Jim Murdoch - Academia.edu (original) (raw)
Papers by Jim Murdoch
Journal of the American Chemical Society, Jun 1, 1981
The method of total spin coherence transfer echo spectroscopy is introduced and shown to give.hig... more The method of total spin coherence transfer echo spectroscopy is introduced and shown to give.high resolution NMR spectra free of broadening due to magnet inhomogeneity. A single quantum proton spectrum of oriented aceta 1 de hyde_ demor}s~ra te~_ ~t!_e. . te~h_n_i que.__. Comparison with other spin echo techniques is made and applications to multiple quantum NMR are discussed.
This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention ... more This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention copy, call l. ~.Info~ ~ivision, Ext. 6782~-All
Chemischer Informationsdienst, Sep 29, 1981
The homogeneity of the static magnetic field is the most common limitation on the resolution of N... more The homogeneity of the static magnetic field is the most common limitation on the resolution of N M R spectra, and a variety of spin echo techniques have been devised to extract high-resolution information from inhomogeneously broadened samples.'+ In this 6-Silafulvene via Silylcarbene Rearrangement from Diazo-2-silacyclohexa-3,5-diene
Target audience: Scientists and clinicians who are interested in the in vivo measurement of gluta... more Target audience: Scientists and clinicians who are interested in the in vivo measurement of glutamate (Glu), glutamine (Gln), and glutathione (GSH) using magnetic resonance spectroscopy (MRS). Purpose: Glu and Gln play important roles in brain chemical and neurobiological processes. Accurate measurement of Glu and Gln using in vivo MRS is hampered by spectral overlap. A TE-optimized PRESS (point-resolved spectroscopy) pulse sequence has been proposed to resolve and measure Glu and Gln at 7T (1). In this study, we optimized the TE values of the pulse sequence, validated the numerical simulations through phantom experiments, and performed MRS scans on eight healthy volunteers for in vivo quantification of glutamate, glutamine and other metabolites such as GSH. Methods: Pulse sequence optimization: The pulse sequence consists of PRESS localization with a J-suppression RF pulse inserted at the midpoint between the two refocusing pulses. The J-suppression pulse is a frequency selective s...
Target audience: Scientists and clinicians who are interested in measuring glutamate (Glu) and gl... more Target audience: Scientists and clinicians who are interested in measuring glutamate (Glu) and glutamine (Gln) using magnetic resonance spectroscopy (MRS). Purpose: In vivo measurements of Glu and Gln in the human brain are important for studying many neurological and psychiatric diseases because Glu is a vital link between brain energy metabolism and glutamatergic neurotransmission. Spectral separation of glutamate, glutamine, and other coupled spins at 3T is difficult. Recently, Choi et al. [1] proposed to use a TE optimized PRESS (point-resolved spectroscopy) method at 7T to resolve glutamate and glutamine, taking advantage of the chemical shift offset artifact [2,3] to suppress overlapping signals from the aspartyl moiety of NAA. In this work, we propose to suppress spectral interference from the aspartyl moiety of NAA by a selective RF pulse placed at the resonance frequency of the NAA aspartyl CH proton at 4.38 ppm, which alters the J-evolution of the NAA aspartyl CH2 multiple...
Edited MRS sequences are widely used for studying GABA in the human brain. Several algorithms are... more Edited MRS sequences are widely used for studying GABA in the human brain. Several algorithms are available for modelling these data, deriving metabolite concentration estimates through peak fitting or a linear combination of basis spectra. The present study compares seven such algorithms, using data obtained in a large multi-site study.GABA-edited (GABA+, TE = 68 ms MEGA-PRESS) data from 222 subjects at 20 sites were processed via a standardised pipeline, before modelling with FSL-MRS, Gannet, AMARES, QUEST, LCModel, Osprey and Tarquin, using standardised vendor-specific basis sets (for GE, Philips and Siemens) where appropriate.After referencing metabolite estimates (to water or creatine), systematic differences in scale were observed between datasets acquired on different vendors’ hardware, presenting across algorithms. Scale differences across algorithms were also observed.Using the correlation between metabolite estimates and voxel tissue fraction as a benchmark, most algorithm...
Lawrence Berkeley Lab Nucl Waste Isolation Geophys and Reservoir Eng Geosci, Aug 30, 1982
Introduction GABA detection faces the problem of contamination from co-edited macromolecule signa... more Introduction GABA detection faces the problem of contamination from co-edited macromolecule signal at 3.0 ppm (MM30) when using the MEGA-PRESS technique [1]. Therefore, direct quantification of GABA by LCModel software [2] yields the sum of GABA and MM30. One of the proposed methods to eliminate MM30 is to alternate the editing pulse between 1.9 ppm and 1.5 ppm, the latter a position symmetric to 1.9 ppm with respect to the J-coupled MM resonance at 1.7 ppm [3]. New MM basis have also been introduced into LCModel analysis [4], and a soft constraint has been applied to better quantify GABA [5]. In this study, we compare three LCModel fitting approaches for both the original MEGA-PRESS and the modified “MM-symmetric” sequence which has the editing pulse alternating between 1.9 ppm and 1.5 ppm.
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2007
Ziele: Spektroskopische Bildgebung (SI: Spectroscopic Imaging oder CSI: Chemical Shift Imaging) w... more Ziele: Spektroskopische Bildgebung (SI: Spectroscopic Imaging oder CSI: Chemical Shift Imaging) wird in der Magnet-Resonanz-Spektroskopie genutzt, um lokale Konzentrationsanderungen von Metaboliten in-vivo aufzuspuren. Die raumliche Position wird phasenkodiert, und ein Spektrum wird nach jedem Phasenkodierschritt aufgenommen, um somit im Gesamtvolumen die Spektren von vielen Teilvolumina (Voxel) aufzunehmen. Diese Studie untersucht SI des menschlichen Gehirns bei ultra-hohen Magnetfeldstarken und zeigt Losungswege, Magnetfeldinhomogenitaten und Suszeptibilitatsartefakte zu verringern. Methode: Spektrokopische Bildgebung des menschlichen Gehirns wurde an 7 Probanden in einem 7T Gankorper-MR-Tomographen (Philips Medical Systems) mit einer Sende/Empfangs-Kopfspule durchgefuhrt. Transversale Spin-Echo-Schichtlokalisation wurde mit den folgenden Parametern TR=1500ms, TE=144ms, Field of View=250mm, 28×28 Matrix, Schichtdicke=20mm und NEX=1 durchgefuhrt. SI wurde in einem Probanden zusatzlich mit einer kurzen Echozeit TE=26ms untersucht. Ergebnis: Hochaufgeloste MR-Spektren konnten im Gehirn aller Probanden aufgenommen werden. Die Resonanzen von Cholin, Creatin, N-Acetylaspartat und Myoinositol wurden in allen SI-Voxeln des Gehirns identifiziert. SI mit kurzer Echozeit loste zusatzlich die Resonanzen von Glutamate, Glutamine und Scylloinositol auf. Schlussfolgerung: SI ist bei ultrahohen Magnetfeldstarken moglich und erhoht die Sensitivitat und die spektrale Auflosung in der Magnet-Resonanz-Spektroskopie. Eine PRESS-Lokalisation ist aufgrund der Chemical-Shift-Verschiebung bei ultra-hohen Feldern nicht praktikabel, stattdessen ist eine Spin-Echo Schichtlokalisation zu bevorzugen. Ein Shim zweiter Ordnung minimiert die Linieverbreiterung der Spektrallinien, die durch starke Suszeptiblitatseffekte bei hohen Magnetfeldstarken hervorgerufen werden. Ultrahochfeld SI verbessert die nicht-invasive Charakterisierung und Quantifizierung von molekularen Markern bei einer Vielzahl neurologischer Erkrankungen. Korrespondierender Autor: Sammet S The Ohio State University, Department of Radiology, 1654 Upham Drive, 43210 Columbus E-Mail: sammet.5@osu.edu
Sports Medicine, 2021
Muscle fibre typology as a novel risk factor for hamstring strain injuries in professional footba... more Muscle fibre typology as a novel risk factor for hamstring strain injuries in professional football (soccer): a prospective cohort study RUNNING HEAD:
American Journal of Neuroradiology, 2010
is an established noninvasive MR imaging technique that can be helpful in the diagnosis of brain ... more is an established noninvasive MR imaging technique that can be helpful in the diagnosis of brain lesions and in treatment planning. Claustrophobia and body habitus preclude some patients from routine MR imaging in a closed-bore system. The development of 1 H-MR spectroscopy for use in an open MR imaging system would enable a more complete characterization of brain lesions in these patients. ABBREVIATIONS: CH 2 ϭ methyl; Cho ϭ choline; Cr ϭ creatine; FLAIR ϭ fluid-attenuated inversion recovery; 1 H-MR spectroscopy ϭ proton MR spectroscopy; NAA ϭ N-acetylaspartate; PML ϭ progressive multifocal leukoencephalopathy; PRESS ϭ point-resolved spectroscopic sequence; SNR ϭ signal-to-noise ratio; SVS ϭ single-voxel spectroscopy
Journal of the American Chemical Society, Jun 1, 1981
The method of total spin coherence transfer echo spectroscopy is introduced and shown to give.hig... more The method of total spin coherence transfer echo spectroscopy is introduced and shown to give.high resolution NMR spectra free of broadening due to magnet inhomogeneity. A single quantum proton spectrum of oriented aceta 1 de hyde_ demor}s~ra te~_ ~t!_e. . te~h_n_i que.__. Comparison with other spin echo techniques is made and applications to multiple quantum NMR are discussed.
This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention ... more This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention copy, call l. ~.Info~ ~ivision, Ext. 6782~-All
Chemischer Informationsdienst, Sep 29, 1981
The homogeneity of the static magnetic field is the most common limitation on the resolution of N... more The homogeneity of the static magnetic field is the most common limitation on the resolution of N M R spectra, and a variety of spin echo techniques have been devised to extract high-resolution information from inhomogeneously broadened samples.'+ In this 6-Silafulvene via Silylcarbene Rearrangement from Diazo-2-silacyclohexa-3,5-diene
Target audience: Scientists and clinicians who are interested in the in vivo measurement of gluta... more Target audience: Scientists and clinicians who are interested in the in vivo measurement of glutamate (Glu), glutamine (Gln), and glutathione (GSH) using magnetic resonance spectroscopy (MRS). Purpose: Glu and Gln play important roles in brain chemical and neurobiological processes. Accurate measurement of Glu and Gln using in vivo MRS is hampered by spectral overlap. A TE-optimized PRESS (point-resolved spectroscopy) pulse sequence has been proposed to resolve and measure Glu and Gln at 7T (1). In this study, we optimized the TE values of the pulse sequence, validated the numerical simulations through phantom experiments, and performed MRS scans on eight healthy volunteers for in vivo quantification of glutamate, glutamine and other metabolites such as GSH. Methods: Pulse sequence optimization: The pulse sequence consists of PRESS localization with a J-suppression RF pulse inserted at the midpoint between the two refocusing pulses. The J-suppression pulse is a frequency selective s...
Target audience: Scientists and clinicians who are interested in measuring glutamate (Glu) and gl... more Target audience: Scientists and clinicians who are interested in measuring glutamate (Glu) and glutamine (Gln) using magnetic resonance spectroscopy (MRS). Purpose: In vivo measurements of Glu and Gln in the human brain are important for studying many neurological and psychiatric diseases because Glu is a vital link between brain energy metabolism and glutamatergic neurotransmission. Spectral separation of glutamate, glutamine, and other coupled spins at 3T is difficult. Recently, Choi et al. [1] proposed to use a TE optimized PRESS (point-resolved spectroscopy) method at 7T to resolve glutamate and glutamine, taking advantage of the chemical shift offset artifact [2,3] to suppress overlapping signals from the aspartyl moiety of NAA. In this work, we propose to suppress spectral interference from the aspartyl moiety of NAA by a selective RF pulse placed at the resonance frequency of the NAA aspartyl CH proton at 4.38 ppm, which alters the J-evolution of the NAA aspartyl CH2 multiple...
Edited MRS sequences are widely used for studying GABA in the human brain. Several algorithms are... more Edited MRS sequences are widely used for studying GABA in the human brain. Several algorithms are available for modelling these data, deriving metabolite concentration estimates through peak fitting or a linear combination of basis spectra. The present study compares seven such algorithms, using data obtained in a large multi-site study.GABA-edited (GABA+, TE = 68 ms MEGA-PRESS) data from 222 subjects at 20 sites were processed via a standardised pipeline, before modelling with FSL-MRS, Gannet, AMARES, QUEST, LCModel, Osprey and Tarquin, using standardised vendor-specific basis sets (for GE, Philips and Siemens) where appropriate.After referencing metabolite estimates (to water or creatine), systematic differences in scale were observed between datasets acquired on different vendors’ hardware, presenting across algorithms. Scale differences across algorithms were also observed.Using the correlation between metabolite estimates and voxel tissue fraction as a benchmark, most algorithm...
Lawrence Berkeley Lab Nucl Waste Isolation Geophys and Reservoir Eng Geosci, Aug 30, 1982
Introduction GABA detection faces the problem of contamination from co-edited macromolecule signa... more Introduction GABA detection faces the problem of contamination from co-edited macromolecule signal at 3.0 ppm (MM30) when using the MEGA-PRESS technique [1]. Therefore, direct quantification of GABA by LCModel software [2] yields the sum of GABA and MM30. One of the proposed methods to eliminate MM30 is to alternate the editing pulse between 1.9 ppm and 1.5 ppm, the latter a position symmetric to 1.9 ppm with respect to the J-coupled MM resonance at 1.7 ppm [3]. New MM basis have also been introduced into LCModel analysis [4], and a soft constraint has been applied to better quantify GABA [5]. In this study, we compare three LCModel fitting approaches for both the original MEGA-PRESS and the modified “MM-symmetric” sequence which has the editing pulse alternating between 1.9 ppm and 1.5 ppm.
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2007
Ziele: Spektroskopische Bildgebung (SI: Spectroscopic Imaging oder CSI: Chemical Shift Imaging) w... more Ziele: Spektroskopische Bildgebung (SI: Spectroscopic Imaging oder CSI: Chemical Shift Imaging) wird in der Magnet-Resonanz-Spektroskopie genutzt, um lokale Konzentrationsanderungen von Metaboliten in-vivo aufzuspuren. Die raumliche Position wird phasenkodiert, und ein Spektrum wird nach jedem Phasenkodierschritt aufgenommen, um somit im Gesamtvolumen die Spektren von vielen Teilvolumina (Voxel) aufzunehmen. Diese Studie untersucht SI des menschlichen Gehirns bei ultra-hohen Magnetfeldstarken und zeigt Losungswege, Magnetfeldinhomogenitaten und Suszeptibilitatsartefakte zu verringern. Methode: Spektrokopische Bildgebung des menschlichen Gehirns wurde an 7 Probanden in einem 7T Gankorper-MR-Tomographen (Philips Medical Systems) mit einer Sende/Empfangs-Kopfspule durchgefuhrt. Transversale Spin-Echo-Schichtlokalisation wurde mit den folgenden Parametern TR=1500ms, TE=144ms, Field of View=250mm, 28×28 Matrix, Schichtdicke=20mm und NEX=1 durchgefuhrt. SI wurde in einem Probanden zusatzlich mit einer kurzen Echozeit TE=26ms untersucht. Ergebnis: Hochaufgeloste MR-Spektren konnten im Gehirn aller Probanden aufgenommen werden. Die Resonanzen von Cholin, Creatin, N-Acetylaspartat und Myoinositol wurden in allen SI-Voxeln des Gehirns identifiziert. SI mit kurzer Echozeit loste zusatzlich die Resonanzen von Glutamate, Glutamine und Scylloinositol auf. Schlussfolgerung: SI ist bei ultrahohen Magnetfeldstarken moglich und erhoht die Sensitivitat und die spektrale Auflosung in der Magnet-Resonanz-Spektroskopie. Eine PRESS-Lokalisation ist aufgrund der Chemical-Shift-Verschiebung bei ultra-hohen Feldern nicht praktikabel, stattdessen ist eine Spin-Echo Schichtlokalisation zu bevorzugen. Ein Shim zweiter Ordnung minimiert die Linieverbreiterung der Spektrallinien, die durch starke Suszeptiblitatseffekte bei hohen Magnetfeldstarken hervorgerufen werden. Ultrahochfeld SI verbessert die nicht-invasive Charakterisierung und Quantifizierung von molekularen Markern bei einer Vielzahl neurologischer Erkrankungen. Korrespondierender Autor: Sammet S The Ohio State University, Department of Radiology, 1654 Upham Drive, 43210 Columbus E-Mail: sammet.5@osu.edu
Sports Medicine, 2021
Muscle fibre typology as a novel risk factor for hamstring strain injuries in professional footba... more Muscle fibre typology as a novel risk factor for hamstring strain injuries in professional football (soccer): a prospective cohort study RUNNING HEAD:
American Journal of Neuroradiology, 2010
is an established noninvasive MR imaging technique that can be helpful in the diagnosis of brain ... more is an established noninvasive MR imaging technique that can be helpful in the diagnosis of brain lesions and in treatment planning. Claustrophobia and body habitus preclude some patients from routine MR imaging in a closed-bore system. The development of 1 H-MR spectroscopy for use in an open MR imaging system would enable a more complete characterization of brain lesions in these patients. ABBREVIATIONS: CH 2 ϭ methyl; Cho ϭ choline; Cr ϭ creatine; FLAIR ϭ fluid-attenuated inversion recovery; 1 H-MR spectroscopy ϭ proton MR spectroscopy; NAA ϭ N-acetylaspartate; PML ϭ progressive multifocal leukoencephalopathy; PRESS ϭ point-resolved spectroscopic sequence; SNR ϭ signal-to-noise ratio; SVS ϭ single-voxel spectroscopy