76
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Nosel W, Trimble LA, Shen JF, Allen PS. On the use of double-quantum coherence from an AX3 system (protons in lactate) for spectral editing. Magn Reson Med 1989; 11:398-404. [PMID: 2550720 DOI: 10.1002/mrm.1910110314] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The suppression of water signals in in vivo proton spectra by means of multiple-quantum filtering can be brought about in several ways. This communication exposes the shortcomings of using purely subtractive filtering techniques to observe signals from metabolites that contain proton couplings of the form AX3.
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77
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Matheson GO, Ellinger DC, Gheorghiu D, Hochachka PW, McKenzie DC, Quinney AH, Allen PS. IN VIVO 31P NMR OF ELECTRICALLY STIMULATED HUMAN QUADRICEPS MUSCLE. Med Sci Sports Exerc 1989. [DOI: 10.1249/00005768-198904001-00099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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78
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Phillips DM, Allen PS, Man SF. Assessment of temporal changes in pulmonary edema with NMR imaging. J Appl Physiol (1985) 1989; 66:1197-208. [PMID: 2496087 DOI: 10.1152/jappl.1989.66.3.1197] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nuclear magnetic resonance imaging (NMRI) parameters [longitudinal relaxation time (T1), transverse relaxation time (T2), and signal intensity] acquired at a magnetic field of 2.35 T were validated with a study of nine different phantom gel solutions. This technique was then applied to study 13 anesthetized supine cats, among which 10 had lung edema induced by oleic acid (0.075 ml/kg); the result was compared with postmortem analyses of lung water. Three animals (series A) were imaged until the edema was first visualized in NMRI, usually 15-20 min after oleic acid infusion. Another seven animals (series B) were imaged over 4-5 h. As lung water increased, so did the signal intensity. When edema first appeared, T1, T2, and the volume of the edematous region within the slice in the upper lobes showed no gravity-dependent differences; this was confirmed by postmortem measurements (series A) of lung water. With time, gravity-dependent regions displayed greater volumes of edematous regions and greater T1 values (P less than 0.01), suggesting a continued accumulation of lung water. In comparison, nondependent regions displayed constant volumes of edematous region and lesser T1 values (P less than 0.01), suggesting an increased protein concentration but no change in lung water. This study suggests the potential applicability of NMRI parameters in the assessment of pulmonary edema.
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79
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Damji AA, Snyder RE, Ellinger DC, Witkowski FX, Allen PS. RF interference suppression in a cardiac synchronization system operating in a high magnetic field NMR imaging system. Magn Reson Imaging 1988; 6:637-40. [PMID: 3210907 DOI: 10.1016/0730-725x(88)90086-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
An electrocardiographic (ECG) unit suitable for cardiac-synchronized nuclear magnetic resonance imaging in high magnetic fields is presented. The unit includes lossy transmission lines as ECG leads in order to suppress radio frequency (RF) interference in the electrocardiogram. The unit's immunity to RF interference is demonstrated.
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80
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Hanstock CC, Lunt JA, Allen PS. The modification of the RF field distribution of surface coils by weakly conducting saline samples. Magn Reson Med 1988; 7:204-9. [PMID: 3398767 DOI: 10.1002/mrm.1910070208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The modification of the RF field distribution of a surface coil, which is brought about by both loading and skin effect conditions arising from the proximity of weakly conducting saline samples, is demonstrated. A procedure for the calibration of the depth of the spectral acquisition region in depth-pulse localized in vivo spectroscopy is shown to be acceptable.
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81
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Stewart CA, Hanstock CC, Allen PS. The application of depth-pulse localized 31P NMR spectroscopy to monitor tumor metabolism and response to chemotherapy in the rat kidney. Magn Reson Med 1988; 7:100-10. [PMID: 3386515 DOI: 10.1002/mrm.1910070112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
To illustrate the spatial variations in metabolism within tumors, 31P spectral data are presented from a predefined, depth-pulse localized region of a rat kidney impregnated with Walker sarcoma cells. These data display the changes in energy metabolism during infiltration of the kidney by the tumor and during treatment of the tumor with cyclophosphamide.
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82
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Hanstock CC, Boisvert DP, Bendall MR, Allen PS. In vivo assessment of focal brain lactate alterations with NMR proton spectroscopy. J Cereb Blood Flow Metab 1988; 8:208-14. [PMID: 2830290 DOI: 10.1038/jcbfm.1988.51] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Spectral editing techniques and localization of 1H signals were applied to monitor lactate accumulation in a circumscribed region of brain damage. The experiments were performed at 2.35 T (100 MHz) in a 40-cm bore magnet. Following unilateral craniectomy in anesthetized adult cats, a two-turn surface coil was positioned over the dural surface. Proton spectra were obtained before and 1-5 h after production of a cortical cold lesion from three curved shells of brain tissue, each approximately 3 mm thick. The localized spectrum was obtained from each region with and without spectral difference editing for the lactate CH3 protons, but always with the maximum excitation produced by the semiselective binomial pulse centered on the lactate CH3 resonance. Region 1 represented the damaged area, Region 2 was located immediately below Region 1, and Region 3 was immediately below Region 2. Spin-echo magnetic resonance imaging was used to confirm the relationship between the location of the lesion and the regions from which the spectra were obtained. Spectra obtained without lactate editing showed, in addition to the N-acetylaspartate peak, a large lactate peak in Region 1 after production of the cold lesion. In Regions 2 and 3, changes in lactate were more difficult to assess owing to the presence of a lipid peak at a similar frequency that results from incomplete suppression by the spin-echo pulse sequence alone. Spectra acquired using lactate editing did not contain the lipid peak and clearly showed relatively small lactate accumulations in Regions 2 and 3.(ABSTRACT TRUNCATED AT 250 WORDS)
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83
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Phillips DM, Lunt JA, Man SF, Allen PS. Multiple spin echo imaging and quantitative relaxation measurements of pulmonary edema. Magn Reson Imaging 1987; 5:137-47. [PMID: 3586880 DOI: 10.1016/0730-725x(87)90043-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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84
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Lunt JA, Allen PS, Brauer M, Swinamer D, Treiber EO, Belcastro A, Eccles R, King EG. An evaluation of the effect of fasting on the exercise-induced changes in pH and Pi/PCr from skeletal muscle. Magn Reson Med 1986; 3:946-52. [PMID: 3821470 DOI: 10.1002/mrm.1910030616] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The changes in the response of skeletal muscle to maximal dynamic exercise were investigated in going from a fasted state to a refed state by means of 31P NMR spectroscopy. It was found that in the fasted state, exercise-induced changes in Pi/PCr and in pH were both inhibited, in comparison with those in the refed state.
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85
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Raleigh JA, Franko AJ, Treiber EO, Lunt JA, Allen PS. Covalent binding of a fluorinated 2-nitroimidazole to EMT-6 tumors in Balb/C mice: detection by F-19 nuclear magnetic resonance at 2.35 T. Int J Radiat Oncol Biol Phys 1986; 12:1243-5. [PMID: 3744946 DOI: 10.1016/0360-3016(86)90268-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A hexafluorinated 2-nitroimidazole (CCI-103F) has been synthesized and its properties as a hypoxic cell binder investigated. The drug has a plasma half-life of 90 min in Balb/C mice and a tumor-to-plasma ratio of 0.8. Following sustained exposure to the drug and a washout period for the unbound drug, liver and tumor samples were excised. NMR investigation of the excised tissue in a 2.35 T animal sized NMR facility revealed the presence of 19F bound to both tissues. Further improvement in sensitivity is required to make 19F NMR detection of binding in situ feasible.
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86
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Allen PS, Castro ME, Treiber EO, Lunt JA, Boisvert DP. A proton NMR relaxation evaluation of a model of brain oedema fluid. Phys Med Biol 1986; 31:699-711. [PMID: 3749258 DOI: 10.1088/0031-9155/31/7/001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Using CSF/protein solutions as models of vasogenic extracellular fluid, the concentration dependences of longitudinal and transverse proton relaxation rates have been measured at 37 degrees C and 100 MHz for the serum proteins, albumin, IgG, a 2.8:1 mixture of albumin and IgG and human serum itself. These measurements have been used to determine the sensitivity of proton relaxation rates to the amount and the type of the protein in oedema fluid, and to establish the significance of both of these factors in relation to a separation of vasogenic from cytotoxic oedema. An extension of the two-environment rapid-exchange model of solvent relaxation is presented, which accounts for the measurements on protein mixtures and which enables estimates to be made of the number and the transverse relaxation rate of water protons associated with the protein surface.
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87
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Reid RS, Koch CJ, Castro ME, Lunt JA, Treiber EO, Boisvert DJ, Allen PS. The influence of oxygenation on the 19F spin-lattice relaxation rates of fluosol-DA. Phys Med Biol 1985; 30:677-86. [PMID: 4023055 DOI: 10.1088/0031-9155/30/7/006] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The spin-lattice relaxation rates (1/T1) were measured at 94.1 MHz for six peaks in the 19F NMR spectrum of the perfluorochemical blood substitute fluosol-DA, which contains a mixed emulsion of perfluorodecalin and perfluorotripropylamine. Each of these rates increased linearly with the percentage of oxygen dissolved in the emulsion. Relative values of the linear increase for different peaks established that, for perfluorotripropylamine in the mixed emulsion, the oxygen-fluorocarbon interaction is loosely but preferentially oriented in a manner similar to that previously established for other pure fluorocarbons. The uncertainty in the oxygen level estimated from T1 measurements is somewhat less than 5% O2 and it is thus established that quantitative non-invasive oxygenation measurements can be made to sufficient precision by this approach, using fluosol-DA and 19F spin-lattice relaxation.
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88
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Levin LS, Allen PS, Fetterhoff CK. Lateral periodontal cyst: a case report. JOURNAL OF THE MARYLAND STATE DENTAL ASSOCIATION 1983; 26:18-20. [PMID: 6586946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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89
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Abstract
Nuclear magnetic resonance (NMR) techniques are now finding exciting new noninvasive applications in medicine. There are two major approaches. The first is as an analytical technique using 31P NMR spectroscopy for the identification and quantitation of the more abundant phosphate metabolites in various tissues. Changes in the levels of these metabolites and in intracellular cytoplasmic pH can be followed in various ischemic and hypoxic conditions to monitor metabolic response to stress situations and to diagnose inborn errors of metabolism. The second major approach is an entirely different application of NMR techniques and uses 1H, the nucleus most abundant in biological tissues, largely in water and fats, to produce NMR images of any section of the body. By applying non-uniform magnetic fields across a section of the body, hydrogen nuclei in different elemental volumes in the section are tagged with different frequencies and their signals can be processed to give an image of the section. In contrast to computed tomographic scanning, NMR has particularly powerful application in the imaging of soft tissues.
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90
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Abstract
A case of a 27-year-old black woman with typical findings of a large, asymptomatic myxoma involving the entire left half of the mandible is presented. The lesion was treated by a partial mandibulectomy and secondary bone graft with a titanium tray and condyle prosthesis. A comparison of the patient's bitewing, periapical, and panoramic radiographs was made. The lesion was not visible on the bitewings and was overlooked on the periapical films, but was clearly visible on the panoramic radiograph. The screening value of this radiograph was stressed.
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91
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Lumley J, Allen PS, Plovanic P, Wood C, Walters W. The prepregnancy clinic. BRITISH MEDICAL JOURNAL 1980; 281:619. [PMID: 7427398 PMCID: PMC1713912 DOI: 10.1136/bmj.281.6240.619-c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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92
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Matheson GO, Ellinger DC, Gheorghiu D, Hochachka PW, McKenzie DC, Quinney AH, Allen PS. IN VIVO 31P NMR OF ELECTRICALLY STIMULATED HUMAN QUADRICEPS MUSCLE. Med Sci Sports Exerc 1980. [DOI: 10.1249/00005768-198004001-00099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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93
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Allen PS. Another look at preventive dentistry. APEX 1973; 7:135-7. [PMID: 4525745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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94
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Allen PS, Khanzada AWK, McDowell CA. Nuclear magnetic resonance absorption and relaxation study oftert‐butylamine andtert‐butylamine clathrate deuterate. J Chem Phys 1973. [DOI: 10.1063/1.1679831] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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95
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Lipp MR, Benson SG, Allen PS. Marijuana use by nurses and nursing students. Am J Nurs 1971; 71:2339-41. [PMID: 5209456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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96
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Allen PS, Cowking A. Nuclear Magnetic Resonance Study of Hindered Rotations in Some Methylbenzenes. J Chem Phys 1968. [DOI: 10.1063/1.1670141] [Citation(s) in RCA: 53] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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97
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98
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Allen PS, Cowking A. Nuclear Magnetic Resonance Study of Molecular Motions in Hexamethylbenzene. J Chem Phys 1967. [DOI: 10.1063/1.1701629] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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