology Date: 2017-09-28 Impact factor: 11.105
Authors: Mark Mikkelsen; Muhammad G Saleh; Jamie Near; Kimberly L Chan; Tao Gong; Ashley D Harris; Georg Oeltzschner; Nicolaas A J Puts; Kim M Cecil; Iain D Wilkinson; Richard A E Edden Journal: Magn Reson Med Date: 2017-12-07 Impact factor: 4.668
Authors: Paul G Mullins; David J McGonigle; Ruth L O'Gorman; Nicolaas A J Puts; Rishma Vidyasagar; C John Evans; Richard A E Edden Journal: Neuroimage Date: 2012-12-13 Impact factor: 6.556
Authors: Ricardo C G Landim; Richard A E Edden; Bernd Foerster; Li Min Li; Roberto J M Covolan; Gabriela Castellano Journal: Magn Reson Imaging Date: 2015-12-02 Impact factor: 2.546