bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparison of the chemical analyses of cell lipids with their complete proton NMR spectrum
Authors: Holmes K. T. , Williams P. G. , King N. J. C. , May G. L. , Dyne M. , Bloom M. , Mountford E. 
Published: March 2007

AbstractWhole cells are made up of molecules in different environments to which NMR spectroscopy is sensitive. In particular, malignant and transformed cells contain lipids not only in bilayers but in isotropically tumbling domains which give rise to high‐resolution spectra. We have recently developed a technique for simultaneously analyzing broadline and high‐resolution signals (M. Bloom, K. T. Holmes, C. E. Mountford, and P. G. Williams, J. Magn. Reson., in press) and we report here its application to a range of rat, mouse, and human cell lines. Some selected features of the NMR spectra were compared with the chemical analysis of the whole‐cell lipid. We found that in general the proportion of protons in the narrow methylene resonance at 1.3 ppm increased with the neutral lipid content of the cells. This peak was chosen because its T2 relaxation behavior correlates with metastatic potential in a rat model system. This new technique could be applied to other high‐resolution components both in healthy and in diseased states. © 1987 Academic Press, Inc.
Proton NMR spectroscopy in myocardial ischemic insult
Authors: Evanochko William T. , Reeves Russell C. , Sakai Ted T. , Canby Robert C. , Pohost Gerald M. 
Published: March 2007

AbstractProton NMR methods can monitor mobile lipids (e.g., fatty acids and glycerides) in intact tissue. Lipids play a major role in cardiac energy production, and elevated levels of myocardial lipids have been reported following an ischemic insult. The present study examines the potential of high‐resolution 1H NMR spectroscopy to monitor lipid alterations 24 h following coronary occlusion in dogs, and to correlate these finds with regional myocardial blood flow (RMBF) measured by radiolabeled microspheres. The dogs were killed, and samples of excised myocardium were studied by high‐resolution 1H NMR spectroscopic analysis using solvent suppression in combination with the Hahn spin‐echo pulse sequence. Mobile lipids levels in myocardium with moderate blood flow reduction (28.6 f 7, integral values, arbitrary units; flow 5–50% of control) were significantly elevated compared to the mobile lipid levels in control myocardium (5.3 ± 8, P < 0.001) and in myocardium with severe flow reduction (7.2 ± 10, P < 0.001; flow 5% of control). The mobile lipids in myocardium with severe flow reduction were not elevated significantly relative to control tissue. As anticipated, depression in the level of creatine paralleled the microsphere determined degree of ischemia, i.e., compared to control (9.0 ± 3); creatine levels were moderately decreased with flows 5–50% of control (5.5 ± 4, P < 0.001) and markedly decreased with flows < 5% of control (1.0 ± 2, P < 0.001). This study suggests that high‐resolution 1H NMR spectroscopy may be used to evaluate alterations in myocardial lipid levels following an ischemic insult. This observation, in addition to changes in other selected metabolites, may provide diagnostic and pathophysiologic insight into the severity of the myocardial injury. © 1987 Academic Press, Inc.
A general treatment of NMR imaging with chemical shifts and motion
Authors: Twieg Donald B. , Katz Jose , Peshock Ronald M. 
Published: March 2007

AbstractA general treatment of nuclear magnetic resonance imaging (MRI) and spectroscopic imaging (MRSI), which takes into account the effects of chemical shift, motion, field inhomogeneity, and relaxation times, is presented. A graphical representation based on the k trajectory formalism which includes these effects is then developed for MRI and MRSI acquisition processes. These considerations should be useful in the study and design of flow‐sensitive MRI and MRSI methods and the accurate prediction of motion artifacts in conventional MRI and MRSI techniques. We conclude by presenting examples illustrating applications of the general theory to specific MRSI and flow imaging methods. © 1987 Academic Press, Inc.
Lipid and water suppression by selective 1H homonuclear polarization transfer
Authors: Hardy Christopher J. , Dumoulin Charles L. 
Published: March 2007

AbstractA pulse sequence is presented which uses Polarization Transfer by a Selective Homo‐nuclear Technique (POTSHOT) to retain all resonances, in phase, from a selected coupled spin system while suppressing all other peaks, from both coupled and noncoupled spins. This technique, which is a selective form of Homonuclear Polarization Transfer (HPT), has been used in a 1.5‐T whole‐body system to generate edited 1H lactate spectra from lactate/oil phantoms and from excised dog hearts. © 1987 Academic Press, Inc.
Effects of age on apparent 31P spin–lattice relaxation times of rat brain phosphates
Authors: Stolk J. A. , Oolsen J. I. , Alderman D. W. , Schweizer M. P. 
Published: March 2007

AbstractApparent 31P spin–lattice relaxation times have been measured in vivo for brain phosphates in young adult, mature adult, and aged rats at 4.7 T and 35°C. Statistically significant differences were found for most phosphate species, except PCr and y‐ATP, among the three age groups, particularly between the young and mature adults. Age‐related changes in tissue composition and exchange reactions are discussed as possible contributors to these results. © 1987 Academic Press, Inc.
Spin echo imaging of multiple chemical shifts
Authors: Lohman J. A. B. , Ordidge R. J. , Connelly A. 
Published: March 2007

AbstractA method to obtain separate cross‐sectional NMR images of chemically different species on the basis of their difference in chemical shift is presented. The total experiment time is no longer than that required for a conventional image and the method retains the full sensitivity of a spin‐echo 2DFI imaging experiment. Simple addition of the chemical‐shift selective images produces an image free from chemical‐shift artifacts. Results of an in vivo experiment on a human subject are presented. © 1987 Academic press, Inc.
The design of a multiple inversion recovery sequence for T1 measurement
Authors: Young I. R. , Hall A. S. , Bydder G. M. 
Published: March 2007

AbstractInversion recovery has the potential to be a powerful method of determining the values of T1 in in vivo studies. However, because of its relative slowness it is not practical to undertake several experiments with different values of the interval between the magnetization inverting 180o pulse and the interrogating 90o one. The multiple inversion recovery method described here uses a series of sampling pulses, most much less than 90o, to produce a series of images. It is shown that slice shape is relatively reproducible from one sample to another and that, largely as a result, the accuracy of the sequence in measuring TI is encouraging. © 1987 Academic Press, Inc.
NMR changes in experimental allergic encephalomyelitis: NMR changes precede clinical and pathological events
Authors: O'brien J. T. , Noseworthy J. H. , Gilbert J. J. , Karlik S. J. 
Published: March 2007

AbstractIn guinea pigs immunized with myelin basic protein (MBP) in complete Freund's adjuvant, experimental allergic encephalomyelitis (EAE) shows a characteristic clinical and pathological course. This study characterized the proton nuclear magnetic resonance (NMR) properties of the central nervous system prior to the onset of clinical signs of EAE. At this time (Days 7–9), the blood brain barrier is disrupted. The effects of the injection of paramagnetic contrast agents gadolinium‐DTPA and gadolinium‐deferoxamine on the tissue NMR relaxation times were examined. Both proton T1 and T2 relaxation times were prolonged in the spinal cord and the brain prior to the onset of clinical and pathological changes. The largest change was in the thoracolumbar spinal cord where T2 prolongation was 22.9%. Gadolinium‐DTPA produced a moderate (5‐11%) or marked (9‐19%) decrease in control and MBP‐treated animals, respectively. Gadolinium‐deferoxamine also decreased proton relaxation times but was toxic to all animals, producing respiratory arrest. Changes in proton T2 relaxation times in cord and cerebellum were sufficiently large (> 10%) to suggest that they might be visualized by magnetic resonance imaging techniques. We have previously described the changes in proton relaxation times during the acute phase of EAE (S. J. Karlik, G. Strejan, J. J. Gilbert, and J. H. Noseworthy, Neurology 36, 1112 (1986)). This study indicates that proton relaxation times are significantly altered at a time when blood brain barrier disruption occurs prior to the onset of clinical or pathological signs. © 1987 Academic Press, Inc.
An optimized head coil design for MR imaging at 0.15 T
Authors: Marrocco Bernard J. D. , Drost Dick J. , Prato Frank S. 
Published: March 2007

AbstractReceive‐only head coils employing a modified solenoid design were developed for a 0.15‐T imager with horizontal main static and radiofrequency transmit fields. This coil design uses three or five identical horseshoe‐shaped elements, constructed of ½ outside diameter copper tubing, lying one above the other in equally spaced horizontal planes. Coils of this design were compared to the half‐saddle coil supplied with our imager and to the Hammersmith Hospital spherical coil (G. M. Bydder et al., J. Comput. Assist. Tomogr. 9, 987 (1985)). Compared to the half‐saddle coil, one of our new head coils has the same field of view while improving the signal‐to‐noise ratio (S/N) by 80% in the upper brain and 20% in the cervical vertebrae; compared to the spherical coil the S/N was up to 60% lower but the field of view was larger and patient comfort was better. © 1987 Academic Press, Inc.
Slice‐shape artifact changes with precession angle in rapid MR imaging
Authors: Young I. R. , Payne J. A. 
Published: March 2007

AbstractOne possible method of measuring TI in rapidly acquired magnetic resonance images using variants of the FLASH technique is by the manipulation of the magnetization precession angle. It is suggested here that this method is as prone to slice‐shape artifacts as many other approaches. © 1987 Academic Press, Inc.
Modified stimulated echo sequence for elimination of signals from stationary spins in MRI
Authors: Lahrech H. , Briguet A. , Graveron‐Demilly D. , Hiltbrand E. , Moran P. R. 
Published: March 2007

AbstractSimple modification of the basic stimulated echo sequence (MSTE), including bipolar gradient modulation, permits one to generate relative motion phase modulations between the two STE magnetization components. It is shown how this self‐referencing process can provide flow enhancement without combination of separated images. © 1987 Academic Press, Inc.
Rapid scan magnetic resonance angiography
Authors: Dumoulin C. L. , Souza S. P. , Hart H. R. 
Published: March 2007

AbstractThe change in phase of transverse spin magnetization induced by macroscopic spin motion in the direction of an applied magnetic field gradient is used to generate projection angiograms. The method can provide a quantitative measure of laminar and pulsatile flow. Cardiac synchronization is not required provided that data are acquired at many points in the cardiac cycle. The use of short TR and a large number of excitations provides better suppression of stationary tissue and patient motion artifacts than is possible with cardiac gated studies. In addition to improvements in image quality, a substantial shortening of Scan time is obtained. © 1987 Academic Press, Inc.
Transverse relaxation of saline and plasma using Mn(II), HSA–EDTA–Mn, and HSA–EDTA–Gd: Application to erythrocyte water exchange
Authors: Caines G. Herbert , Morgan Courtney F. , Long Robert C. , Goldstein J. H. 
Published: March 2007

AbstractEnhancements of 1H nuclear magnetic transverse relaxation rates by Mn(II)‐ and Gd(III)‐ethylenediaminetetraacetic acid (EDTA)‐human serum albumin (HSA) complexes are compared with MnCl2 in human plasma and isotonic saline. HSA–EDTA–Mn and HSA–EDTA–Gd in saline, at physiological concentrations of HSA, afforded T2's comparable to 2 mM MnCl2 in 4% HSA saline. The above reagents are new and potentially useful relaxation agents for the measurement of H2O exchange rates in erythrocyte suspensions. The exchange rate of water across the red cell membrane was determined using these new reagents over the temperature range from 20 to 37°C. © 1987 Academic Press, Inc.
23Na rotating frame imaging in the perfused rabbit heart using separate transmitter and receiver coils
Authors: Moonen C. T. W. , Anderson S. E. , Unger S. 
Published: March 2007

AbstractOne‐dimensional spatial localization of sodium absorption in the perfused rabbit heart was obtained using 23Na rotating frame imaging. A Dadok‐type coil was used as the receiver and a circular surface coil as the transmitter allowing regularly shaped slices and homogeneous reception sensitivity. The short time of spatial labeling in this technique results in minimal intensity losses due to relaxation processes. © 1987 Academic Press, Inc.
Localized imaging using stimulated echoes
Authors: Mills Pamela , Chew Wil , Litt Lawrence , Moseley Michael 
Published: March 2007

AbstractStimulated‐echo localized spectroscopy was combined with phase‐ and frequency‐encoding gradients to obtain “zoom” or magnified images of specific organsin situ. The technique requires neither surface coils nor an imaging coil arrangement that exclusively isolates the target organ. This technique can be readily applied to conventional spectrometer imagers that have limited computational capabilities. © 1987 Academic Press, Inc.
31P NMR spectroscopy of the stomach by zig–zag coil
Authors: Nakada Tsutomu , Kwee Ingrid L. , Miyazaki Toshiyuki , Iriguchi Norio , Maki Takeshi 
Published: March 2007

AbstractPhosphorus‐31 (31P) nuclear magnetic resonance (NMR) spectroscopic investigations of the rat stomach were performed utilizing a 1‐cm2, three‐turn, zig‐zag coil. A zig‐zag coil of this dimension produced an effective Bl field that extends only within a 4‐mm distance from the plane of the surface coil, rendering it possible to obtain high‐resolution 31P spectra localized to the stomach without contamination from surrounding tissues. Normal stomach showed a characteristic spectral pattern with resonances reflecting inorganic phosphate (Pi), phosphocreatine (PCr), and the α‐, β‐, and γ‐phosphates of adenosine triphosphate (ATP). Ischemia‐induced changes in Pi, PCr, and ATP resonances were readily followed in vivo with a time resolution of 2.13 min. Indomethacin‐induced ulcer revealed a low intracellular pH and a decrease in the PCr to Pi ratio indicating the partially ischemic conditions of ulcerative lesions of the stomach as has been previously suggested. The present studies indicate that 31P NMR spectroscopy utilizing a zig‐zag coil is a powerful tool to study local pathology of the gastrointestinal (GI) tract. Since zig‐zag coils suitable for fiberscopic devices are easily constructed, clinical applications of the present technique are apparent. © Academic Press, Inc.
Diabetes insipidus secondary to intracranial sarcoidosis confirmed by low‐field magnetic resonance
Authors: Lewis R. , Wilson J. , Smith F. W. 
Published: March 2007

AbstractA 32‐year‐old woman who had been diagnosed as having pulmonary sarcoidosis 18 months previously presented with thirst and polyuria. The diagnosis of diabetes insipidus was confirmed biochemically and magnetic resonance imaging (MRI) revealed sarcoid involvement of the pituitary stalk. © Academic Press, Inc.
A transformer‐coupled double‐resonant probe for NMR imaging and spectroscopy
Authors: Fitzsimmons Jeffrey R. , Brooker H. Ralph , Beck Barbara 
Published: March 2007

AbstractA new type of double‐resonant coil which takes advantage of the properties of a radio‐frequency transformer is described. Two concentric loops are wound in close proximity to yield a high mutual inductance. The primary side is tuned to 34 MHz for 31P and the secondary side is tuned to 85 MHz for protons. A single lead allows program control over frequency without the need to rearrange cabling. Proton and phosphorus spectroscopy are made possible over essentially the same volume of interest without the need for repositioning the sample. © Academic Press, Inc.
0.1‐T human fat/water separation by SIDAC
Authors: Manabe Atsutaka , Miyazaki Toshiyuki , Toyoshima Hideo 
Published: March 2007

AbstractHigh‐resolution human fat/water separated images were obtained in 17 min at a static magnetic field strength as low as 0.1 T. The sequence used was based on SIDAC (spectroscopic imaging by dephasing amplitude changing), which employs a stepwise changing dephase gradient for the separation of spectral and spatial information of magnetic spins. © Academic Press, Inc.
Instant images of the body by magnetic resonance
Authors: Richard Ian L. Pykett , Rzedzian R. 
Published: March 2007

AbstractProton magnetic resonance (MR) body images of the normal, adult human which have total scan times of typically only 40 ms per image are presented. There is no loss of spatial or contrast resolution due to motional blurring or ghosting; rather, movie loops of multiple 40‐ms images directly demonstrate normal respiratory and peristaltic motion. Manifestation of „traditional”︁ relaxation time contrast is demonstrated for a variety of spin echo (TE) and image repetition (TR) times. The images, obtained at 2.0 T on a new high‐speed MR system, have a signal‐to‐noise ratio for muscle of approximately 30:1 (TE = 30 ms) for a 4.7‐mm slice thickness (voxel size = 0.08 cm3). In a study presented as an example, 140 images covering the body from diaphragm to pelvis were all obtained within approximately 10 min. This method may help improve the efficacy of MR body imaging in general, and may play a role in applications which require high temporal resolution. © Academic Press, Inc.
Low‐power NMR volume selection by slicing z magnetization
Authors: Brereton Ian M. , Brooks William M. , Marshman Margaret F. , Field James , Doddrell David M. 
Published: March 2007

AbstractA novel method for reducing the rf power requirements of selective pulses employed for z magnetization slice inversion in localized NMR spectroscopy is presented. Following slice preparation by the use of frequency‐incremented sine pulses, the slice gradient is reduced, which narrows the frequency width of the slice. This allows the use of relatively low‐power selective inversion pulses, an important consideration for in vivo applications. © Academic Press, Inc.
A versatile multinuclear probe designed for in vivo NMR spectroscopy: Applications to subcutaneous human tumors in mice
Authors: Lyon Robbe C. , Tschudin Rolf G. , Daly Peter F. , Cohen Jack S. 
Published: March 2007

AbstractWe describe a versatile NMR probe that is designed for a variety of in vivo spectroscopic studies on small animals in vertical wide‐bore magnets. Replaceable brackets enable the coils to be exchanged readily in order to observe 1H, 13C, 31P, and other nuclei, and to carry out double‐resonance experiments. Two solenoidal coil designs are described and applied to observe 31P, 13C, and 1H natural abundance spectra of subcutaneously implanted human tumors in mice. For 31P and 31C observation with 1H decoupling, a concentric coil arrangement was employed with a broadband inner coil and the outer coil tuned to 1H at 400 MHz. A single coil tuned to 400 MHz was used to observe 1H resonances. A thin copper foil design was found to be superior with respect to S/N and resolution to previously described Faraday shields used to shield the NMR signals originating from nontumor tissues. 31P spectra of in vivo tumor tissue were compared to spectra of in vitro perfused tumor cells of the same origin. Tumor tissue in vivo exhibited much higher levels of inorganic phosphate and phosphocreatine. Signals from [13C2]glucose and its major metabolite, [13C2]lactate, were readily observed and monitored in an unobstructed region of the 13C spectra of tumor tissue in vivo following the injection of [13C2]glucose in adjacent tissues. A 1H spectrum of tumor tissue, characterized by five broad resonances, was observed with excellent water suppression. © 1988 Academic Press, Inc.
Noninvasive measurement of molar concentrations of 31P metabolites in vivo, using surface coil NMR spectroscopy
Authors: Tofts Paul S. , Wray Susan 
Published: March 2007

AbstractThe measurement of absolute concentration of 31P metabolites is described, using water 1H as an internal concentration standard. An analysis of the effect of variations in coil Q on flip angle and sensitivity is presented and verified experimentally. Concentrations of nucleoside triphosphate in rat brain and muscle have been measured. © 1988 Academic Press, Inc.
Magnetic field mapping
Authors: Hornak Joseph P. , Szumowski Jerzy , Bryant Robert G. 
Published: March 2007

AbstractHomogeneous radiofrequency magnetic fields are necessary for production of high‐quality magnetic images and for most forms of magnetic resonance spectroscopy. It is often convenient to map the radiofrequency homogeneity associated with a resonant device by measuring the magnetic image intensity of an aqueous phantom placed within the resonator. The rf field intensity is not related trivially to the magnetic image intensity, and the relationship is different for different image acquisition methods. In this report relationships between rf field intensity and magnetic image intensity are derived and radio‐frequency field maps presented for comparison using (1) an rf probe moved about within the resonant volume, (2) spin‐echo images, and (3) small tip angle gradient refocused echo images. © 1988 Academic Press, Inc.
Optimization of MR protocols: A statistical decision analysis approach
Authors: McVeigh Elliot R. , Bronskill Michael J. , Henkelman R. Mark 
Published: March 2007

AbstractA new method of optimizing MRI data acquisition protocols is presented. Tissues are modeled with probability density functions (PDFs) of tissue parameter values (such as T1, T2). The imaging data acquisition process is modeled as a mapping from a tissue parameter space to a signal strength space. Tissue parameter PDFs are mapped to signal strength PDFs for each tissue in a clinical problem. The efficacy of an MRI protocol is evaluated using the methods of statistical decision analysis applied to the signal strength PDFs, including the propagation of noise. This procedure evaluates the ability to discriminate different tissues based on the signal strengths produced with the protocol. The model can incorporate an arbitrary number of tissues, parameters, and pulse sequences in the protocol. The multivariate nature of MRI and the observed broad distribution of tissue parameter values makes this model more appropriate for optimizing data acquisition protocols than methods which maximize the signal‐difference‐to‐noise ratio between discrete values of the tissue parameters. It is shown that these two methods may calculate different optimal protocols. The method can be used to optimize data acquisition for quantitative computer‐based tissue classification, as well as imaging. Data acquisition and image processing philosophies are discussed in light of the method. © 1988 Academic Press, Inc.