bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of ultrasonography to evaluate muscle thickness and blood flow in free flaps
Authors: Salmi Asko , Ahovuo Juhani , Tukiainen Erkki , Härmä Markku , Asko‐Seljavaara Sirpa 
Published: March 2007

AbstractThe purpose of this study was to investigate the common belief that a microvascular transfer of a non‐innervated free muscle flap loses muscle bulk over time. Sixteen patients (latissimus dorsi = 8, rectus abdominis = 7, and gracilis muscle = 1) were evaluated an average of 41 months after free flap transfer. Latissimus dorsi and lower extremity flaps displayed significantly more swelling than the other flaps. Flap bulk was measured by ultrasound. The mean thickness of upper extremity flaps was 10.3 ± 1.8 mm (control muscles 11.8 ± 2.8), lower‐extremity 14.5 ± 3.7 mm (control muscles 10.9 ± 0.7), latissimus dorsi 14.3 ± 2.2 mm (control muscles 10.3 ± 0.8, P = 0.018), and rectus abdominis 11.2 ± 1.2 mm (control muscles 12.4 ± 1.9). Color Doppler ultrasonography was used to detect the pedicles of the free flaps and also to measure the peak velocity of blood flow intramuscularly and in the pedicles. In the upper extremities (n = 5) the pedicles could be found in only 20% of cases whereas in the lower extremities (n = 11) 91% of pedicles were located. (P = 0.013). Peak flow within the free flaps was significantly higher in the lower extremity (50% of the peak flow of the common femoral artery) than in the upper extremity (5% of the peak flow of the common femoral artery, P = 0.013). This study demonstrated that non‐innervated free muscle flaps in the extremities maintain the original muscle thickness, although lower extremity and latissimus dorsi flaps have a trend to be thicker. Most pedicles of free muscle flaps in the upper extremities could not be located by ultrasound. However, flaps in the lower extremities most often have patent pedicles and also more vigorous intramuscular blood flow. © 1995 Wiley‐Liss, Inc.
Composition and relaxation of the proton magnetization of human enamel and its contribution to the tooth NMR image
Authors: Funduk N. , Kydon D. W. , Schreiner L. J. , Peemoeller H. , Miljković L. , Pintar M. M. 
Published: March 2007

AbstractThe spin‐spin, T2, and spin‐lattice, T1, relaxation times and the magnetization of protons were measured in human enamel. The proton free induction decay was analyzed into solid‐like interstitial water, enamel apatite, and semiliquid‐like water components. The solid‐like interstitial water was evaluated to be ∼5 wt% and the semiliquid‐like water to be ∼1 to 2%. Neither in wet nor in dry natural enamel does the solid water exchange upon deuteration nor can it be extracted in vacuum. The semiliquid natural water, which is in the closed pores of the structure in the two samples above also remains unexchanged upon an 8 hr deuteration and connot be extracted in a vacuum. With the lineshape‐relaxation correlation NMR the free induction decays from heads and tails of the enamel rods were resolved. The solid‐like water with T2 of ∼14 m̈sec and the appatite with a T2 of ∼61 m̈sec have T2's too short to be observed in an NMR zeugmatogram. Therefore only the similiquid water component having an apparent T*2 of about 240 m̈sec would contribute ot the NMR image of human enamel. Since the relative intensity of this proton magnetization component in tooth in quite small the NMR image of tooth would show primarily the dentin and liquids within the tooth and on its surface.
A Parallel Algorithm for Rotating‐Frame Zeugmatography
Authors: Chen C.‐N. , Hoult D. I. , Sank V. J. 
Published: March 2007

AbstractAn algorithm, which utilizes a high degree of parallel processing, has been developed for two‐dimensional rotating‐frame zeugmatography so that a picture of 256 X 256 pixels can be generated with a minicomputer system 2 sec after data accumulation. An array processor is employed as a second processor and, the refresh memory of a display unit is used as a fast data storage entity. Approximately half the calculations are carried out in the array processor during the nuclear relaxation period. Data movement to and from the display memory occurs largely during, and in parallel with, the array processing. The sequence can be run at a repetition rate of 35 msec per free induction decay and the algorithm can be implemented in any two‐dimensional experiment of the Fourier transform genre.
The Installation of High‐Field NMR Equipment in a Hospital Environment
Authors: Bore Peter J. , Timms William E. 
Published: March 2007

AbstractInstalling high‐field magnets in hospital environments has implications for safety, for the performance of the equipment and for the well‐being of the subjects who will be examined. This paper outlines the relevant properties of magnets and identifies the requirements necessary for a safe and usable installation. One approach to the meeting of these requirements is described.
Analysis of multiple T2 proton relaxation processes in human head and imaging on the basis of selective and assigned T2 values
Authors: Gersonde K. , Felsberg L. , Tolxdorff T. , Ratzel D. , Ströbel B. 
Published: March 2007

AbstractTwo‐dimensional T2‐selective proton imaging of human head has been performed at 10 MHz employing Carr‐Purcell‐Gill‐Meiboom pulse trains with echo separation of 6 and 12 msec. Using the information of 36 spin echoes and applying a recovery time of 2 sec the magnetization decay has been traced. The multi‐exponential T2 relaxation curve of each pixel of the image has been deconvoluted into up to three monoexponential functions which are defined by 1/T2,i and αi. The T2,i values are represented in a T2 histogram of the slice and then selected for generating images which relate to protons with specific T2. The αi values indicate the relative amounts of the T2‐selected protons. Imaging on the basis of α2 values increases the contrast of the image. The multiple T2‐selective imaging technique leads to head images which show selectively cerebrospinal fluid, gray matter, different types of white matter, and nonassigned fast‐relaxing proton classes.
Proton magnetic relaxation in aqueous glycerol solutions containing manganese(II) Ion
Authors: Kennedy Scott D. , Bryant Robert G. 
Published: March 2007

AbstractThe proton nuclear magnetic relaxation rate, 1/T1, is reported as a function of d5‐ glycerol concentration for aqueous manganese(II) ion solutions over a range of magnetic field strengths corresponding to proton Larmor frequencies between 0.01 and 38 MHz. The data are analyzed in terms of the Solomon, Bloembergen, and Morgan equations which are found to be sufficient to account for the relaxation data over the field and concentration ranges studied. These data provide a useful reference for the viscosity dependence of manganese(II)‐ion‐induced magnetic relaxation in aqueous systems and a useful comparison with macromolecule bound manganese(II)‐ion‐induced relaxation where the theory is less successful.
Application of multipulse NMR to observe 13C‐labeled metabolites in biological systems
Authors: Bendall M. Robin , Hollander Jan A. Den , Arias‐Mendoza Fernando , Rothman Douglas L. , Behar Kevin L. , Shulman Robert G. 
Published: March 2007

AbstractLimitations in resolution and sensitivity of 13C NMR spectroscopy have reduced the information obtainable from intact biological systems. With the aim of increasing the information from in vivo 13C NMR two multipulse NMR techniques, the DEPT pulse sequence and the gated spin‐echo sequence, were used to obtain edited 13C NMR spectra from different 13C‐labeled mammalian tissues. This allowed the separation of the 13C NMR signals from the tissues into subspectra containing either CH, CH2, or CH3 signals, thereby increasing the information obtainable from these spectra. Comparing the two techniques, the DEPT sequence gives more accurate editing than the gated spin‐echo sequence but suffers from the difficulty of determining 1H pulse angles in vivo.
A versatile perfusion technique for metabolic studies by NMR
Authors: Geoffrion Yves , Lareau Sylvain , Deslauriers Roxanne , Butler Keith , Pass Michael , Smith Ian C. P. 
Published: March 2007

AbstractA perfusion technique applicable to metabolic studies by NMR is described in detail. The utility and versatility of the approach are demonstrated by following gluconeogenesis from [2‐13C]pyruvate in the perfused, isolated mouse liver, and lipogenesis from [2‐13C]acetate in perfused Acanthamoeba castellanii cells embedded in agarose filaments.
Significance of histopathology in pulsed NMR studies on cancer
Authors: Ranade S. S. , Bharade S. H. , Talwalkar G. V. , Sujata G. K. , Shrinivasan V. T. , Singh B. B. 
Published: March 2007

AbstractCharacterization of tissue by pulsed nuclear magnetic resonance spectrometry opened a new area of research. The differences in the NMR parameters T1 and T2 of normal and malignant tissues constitute the basis for their distinction by pulsed NMR spectrometry and also by NMR imaging in vivo. The present studies were undertaken to correlate the role of constituent histological elements encountered in various maligancy‐associated changes and T1 variations and are based on evaluation of samples taken from surgically resected specimens of carcinoma of the esophagus, comprising the uninvolved portions of the esophagus and the gastric end on gross examination. The uninvolved and involved regions showed low and high T1 values, respectively. High T1 values were also encountered in the zones of samples of uninvolved esophagus which histologically revealed areas with dysplasia. This feature, viz., dysplasia representing maligancyassociated changes, has been found to recur in many samples. Detailed histological studies provided further evidence confirming that areas with dysplasia contribute to an increase in T1 values whereas in zones at the gastric end metaplasia and hyperplasia are more common. The results are of value for demarcation of tumor area by in vivo NMR imaging.
Strategies and tactics in NMR imaging relaxation time measurements. I. Minimizing relaxation time errors due to image noise—the ideal case
Authors: Kurland Robert J. 
Published: March 2007

AbstractThe effect of NMR image noise on erros in calculated values of relaxation times is quantitatively assessed by use of relaxation time noise figures, which are derived on the basis of statistical principles as functions of pulse delay, repetition, and recovery intrvals for several types of pulse sequences. Two strategies for determining relaxation times are considered: two point (ratio of intensities for two experiments) and multipoint (least‐squares fit of intensities to pulse‐sequence functions for n experiments). For given total measurement times, values of pulse interval times are found which give minimum relaxation time noise figures. A comparison of ratio methods shows that the best is a combination saturation ‐recovery inversion‐recovery (SR/IR) technique. For short measurement times (less than about 10T1) this optimized SR/IR ratio determination is also superior to the best multipoint method, a series of inversion—recovery experiments with equally incremented inversion‐recovery times. An examination of the effect of signal averaging on the relaxation time noise shows that up to a measurement time characteristic of the particular method used (e. g., for times up to about 5T1 for the SR/IR ratio determination, 100T1 for the multipoint inversion‐recovery method), increased measurement time is more effectively allotted to longer pulse intervals than to signal averaging. Numerical examples are tabulated which can help one to set optimum values for pulse intervals, given a rough estimate of the relaxation time to be determined.
Proton Imaging with Surface Coils on a 0.15‐T Resistive System
Authors: Fitzsimmons Jeffrey R. , Thomas Ray G. , Mancuso Anthony A. 
Published: March 2007

AbstractCoil development is fundamental to the optimization of imaging systems at any field; however, it is especially critical for low‐field systems where signal strength is limited. Here we demonstrate a type of surface coil design which makes possible the acquisition of high‐quality images of the neck and extremities.
Chemical‐shift imaging using filtered back‐projection algorithms
Authors: Haselgrove John , Gilbert K. , Leigh J. S. 
Published: March 2007

AbstractA method of performing chemical‐shift imaging is described that avoids some of the disadvatages inherent in the techniques which use spin echos and phase encoding. A series of FIDs are recorded during the application of a series of static gradients and the spectral image is reconstructed using a conventional filtered back‐projection algorithm.
Chemical‐shift artifact correction scheme using echo‐time encoding technique
Authors: Cho Z. H. , Nalcioglu O. , Park H. W. , Ra J. B. , Hilal S. K. 
Published: March 2007

AbstractAn investigation has been undertaken to study the effects of chemical shift on NMR image obtained by the projection reconstruction technique. Mathematical simulation studies indicate that chemical shift causes blurring in NMR images regardless of the image reconstruction technique. A systematic study of such artifacts is presented and possible correction schemes are proposed. Exemplary results with and without correction of the chemical‐shift artifact and pulse schemes employed for projection reconstruction are presented. The present chemical‐shift correction scheme is basically the same as a spectroscopic imaging technique such as the existing 4‐D NMR imaging method except that the encoding steps required can be reduced substantially in the case of modest spectroscopic resolution.
In Vivo Nuclear Magnetic Resonance Imaging of Lithium
Authors: Renshaw Perry F. , Haselgrove John C. , Leigh John S. , Chance Britton 
Published: March 2007

AbstractMagnetic resonance imaging techniques have previously been applied to 1H, 23Na, 31P, and 19F nuclei. This is the first report of application of these techniques to 7Li. Lithium images of both aqueous phantoms and a rat abdomen are presented. Applications of this technique to humans are discussed.© 1985 Academic Press,Inc.
A Method for Chemical‐Shift‐Selective Imaging
Authors: Dumoulin Charles L. 
Published: March 2007

AbstractSelective suppression of a given resonance in an NMR image can be obtained with a π/2 pulse whose excitation spectrum in zero at the appropriate chemical shift. The selective π/2 pulse presented here is composed of two nonselective π/2 pulses of opposite phase. The two pulses are separated by a short interval which determines the excitation spectrum.© 1985 Academic Press,Inc.
The sectorial loop‐gap resonator for 31P NMR of the adult human liver at 1.5 t with surface tissue suppression
Authors: Jesmanowicz A. , Froncisz W. , Grist Thomas M. , Hyde James S. 
Published: March 2007

AbstractA new type of loop‐gap resonator, which because of its topology is called a “sectorial resonator,” is described in considerable analytical detail. It was used for 31P NMR of the livers of two human adult normal volunteers. An effective strategy for suppression of signals from surface tissue was developed. Depth selection was achieved using a separate excitation coil, permitting a reasonable degree of control of the shape of the sensitive region by adjustment of the dimensions of the excitation coil and of the type of pulse delivered. In addition a new principle for cancellation is described: the topology of the sectorial resonator leads to cancellation signals from tissue masses at the two openings of the structure. Using a phase‐altenated repeated 90° FID pulse sequence, good spectra were achieved in 2.5 min that are free from contamination by the phosphocreatine peak. © 1986 Academic Press, Inc.
Are quenches dangerous?
Authors: Bore P. J. , Galloway G. J. , Styles P. , Radda G. K. , Flynn G. , Pitts P. R. 
Published: March 2007

AbstractThere exists some uncertainty about the hazards which the quenching of a superconducting magnet would present to a subject undergoing an NMR examination. To investigate this problem, a 1.6‐T whole‐body magnet was quenched with an anesthetized pig lying in the bore. This paper reports our finding which, in the circumstances of this experiment, suggest that the risks are small. © 1986 Academic Press, Inc.
In vitro1H NMR “mapping” of human intervertebral discs
Authors: Furó I. , Bobest M. , Pócsik I. , Tompa K. 
Published: March 2007

AbstractHuman intervertebral discs were investigated by 1H NMR in vitro. The measured parameters of samples differently located in discs give the “maps” of discs. The spin‐lattice relaxation‐time maps show similar structure to dry matter and bound water maps, which might mean the future possibility to detect certain disc processes via accurate T1 images. © 1986 Academic Press, Inc.
The cryoprotective effects of dimethyl sulfoxide on human bone marrow as studied by 31P nuclear magnetic resonance spectroscopy
Authors: Brauer Manfred , Penney Heather F. , Janowska‐Wieczorek Anna , Sykes Brian D. 
Published: March 2007

Abstract31P nuclear magnetic resonance spectroscopy has been used to study freshly aspirated normal human bone marrow samples. The pH within the intact cells of the samples was determined from the chemical‐shift position of the resonance for inorganic phosphate within the cell; the intracellular pH was found to be 7.35 for fresh bone marrow. The chemical‐shift positions of the α and β phosphate resonances of adenosine 5′‐triphosphate were used to assess the fraction of this metabolite complexed with Mg2+. It was found that 84% of the total intracellular adenosine 5′‐triphosphate was in the Mg2+‐complexed form. The concentration of Mg2+ uncomplexed to any ligand was 0.4 mM. The areas of the resonances for the major phosphorus‐containing metabolites were used to determine intracellular concentrations. For fresh human bone marrow, the intracellular concentrations determined were phosphate monoesters < 0.3 mM, 2,3‐diphosphoglycerate 3.9 ± 1.0 mM, inorganic phosphate 1.2 ± 0.6 mM, phosphodiesters 2.8 ± 1.0 mM, adenosine 5′‐triphosphate 1.6 ± 0.4 mM, adenosine 5‐diphosphate < 0.2 mM, and nicotinamide adenine dinucleotide < 0.2 mM. These metabolite concentrations within the intact cell samples did not change over 2.0 h and changed only gradually over a 24‐h period. 31P nuclear magnetic resonance spectroscopy was then used to study the cryopreservation of normal human bone marrow in the presence of increasing concentrations of the penetrating cryopreservative dimethyl sulfoxide. Dimethyl sulfoxide alone without freezing was found to cause some gradual hydrolysis of 2,3‐diphosphoglycerate, presumably by stimulating diphosphoglycerate phosphatase. The effect of freezing human bone marrow to liquid nitrogen temperatures, storage, and rapid thawing was a dramatic fall in intracellular adenosine 5′‐triphosphate levels. The half‐life of the metabolite, after thawing, was about 0.3 h. If the bone marrow was frozen in the presence of 2.5, 5.0, and 7.5% dimethyl sulfoxide, the post‐thaw half‐life was prolonged to 0.4, 0.5, and 0.6 h, respectively. 15% dimethyl sulfoxide afforded complete cryoprotection, with adenosine 5′‐triphosphate levels constant for 15 h after thawing the human bone marrow. © 1986 Academic Press, Inc.
Application of anatomically shaped surface coils in MRI at 0.5 T
Authors: Doornbos J. , Grimbergen H. A. A. , Booijen P. E. , te Strake L. , Bloem J. L. , Vielvoye G. J. , Boskamp E. 
Published: March 2007

AbstractThe construction and application of eight different MRI surface coils is described. The coils consist of an anatomically shaped copper wire loop as an antenna and a printed circuit board containing electronic components for tuning and matching. The electronic device for tuning and matching is interchangeable between the various coils. Surface coils for signal detection yield images with high signal‐to‐noise ratio in comparison to the usual saddle‐shaped head or body coils. The sensitivity of a surface coil decreases with increasing distance between the coil and the object of interest and therefore the coils are constructed to fit the anatomical structure under examination as well as possible. The application of dedicated surface coils for superficial structures in the body extends the possibilities of the MRI system. Photographs of the coils positioned on the body and MR images of volunteers and patients are shown. © 1986 Academic Press, Inc.
Effects of antimalarial drugs on oxygen consumption by erythrocytes infected with Plasmodium berghei: An ESR study
Authors: Butler Keith W. , Deslauriers Roxanne , Smith Ian C. P. 
Published: March 2007

AbstractOxygen consumption in mouse erythrocytes infected with Plasmodium berghei has been followed by electron spin resonance (ESR) spectroscopy of nitroxide radical spin probes. The parasitized red cell suspension is mixed with the spin probe CTPO (3‐carbamoyl‐2, 2, 5, 5‐tetramethyl‐3‐pyrrolin‐1‐yloxy) in a closed chamber. Oxygen consumption is monitored by the increasing resolution of the superhyperfine splittings of the spin label. The antimalarial drugs quinacrine, primaquine, and quinine are shown to decrease the rate of oxygen consumption of the parasitized erythrocyte suspensions. The spin‐label method offers advantages over conventional polarographic and spectrophotometric assays for highly parasitized cell populations where cells are fragile and contain oxidized hemoglobin as well as hemoglobin‐derived pigments.
Echo shape analysis and image size adjustment on the level of echoes: Improvement of parameter‐selective proton images
Authors: Staemmler M. , Gersonde K. 
Published: March 2007

AbstractParameter‐selective imaging for tissue characterization is performed at low magnetic fields (0.24–0.28 T) employing echo trains with a large number of echoes (≦50), high‐power pulses, and the projection reconstruction method. Preprocessing of the raw echoes is important for the quality of the echo images which are the bases for further evaluation and generation of parameter‐selective images. Two new algorithms are implemented in the image preprocessing routine TOMIKON: Echo shape analysis and image size adjustment. Echo shape analysis allows the detection and the removal of spikes in the echo signals to avoid image artifacts. Image size adjustment is performed by expanding and contracting the time basis of the echoes resulting in a size normalization of the echo images, an indispensable condition for generating diffusion images. © 1986 Academic Press, Inc.
Present and future clinical position of magnetic resonance imaging
Authors: Steiner Robert E. 
Published: March 2007

AbstractFollowing the appearance of the first clinical reports on magnetic resonance imaging (MRI) five years ago, stock is now taken of the clinical value of this new imaging technique and its future potential is assessed. Contrast and spatial resolution as well as specificity of CT and MRI are compared and the multiplicity of sequences, multiplanar facility, and flexibility of MRI over CT are analyzed. The dominant role of MRI over CT in the study of some disorders of the central nervous system is assessed and so are the limitations. In this context the usefulness of paramagnetic contrast media is also evaluated. The difficulties of body imaging are discussed. The solutions of overcoming cardiac and respiratory motions artifacts are evaluated and areas where MRI has already achieved a high level of clinical application are identified. Mention is made of additional information obtainable by MRI as, for example, sodium imaging, blood flow measurements, and the combination of imaging with spectroscopy. Possible future prospects are analyzed, for example, high‐resolution imaging, alternative sequences to those commonly used in particular the short T1 IR se‐quence (STIR), chemical shift imaging, and the possibility of utilizing susceptibility for imaging purposes. The problem of radiofrequency receiver coil design is approached and so is the choice of magnetic fields. The future relationship of MRI with established non‐invasive techniques is stressed. © 1986 Academic Press, Inc.