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Depth and refocusing pulses designed for multipulse NMR with surface coils
073&725X/84 $03.00+.00 Copyright 0 1984 Pergamon Press Ltd.
Mogneric Resonance Imaging. Vol. 2. pp. 147-158, 1984 Printed in the USA. All rights reserved.
l Abstracts In an effort to keep our readership informed of important developments in magnetic resonance imaging as reported in the literature, this Abstracts section will be an ongoing feature of Magnetic Resonance Imaging and will be edited by Lawrence A. Minkoff, Ph.D.
TECHNICAL
by 0.1 to 0.3 units in solution with a given ionic strength depending on the species of ion. The form of the titration curve varied with temperature. Based on these results, the value of 6.75 was obtained with the uncertainty of 0.12 for the intracellular pK’ of frog muscle at 24OC. J. Biochem. 94:729; 1983
PAPERS
Differentiating Senile Dementia of Alzheimer Type and Multi-Infarct Dementia by Proton NMR Imaging J. A. 0. Besson,’ F. M. Corrigan,’ G. W. Ashcroft,’ L. M. Eastwood,’
E. Iljon Foreman,’ F. W. Smith3
‘Department of Mental Health, University of Aberdeen, Royal Cornhill Hospital, Aberdeen AB9 2ZH; ‘Department of Biomedical Physics, University of Aberdeen; ‘Department of Nuclear Medicine. Aberdeen Royal Infirmary
Depth and Refocusing Pulses Designed for Multipulse NMR with Surface Coils M. Robin Bendall’ and Roy E. Gordon’
Proton NMR measures on white-matter permit the differentiation of senile dementia of Alzheimer type from multi-infarct dementia and from non-dementia in situations where visual lesions are not detected and where other imaging techniques are inconclusive. Lancet, October 1:789; 1983
‘School of Science, Grifith University, Nathan 4111, Queensland, Australia; ‘Oxford Research Systems Limited, Osney Mead, Oxford, OX2 00X, England When surface radiofrequency coils are used for irradiation and detection, the pulse angles are greatest in the plane of the coil and decrease rapidly with depth of penetration into the sample and this intrinsic spatial variation in pulse angle makes it difficult to use multipulse NMR techniques. However, it is shown that spin-echo pulse sequences may still be used provided the 7r refocusing pulses are cycled through all four phases as described by Bodenhausen et al. (J. Magn. Resort. 27, 511 (1977)). This has the added advantage that signals are markedly reduced from sample regions where there is a large deviation from an idealxpulseangle.Thusthe?r/2-?-a[+~, *y]-TV scheme also functions as a “depth” pulse sequence, and this property is preserved even when there are no T delay periods. Additional depth discrimination is obtained by using additional phase-cycled K pulses, e.g., the “depth pulse”: x/f;r[*x, +y];r[*x, ky]. Analysis of the x/2 phase alternation introduced by Demco et al. (J. Magn. Reson. 16, 467 (1974)) for inversion-recovery T, measurements shows that when this is combined with the above cycled 7r pulses, additional depth discrimination is obtained and accurate T, measurements may be made even when there are large divergences from the ideal pulse angles. Thus 7r;7r/2[ *~];a[ fx, +y];x[ kx, +y] is a very good depth
Intracellular pH Determination by a “P-NMR Technique. The Second Dissociation Constant of Phosphoric Acid in a Biological System Yoshiteru Sea,’ Masataka Murakami,’ Hiroshi Watari, Yusuke Imai,* Kazuo Yoshizaki,’ Hiroyasu Nishikawa,’ Taketoshi Morimoto’ ‘Department of Physiology, Kyoto Prefectural University of Medirine. Kamigyo-ku, Kyoto, Kyoto 602; ‘Department of Physiology, Osaka Medical College, Takatsuki, Osaka 569; 3Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Aichi 444 To evaluate the accuracy of pH determination by 3’P-NMR, factors which influence the pK value of phosphate were appraised on the basis of the titration of 1 mM phosphate buffer solution. When the method is used for the determination of cytoplasmic pH, ionic strength is the major factor causing shifts of apparent pK (pK’) value, and the magnitude of the shift can be predicted from the ionic strength calculated by means of the Debye-Htickel equation. Ions (Na+, K+, Mg2+, and Ca*+) and salivary protein affected the pK’ value 147
148
Magnetic Resonance Imaging.
pulse, ~-7-7r/2[ *xl; 7r[ *x, +y];r[ +x, +y] may be used for inversion-recovery T, measurements and a;*/ 2[ +x1; r[ fx, ky] --7_7r[ +x, ky] -Tmay be used for spin-echo sequences. Several simple spin-echo sequences are presented. These techniques help to relax the constraints on radiofrequency coil design imposed by the requirement to have good B, homogeneity and therefore may have more general application, especially in cases where the need for a large filling factor is at a premium. J. Magn. Res. 53:365; 1983 Experimental Verification with Surface Coils
of Depth Pulses
M. Robin Bendall’ and Walter
Applied
P. Aue’
‘School of Science, Griflth University, Nathan 4111) Queensland, Australia; ‘Biozentrum, der Universitiit Basel. Abt. Biophysikalische Chemie. CH-4056 Basel, Switzerland
Volume 2, Number 2, 1984
and in T, relaxation times equalled the sensitivity of histologic findings for the detection of early stages of hepatitis. A significant shift in T, relaxation times characterized the early stages of hepatic necrosis. Liver triglyceride content correlated significantly with increases in NMR intensity measurements (p < 0.01); however, changes in liver water content had a much greater influence on intensity, T,, and T,. Thus, it may be possible to distinguish hepatitis from benign fatty liver. Liver iron content correlated with decreases in N MR intensity measurements (p < O.OOl), and iron levels as low as 1.2 mg/g were detected. NMR may more specifically identify hepatocellular iron overload than do other techniques that do not distinguish hepatocellular from reticuloendothelial iron. Radiology 148:743; 1983 Experimental Protocol Vitro by NMR R. Mathur-De
Portable NMR Sample Localization Inhomogeneous rf Irradiation Coils
Method
Using
M. Robin Bendall School of Science, Griffith Queensland 4111, Australia
University,
Nathan.
In NMR spectroscopy, a phase-cycled multipulse scheme has been shown to discriminate against sample regions where pulse angles differ markedly from ideal a/2 and K angles. Potentially, the method may be used with multiple inhomogeneous rf coils to obtain a spectrum from a localized region of a large sample, and this is illustrated by a first attempt with a double surface coil. Chem. P. Lett. August 12:310; 1983 Nuclear Magnetic Resonance tally Induced Liver Disease
Imaging of Experimen-
David D. Stark,’ MD, Nathan M. Bass,3 MD, PhD, Albert A. Moss,’ MD, Bruce R. Bacon,’ MD, James H. McKerrow,’ MD, Christopher E. Cann.’ PhD, Anthony Brito,’ BSc, Henry I. Goldberg,’ MD Departments of Radiology’ and Pathology,’ the Gastrointestinal Research Unit and Liver Center,’ and the Radiologic Imaging Laboratory,J University of California, San Francisco, CA; and the Department of Medicine, Case Western Reserve University, Cleveland, OH’ Experimental animal models of hepatitis, fatty liver, and hepatic iron overload were evaluated using a 3.5-kGauss nuclear magnetic resonance (NMR) imaging system. Increases in image intensity measurements
for Tissue
Vr&,’ R. Grimte,’
Discrimination
in
and M. P. Rosa’
‘lnstitut d’Hygi&e et d*Epidkmiologie, 14 Rue Juliette Wytsman, 1050 Brussels, Belgium; ‘Institut MCdico Chirurgical, Rue Paquot, 1050 Brussels, Belgium We have examined the NMR relaxation times T, and TZof water protons for liver (mouse, human) and brain (mouse) at different temperatures and subjected to various conditions of conservation and degeneration. After tissue degeneration, T, and T, behave differently and their variations are characteristic of each tissue type. The results show that the initial values at +4OC are consistent when the experimental protocol formulated in this study is followed. Biosci. Rep. 3:599; 1983 Nuclear Magnetic Resonance: A Gray Scale Model for Head Images Ronald T. Droege,’ PhD, Stephen N. Wiener,’ MD, Mark S. Rzeszotarski,’ PhD, G. Neil Holland,* MPhil, Ian R. Young,j PhD ‘Mt. Sinai Medical Center, Cleveland, Ohio; ‘Picker International, Highland Heights, Ohio; ’ Wembley, London, England The gray scale of nuclear magnetic resonance (N MR) head images is explained in terms of tissue and machine parameters. Tissue parameters considered here include the spin-lattice relaxation time, the spinspin relaxation time. and the proton density. Machine parameters include the pulse sequence (saturation recovery, inversion recovery, or spin echo), the repetition time, and the delay time. The ability of the operator to alter the NMR gray scale predictably is
Mogneric Resonance Imaging. Vol. 2. pp. 147-158, 1984 Printed in the USA. All rights reserved.
l Abstracts In an effort to keep our readership informed of important developments in magnetic resonance imaging as reported in the literature, this Abstracts section will be an ongoing feature of Magnetic Resonance Imaging and will be edited by Lawrence A. Minkoff, Ph.D.
TECHNICAL
by 0.1 to 0.3 units in solution with a given ionic strength depending on the species of ion. The form of the titration curve varied with temperature. Based on these results, the value of 6.75 was obtained with the uncertainty of 0.12 for the intracellular pK’ of frog muscle at 24OC. J. Biochem. 94:729; 1983
PAPERS
Differentiating Senile Dementia of Alzheimer Type and Multi-Infarct Dementia by Proton NMR Imaging J. A. 0. Besson,’ F. M. Corrigan,’ G. W. Ashcroft,’ L. M. Eastwood,’
E. Iljon Foreman,’ F. W. Smith3
‘Department of Mental Health, University of Aberdeen, Royal Cornhill Hospital, Aberdeen AB9 2ZH; ‘Department of Biomedical Physics, University of Aberdeen; ‘Department of Nuclear Medicine. Aberdeen Royal Infirmary
Depth and Refocusing Pulses Designed for Multipulse NMR with Surface Coils M. Robin Bendall’ and Roy E. Gordon’
Proton NMR measures on white-matter permit the differentiation of senile dementia of Alzheimer type from multi-infarct dementia and from non-dementia in situations where visual lesions are not detected and where other imaging techniques are inconclusive. Lancet, October 1:789; 1983
‘School of Science, Grifith University, Nathan 4111, Queensland, Australia; ‘Oxford Research Systems Limited, Osney Mead, Oxford, OX2 00X, England When surface radiofrequency coils are used for irradiation and detection, the pulse angles are greatest in the plane of the coil and decrease rapidly with depth of penetration into the sample and this intrinsic spatial variation in pulse angle makes it difficult to use multipulse NMR techniques. However, it is shown that spin-echo pulse sequences may still be used provided the 7r refocusing pulses are cycled through all four phases as described by Bodenhausen et al. (J. Magn. Resort. 27, 511 (1977)). This has the added advantage that signals are markedly reduced from sample regions where there is a large deviation from an idealxpulseangle.Thusthe?r/2-?-a[+~, *y]-TV scheme also functions as a “depth” pulse sequence, and this property is preserved even when there are no T delay periods. Additional depth discrimination is obtained by using additional phase-cycled K pulses, e.g., the “depth pulse”: x/f;r[*x, +y];r[*x, ky]. Analysis of the x/2 phase alternation introduced by Demco et al. (J. Magn. Reson. 16, 467 (1974)) for inversion-recovery T, measurements shows that when this is combined with the above cycled 7r pulses, additional depth discrimination is obtained and accurate T, measurements may be made even when there are large divergences from the ideal pulse angles. Thus 7r;7r/2[ *~];a[ fx, +y];x[ kx, +y] is a very good depth
Intracellular pH Determination by a “P-NMR Technique. The Second Dissociation Constant of Phosphoric Acid in a Biological System Yoshiteru Sea,’ Masataka Murakami,’ Hiroshi Watari, Yusuke Imai,* Kazuo Yoshizaki,’ Hiroyasu Nishikawa,’ Taketoshi Morimoto’ ‘Department of Physiology, Kyoto Prefectural University of Medirine. Kamigyo-ku, Kyoto, Kyoto 602; ‘Department of Physiology, Osaka Medical College, Takatsuki, Osaka 569; 3Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Aichi 444 To evaluate the accuracy of pH determination by 3’P-NMR, factors which influence the pK value of phosphate were appraised on the basis of the titration of 1 mM phosphate buffer solution. When the method is used for the determination of cytoplasmic pH, ionic strength is the major factor causing shifts of apparent pK (pK’) value, and the magnitude of the shift can be predicted from the ionic strength calculated by means of the Debye-Htickel equation. Ions (Na+, K+, Mg2+, and Ca*+) and salivary protein affected the pK’ value 147
148
Magnetic Resonance Imaging.
pulse, ~-7-7r/2[ *xl; 7r[ *x, +y];r[ +x, +y] may be used for inversion-recovery T, measurements and a;*/ 2[ +x1; r[ fx, ky] --7_7r[ +x, ky] -Tmay be used for spin-echo sequences. Several simple spin-echo sequences are presented. These techniques help to relax the constraints on radiofrequency coil design imposed by the requirement to have good B, homogeneity and therefore may have more general application, especially in cases where the need for a large filling factor is at a premium. J. Magn. Res. 53:365; 1983 Experimental Verification with Surface Coils
of Depth Pulses
M. Robin Bendall’ and Walter
Applied
P. Aue’
‘School of Science, Griflth University, Nathan 4111) Queensland, Australia; ‘Biozentrum, der Universitiit Basel. Abt. Biophysikalische Chemie. CH-4056 Basel, Switzerland
Volume 2, Number 2, 1984
and in T, relaxation times equalled the sensitivity of histologic findings for the detection of early stages of hepatitis. A significant shift in T, relaxation times characterized the early stages of hepatic necrosis. Liver triglyceride content correlated significantly with increases in NMR intensity measurements (p < 0.01); however, changes in liver water content had a much greater influence on intensity, T,, and T,. Thus, it may be possible to distinguish hepatitis from benign fatty liver. Liver iron content correlated with decreases in N MR intensity measurements (p < O.OOl), and iron levels as low as 1.2 mg/g were detected. NMR may more specifically identify hepatocellular iron overload than do other techniques that do not distinguish hepatocellular from reticuloendothelial iron. Radiology 148:743; 1983 Experimental Protocol Vitro by NMR R. Mathur-De
Portable NMR Sample Localization Inhomogeneous rf Irradiation Coils
Method
Using
M. Robin Bendall School of Science, Griffith Queensland 4111, Australia
University,
Nathan.
In NMR spectroscopy, a phase-cycled multipulse scheme has been shown to discriminate against sample regions where pulse angles differ markedly from ideal a/2 and K angles. Potentially, the method may be used with multiple inhomogeneous rf coils to obtain a spectrum from a localized region of a large sample, and this is illustrated by a first attempt with a double surface coil. Chem. P. Lett. August 12:310; 1983 Nuclear Magnetic Resonance tally Induced Liver Disease
Imaging of Experimen-
David D. Stark,’ MD, Nathan M. Bass,3 MD, PhD, Albert A. Moss,’ MD, Bruce R. Bacon,’ MD, James H. McKerrow,’ MD, Christopher E. Cann.’ PhD, Anthony Brito,’ BSc, Henry I. Goldberg,’ MD Departments of Radiology’ and Pathology,’ the Gastrointestinal Research Unit and Liver Center,’ and the Radiologic Imaging Laboratory,J University of California, San Francisco, CA; and the Department of Medicine, Case Western Reserve University, Cleveland, OH’ Experimental animal models of hepatitis, fatty liver, and hepatic iron overload were evaluated using a 3.5-kGauss nuclear magnetic resonance (NMR) imaging system. Increases in image intensity measurements
for Tissue
Vr&,’ R. Grimte,’
Discrimination
in
and M. P. Rosa’
‘lnstitut d’Hygi&e et d*Epidkmiologie, 14 Rue Juliette Wytsman, 1050 Brussels, Belgium; ‘Institut MCdico Chirurgical, Rue Paquot, 1050 Brussels, Belgium We have examined the NMR relaxation times T, and TZof water protons for liver (mouse, human) and brain (mouse) at different temperatures and subjected to various conditions of conservation and degeneration. After tissue degeneration, T, and T, behave differently and their variations are characteristic of each tissue type. The results show that the initial values at +4OC are consistent when the experimental protocol formulated in this study is followed. Biosci. Rep. 3:599; 1983 Nuclear Magnetic Resonance: A Gray Scale Model for Head Images Ronald T. Droege,’ PhD, Stephen N. Wiener,’ MD, Mark S. Rzeszotarski,’ PhD, G. Neil Holland,* MPhil, Ian R. Young,j PhD ‘Mt. Sinai Medical Center, Cleveland, Ohio; ‘Picker International, Highland Heights, Ohio; ’ Wembley, London, England The gray scale of nuclear magnetic resonance (N MR) head images is explained in terms of tissue and machine parameters. Tissue parameters considered here include the spin-lattice relaxation time, the spinspin relaxation time. and the proton density. Machine parameters include the pulse sequence (saturation recovery, inversion recovery, or spin echo), the repetition time, and the delay time. The ability of the operator to alter the NMR gray scale predictably is