bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of glycogen storage disease by in vivo13C NMR comparison of normal volunteers with a patient
Authors: Beckmann N. , Seelig J. , Wick H. 
Published: March 2007

AbstractBroadband proton‐decoupled natural abundance 13C spectra of the human calf. liver, and head were obtained from normal volunteers and a patient with glycogen type IIIA storage disease. Two concentric and coplanar surface coils of diameters 8.0 cm and 13.0 cm were used for 13C (at 16.0 MHz) and 'H (at 63.6 MHz), respectively. A WALTZ‐8 sequence lead to homogeneous decoupling over a large volume. In addition to lipid resonances a variety of other metabolite resonances could be resolved. The glycogen concentration in the muscle and the liver of normal volunteers varied considerably depending on dietary preparation and physical exercise. The glycogen level in the liver and the calf of a patient with glycogen type IIIA storage disease was increased by a factor of 2–3 compared to normal. well‐trained volunteers. Proton‐decoupled 13C spectra of human head are reported for the first time. The spectra are dominated by lipid resonances but an additional resonance at 54.0 ppm is clearly visible. The proton‐decoupled 13C head spectrum of a patient with glycogen type IIIA storage disease revealed additional resonances between 71.0 and 85.0 ppm. © 1990 Academic Press, Inc.
Noise correlations in data simultaneously acquired from multiple surface coil arrays
Authors: Hayes Cecil E. , Roemer Peter B. 
Published: March 2007

AbstractMultiple images acquired simultaneously from an array of surface coils can be combined to give a composite image with an improved signal‐to‐noise ratio (SNR) and a large field of view. The composite images' SNR can be optimized by taking advantage of noise correlations between coils and phase shifts induced by surface coil reception. Methods are derived for making optimal composite images with uniform noise or with uniform sensitivity. A simplified model is used to provide an intuitive understanding of the interaction of noise correlation and phase shift phenomena. © 1990 Academic Press, Inc.
The slotted crossover surface coil: A detector for in vivo NMR of skin
Authors: Nagel Timothy L. , Alderman Donald W. , Schoenborn Robin R. , Hendrickson Margo , Shelby Jane , Saffle Jeffrey , Schweizer Martin P. 
Published: March 2007

AbstractAn elongated, narrow, slotted crossover surface coil provides surface localization capable of resolving in vivo 31 P NMR spectra from skin tissues. The shallow B1 field penetration achieves localization objectives while the probe length maintains signal‐to‐noise requirements. Dielectric and inductive losses are minimized via the crossover design (see T. L. Nagel et al., Magn. Reson. Med. 13, xxx (1990). In vivo spectra with millimeter depth resolution were acquired in 5 min at 2 T without pulse localization sequences. Preliminary 31P NMR spectra of normal and thermally injured rat skin were completed using a 25 × 3‐mm slotted probe with a 3 × 2‐cm surface region of excitation. Normal rat skin tissue PCr/Pi ratios ranged from 3.8 to 4.7 for 5‐, 10‐, and 30‐γs pulse widths, while partial‐and full‐thickness scald injured tissues ranged from 0 to 2.8. Evaluation of a single minor partial thickness injury 1 to 5 h postburn shows evidence of a localized hypermetabolic response associated with hyperemia. Determination of bum depth and tissue viability appears feasible using: (1) PCr/Pi ratios and (2) observation of localized hypermetabolism. © 1990 Academic Press, Inc.
Hemodynamic and hepatic pH responses to sodium bicarbonate and carbicarb during systemic acidosis
Authors: Shapiro J. I. , Whalen M. , Chan L. 
Published: March 2007

AbstractRats subjected to ammonium chloride‐induced metabolic acidosis were given alkalinization therapy with either sodium bicarbonate or Carbicarb. Ammonium chloride‐induced Severe metabolic acidosis had minimal effect on mean arterial blood pressure and cardiac output. This acidosis resulted in a small but statistically significant fall in intracellular liver pH (pHi) as measured with 31P magnetic resonance spectroscopy (7.01 ± 0.05 vs 7.08 ± 0.04, p <0.05). Sodium bicarbonate treatment resulted in systemic alkalinization and increases in arterial pCO2 as well as transient but extreme decreases in cardiac output and mean arterial pressure. Alkalinization with sodium bicarbonate also resulted in a transient but significant decrease in intracellular liver pH (7.02 ± 0.06 at 5 min vs 7.09 f 0.06 at baseline, p <0.05). Carbicarb therapy resulted in systemic alkalinization without major changes in arterial pCO2, cardiac output, or mean arterial blood pressure. Moreover, Carbicarb effected a sustained intracellular alkalinization of the liver (pHi = 7.12 ± 0.07 at 5 min, p <0.05, pHi = 7.19 ± 0.07 at 10 min, p < 0.01, pHi = 7.16 ± 0.06 at 15 min, p <0.01, vs baseline pHi = 7.05 ± 0.06). These data suggest that Carbicarb may be a more effective buffer than sodium bicarbonate during conditions where ventilation is limited and hemodynamic instability is present. © 1990 Academic Press, Inc.
A high‐sensitivity, high‐B1 homogeneity probe for quantitation of metabolites
Authors: Hoult David I. , Deslauriers Roxanne 
Published: March 2007

AbstractAccurate quantitation of metabolites in biological samples of irregular shape and in‐homogeneous composition is generally acknowledged to be difficult. The difficulties are less pronounced with a probe having excellent B1 field homogeneity, high sensitivity, and a resonant frequency independent of sample size and composition. A prototype probe that aims to fulfill these requirements in wide‐bore horizontal magnets is described. It comprises four separate tuned rings on a spherical surface which give a B1 field that is flat to ±1% over the design volume. Inter‐ring coupling, and to a fifth ring used for matching, is by induction, and the mathematics of the tuning of the system are derived. It is shown that resonant frequency variation with sample size is negligible, and that the sensitivity closely approaches the theoretical limit. © 1990 Academic Press, Inc.
Phosphorus metabolites and the distribution of cell cycle phase of RIF‐1 tumors in response to 14 Gy irradiation
Authors: Majors Anthony W. , Ng Thian C. , Karalis Ipatia M. , Edinger Mark G. , Tubbs Raymond R. , Higgins Patrick D. , Shin Kyo H. 
Published: March 2007

AbstractSimultaneous measurements of DNA cell phase cycle distributions and in vivo 31P NMR spectroscopy were performed on 40 RIF‐1 murine tumors irradiated with 14 Gy of X‐radiation. Diploid and tetraploid tumor populations were observed. The cells blocked in G2/M phase were measured as a function of the ratios of tetraploid cell number in G2/ M phase versus total cell population measured. The G2/M population reached a maximum at 32 h post irradiation, dropping to control values by 72 h, while the ratio of inorganic phosphate to β‐nucleotide triphosphate dropped significantly at 32 h and remained significantly lower than control up to 72 h post irradiation. Measurements of PME, PDE, PCr, and pH showed no significant variations at any time point. No significant change in host cell population could be observed. Since the measured G2/M population never increased to more than 3% of the total cell population, the change observed in the 31P NMR spectra were not simply the result of possible differences in NMR profiles of the different cell phase populations but were more likely due to a change in the metabolic characteristics or environment of a majority of the Cells. © 1990 Academic Press, Inc.
The design of practical selective pulses for magnetic resonance imaging and spectroscopy using SPINCALC
Authors: Morris Peter G. , McIntyre Dominick J. O. , Rourke David E. , Ngo J. Thomas 
Published: March 2007

AbstractRecently, we introduced a new numerical approach to the design and optimization of NMR selective pulses, which we have christened “SPINCALC” (J. T. Ngo and P. G. Morris, Biochem. Soc. Trans. 14, 1271 (1986); J. T. Ngo and P. G. Morris, Magn. Reson. Med. 5, 217(1987)). The first practical application of pulses generated by SPINCALC is demonstrated on a standard 0.5‐T clinical MRI system. Results are shown for single phase π pulses suitable both for selective inversion and for selective refocusing. The extension of SPINCALC to multidimensional pulses is illustrated by the design of a two‐dimensional π pulse. © 1991 Academic Press, Inc.
Assignment of resonances in the 1H spectrum of rat brain by two‐dimensional shift correlated and j‐resolved NMR spectroscopy
Authors: Behar Kevin L. , Ogino Takashi 
Published: March 2007

AbstractTwo‐dimensional shift‐correlated (COSY) and J‐resolved NMR spectroscopy was used to identify and assign resonances in the aliphatic region (0.8 to 4.5 ppm) of the 1H spectrum of acid extracts and tissue of rat brain. The chemical shift and spin‐spin coupling constants of several resonances, which could not be resolved in one‐dimensional spectra of tissue, were determined. These properties, together with the appropriate multiplet structure and scalar coupling patterns observed in 2D J‐resolved and COSY spectra, were used to assign the resonances of lactate, threonine, alanine, γ‐amino butyrate, N‐acetyl aspartate, aspartate, glutamate, glutamine, taurine, and myo‐inositol. The single peak observed at 1.33 ppm in the ID 1H spectrum of excised brain tissue, which is generally assigned to lactate, was shown instead to consist of two overlapping peaks in 2D COSY contour plots. The intensity of both resonances increased considerably after death. The second resonance was assigned to threonine and the assignment was confirmed by ion‐exchange chromatography. Several cross peaks were identified in 2D COSY spectra of intact brain tissue that were not present in similar spectra of the acid extract. These nonmetabolite resonances were assigned to macromolecules. Analysis of 2D COSY contour plots in conjunction with 1D spectra revealed that the total creatine (creatine + phosphocreatine) resonance at 3.0 ppm was overlapped by both GABA and macromolecules. This macromolecule resonance was present in a 2D COSY spectrum of the rat brain obtained in situ with a surface coil following cardiac arrest, indicating that its presence in the 2D spectrum of excised brain tissue did not arise from tissue disruption. © 1991 Academic Press, Inc.
Yb‐DTPA, a novel contrast agent in magnetic resonance imaging: Application to rat kidney
Authors: Sarkar Susanta K. , Rycyna Robert E. , Lenkinski Robert E. , Solleveld Henk A. , Kinter Lewis B. 
Published: March 2007

AbstractWe have developed a novel contrast agent, ytterbium‐diethylenetriamine pentaacetic acid (Yb‐DTPA), for magnetic resonance imaging (MRI) and its mechanism of action is predominantly by the susceptibility mechanism. We have applied this contrast agent for renal MRI studies. We also demonstrate that Yb‐DTPA has a renal clearance similar to that of inulin in rats and may therefore be useful for the estimation of glomerular filtration rate. © 1991 Academic Press, Inc.
Application of Single‐Shot Spiral Scanning for Volume Localization
Authors: Ra J. B. , Rim C. Y. , Cho Z. H. 
Published: March 2007

AbstractA new technique using a spiral scan single‐shot RF pulse for localized volume selection has been developed and its experimental results are presented. This technique employs an additional radial‐gradient coil in conjunction with the oscillating gradients for the spiral scan to localize the 3D volume. The short selection time in this technique minimizes both signal contamination from unwanted regions and signal attenuation due to T2 decay. We provide both the theoretical background of the technique and the experimental results obtained from a phantom as well as a human volunteer. The proposed method appears simple and accurate in localizing a volume which would be used as either fast imaging or localized Spectroscopy. © 1991 Academic Press, Inc.
Analysis of 23Na NMR spectra from isolated perfused hearts
Authors: Kohler Susan J. , Perry Stanton B. , Stewart Laura C. , Atkinson David E. , Clarke Kieran , Ingwall Joanne S. 
Published: March 2007

AbstractThe 23Na NMR spectra obtained from isolated hearts perfused with buffer containing the paramagnetic shift reagent dysprosium triethylenetetraminehexaacetic acid, Dy(TTHA)3−, are complex and contain a number of overlapping peaks of different intensities. Spectra from rat, rabbit, guinea pig, and ferret hearts obtained during periods of control perfusion are similar and undergo similar changes when the hearts are subjected to periods of ischemia and reflow. The contributions from the intracellular, interstitial, vascular, and bath compartments to the multiple peaks in the spectra of rat hearts have been assigned. The significant contributions to these spectra of bulk magnetic susceptibility effects and incomplete mixing have been demonstrated through a series of modeling experiments. Since the spectra from hearts of different species are so similar, the peak assignments made for the rat are applicable to spectra from rabbit, guinea pig, and ferret hearts as well. This work provides a framework for quantitative analysis of the spectral changes which occur during conditions such as ischemia and reflow. © 1991 Academic Press. Inc.
Lipoproteins in heart transplantation: Proton magnetic resonance spectroscopy of plasma
Authors: Eugene Michel , Le Moyec Laurence , De Certaines Jacques , Desruennes Michèle , Le Rumeur Elisabeth , Fraysse Jean B. , Cabrol Christian 
Published: March 2007

AbstractDespite the major improvement in immunosuppressive therapy, noninvasive detection of heart graft rejection remains a challenge. As lipoproteins are involved in several immunomodulation mechanisms, we studied their proton NMR spectra in plasma from patients after heart transplantation. NMR data were compared to clinical and functional evaluation of rejection process. The total linewidths (TLW) of methyl and methylene peaks, mainly arising from lipoproteins, were significantly lower for patients without a rejection process than for patients before surgery and patients with evidences of a rejection process. When TLW values are referred to TLW on the 8th day for each patient, the sensitivity and the specificity of the test are increased, with resulting positive and negative predictive values of 90 and 9195, respectively. The results obtained on more than 400 samples from 46 patients justify the use of proton NMR spectroscopy as a clinical tool. © 1991 Academic Press. Inc.
Three‐dimensional MR microscopy with large arrays
Authors: Suddarth S. A. , Johnson G. A. 
Published: March 2007

AbstractMR microscopy of fixed specimens is described using large (2563) arrays. Images are acquired at 7.0 T with voxels as small as 70 × 70 × 70 μm (3.4 × 10−4 mm3), more than 25,000 times smaller than routine clinical body imaging. Separation of the acquisition, reconstruction, archival, and analysis onto networked workstations provides flexibility and efficiency in handling the large data sets. The isotropic data can be interactively displayed through any plane without loss of in‐plane resolution. The potential for applications of MR microscopy in clinical pathology is addressed. © 1991 Academic Press. Inc.
1H spectroscopic imaging using a spectral‐spatial excitation pulse
Authors: Spielman Daniel , Meyer Craig , Macovski Albert , Enzmann Dieter 
Published: March 2007

AbstractExcellent water suppression is required to perform in vivo 1H spectroscopic experiments. However water suppression is difficult due to both B0 and RF inhomogeneities. These inhomogeneities are particularly troublesome in spectroscopic imaging experiments where water suppression is required throughout some large region of interest. In this paper, we propose the use of spectral‐spatial excitation pulses for such experiments. These two‐dimensional pulses are shown to provide water suppression that is insensitive to a range of B0 and RF variations while simultaneously providing spatial localization. Experimental results including images (with voxel volumes ranging from 3.4 to 1.5 cc) of various brain metabolites from both a normal volunteer and a patient with a metastatic lung carcinoma are presented. © 1991 Academic Press. Inc.
Effect of differential saturation on the spatial localization performance of depth pulses
Authors: Michael David , Schleich Thomas 
Published: March 2007

AbstractComputer simulations of Depth pulse B (Θ(2Θ[±x, ±y])2; acquire) and other Depth pulses, verified by experimental surface coil NMR studies utilizing phantom samples, reveal that the spatial localization performance of Depth pulses degrades when the repetition time is short relative to T1 because of differential saturation, i.e., T1, discrimination effects. Simulations of Depth pulse A (Θ(2Θ[±x, ±y]); acquire) and Depth pulse B indicate that there is no phase‐cycled pulse sequence delivery order which negates the untoward effect of T1 discrimination on spatial localization performance. The results of this study demonstrate the importance of consistent magnetization preparation prior to the delivery of each phase‐cycled multiple pulse sequence in a Depth pulse cycle for obtaining optimal spatial localization performance. The untoward effects of inconsistent magnetization preparation, resulting from T1 discrimination, may be ameliorated by the application of many Depth pulse cycles. © 1991 Academic Press. Inc.
Spectroscopic imaging with multidimensional pulses for excitation: SIMPLE
Authors: Spielman Daniel , Pauly John , Macovski Albert , Enzmann Dieter 
Published: March 2007

AbstractProton spectroscopy and spectroscopic imaging in the human brain require the elimination of both water and lipid signals. Strong lipid signals from subcutaneous fat are usually eliminated by confining the excited volume to lie wholly within the skull. Water suppression, however, can be difficult due to both B0 and RF inhomogeneities, which are particularly troublesome in imaging experiments where a relatively large region‐of‐interest (ROI) is typical. In this paper, we discuss the use of multidimensional selective‐excitation pulses (e.g., pulses that are simultaneously selective along two axes) to both define the ROI and provide the necessary water suppression. Pulse sequences providing three‐dimensional localization along with water suppression that is insensitive to a range of B0 and RF inhomogeneities are described. Spectra and spectroscopic images (voxel volume = 3.4 cc, acquisition time = 38 min) of various 1H metabolites from a patient with an astrocytoma show clear differences between normal and cancerous tissues and demonstrate the ability of these techniques to be used in vivo.
In vivo measurements of bone marrow cellularity using volume‐localized proton NMR spectroscopy
Authors: Ballon D. , Jakubowski A. , Gabrilove J. , Graham M. C. , Zakowski M. , Sheridan C. , Koutcher J. A. 
Published: March 2007

AbstractVolume‐localized proton NMR spectroscopy was used to estimate bone marrow cellularity in the posterior iliac crests of patients undergoing treatment with hematopoietic growth factors for a variety of hematologic and neoplastic disorders. Twelve patients were accrued, six of whom were studied more than once, yielding a total of 25 measurements. These data were compared to cellularity assessments derived from conventional bone marrow core biopsies obtained within a 24‐h period before or after the NMR exam. The results obtained by the two methods are well correlated (R = 0.94, P < 0.001), suggesting that this noninvasive technique may preclude the need for biopsies in some cases. © 1991 Academic Press, Inc.
ACE: A single‐shot method for water‐suppressed localization and editing of spectra, images, and spectroscopic images
Authors: van Vaals J. J. , Bergman A. H. , den Boef J. H. , van den Boogert H. J. , van Gerwen P. H. J. 
Published: March 2007

AbstractA versatile method for localized (1H) NMR spectroscopy is presented. The method intrinsically combines B0‐based spatial localization with the possibility of water suppression and spectral editing. With this sequence it is feasible to localize not only single spectra but also phase‐encoded images and spectroscopic images. The technique essentially integrates the “Hahn spin‐echo” with the “stimulated echo” sequence and is therefore called ACE (acquiring combined echoes). It realizes water‐suppressed three‐dimensional localization in a single shot and can be used for localized shimming. Studies in which the new method is applied to phantoms with metabolites diluted at low concentrations are presented. Discrimination between lactate and alanine, employing an adapted spectral editing method with complete inversion, combined with simultaneous water suppression and localization of a 0.06‐cc volume is shown. The suppression of signals from outside the selected volume is a ⩾ 24,000. Also, the method is demonstrated by in vivo experiments at 6.3 T. Localized water‐suppressed 1H spectra are obtained completely noninvasively, leaving scalp and fur intact, from well‐defined volumes of 0.15 cc in the brain of a living rat. Water‐suppressed spectroscopic imaging over a localized volume with “body” coil excitation and noninvasive surface coil detection yielded spectra from voxels as small as 25 μl in the in vivo rat brain.
Diffusion and perfusion in high resolution NMR imaging and microscopy
Authors: Ahn C. B. , Chos Z. H. 
Published: March 2007

AbstractDiffusion and perfusion phenomena under strong gradient fields (∼100 G/cm) are examined in high resolution nuclear magnetic resonance (NMR) imaging and microscopy, where diffusion‐associated signal attenuation predominates over T1 and T2 relaxation decays. Image contrast based on the diffusion and microcirculation is discussed with experimental results obtained with a 7.0‐T microscopy system. Ultimate resolution limit due to diffusion is investigated in high resolution NMR imaging and microscopy. © 1991 Academic Press, Inc.
Dynamic imaging of contrast enhancement in brain tumors
Authors: Bullock P. R. , Mansfield P. , Gowland P. , Worthington B. S. , Firth J. L. 
Published: March 2007

AbstractGadolinium‐DTPA has been shown to be a good probe for demonstrating defects in the blood‐brain barrier, but it has a rapid rate of elimination so that peak circulating levels are short‐lived. In this study ultrafast echo‐planar imaging has been used in combination with a bolus injection of gadolinium‐DTPA to evaluate perfusion within brain tumors and to assess the degree of disruption of the blood‐brain barrier. The temporal profile of enhancement may allow discrimination between different tumor types. © 1991 Academic Press, Inc.
Fast Fourier projection for MR angiography
Authors: Napel Sandy , Dunne Shane , Rutt Brian K. 
Published: March 2007

AbstractWe have developed a technique called fast Fourier projection which rapidly produces projections through images and is particularly useful for generating MR angiograms. Based on the projection‐slice theorem of Fourier transform theory, this method extracts planes from three‐dimensional spatial frequency space and computes projections at arbitrary viewing angles by two‐dimensional inverse Fourier transformation. Typical computation times are on the order of 1 s per projection. This performance makes possible interactive selection of optimal projection directions for visualizing the desired vasculature in single or stereo‐pair angiographic images and drastically reduces the time required to generate sequences of projections for display in movie loops compared to the conventional ray‐casting approach. The method is easily implemented on off‐line workstations or directly on MRI computer systems. © 1991 Academic Press, Inc.