Abstract:
:Hydrogen, sodium, and fluorine (added F-) NMR spectra of venous and oxygenated blood were measured. The fluorine resonance was seen as a single peak in both samples, and all three resonances exhibited the same deoxy-oxy shift. Because F- exchanges slowly across the red cell membrane, and because sodium is 95% extracellular, these results suggest that the intra-extracellular field difference delta B is less than 0.1 ppm. A small value of delta B tends to rule out transmembrane exchange as an important contributor to relaxation in MRI of blood and hematomas. However, the broadening of the resonances with deoxygenation, by 0.3-0.4 ppm, indicates that both intra- and extracellular gradients are of comparable and sufficient magnitude to produce the T2-weighted hypointensity seen in clinical magnetic resonance images of hematomas at high fields.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Brooks RA,Brunetti A,Alger JR,Di Chiro Gdoi
10.1002/mrm.1910120210subject
Has Abstractpub_date
1989-11-01 00:00:00pages
241-8issue
2eissn
0740-3194issn
1522-2594journal_volume
12pub_type
杂志文章abstract:PURPOSE:We investigated global specific absorption rate (SAR) and radiofrequency (RF) power requirements in parallel transmission as the distance between the transmit coils and the sample was increased. METHODS:We calculated ultimate intrinsic SAR (UISAR), which depends on object geometry and electrical properties but...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25646
更新日期:2016-01-01 00:00:00
abstract::Unusually high image contrast in vivo magnetic resonance imaging of the brain becomes observable at high magnetic fields when the blood oxygenation level is lowered. The cause of the contrast has been attributed to a magnetic susceptibility effect induced by paramagnetic deoxyhemoglobin in red cells. When the cylinder...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910160103
更新日期:1990-10-01 00:00:00
abstract:PURPOSE:To develop a 256-channel dense-array electroencephalography (dEEG) sensor net (the Ink-Net) using high-resistance polymer thick film (PTF) technology to improve safety and data quality during simultaneous dEEG/MRI. METHODS:Heating safety was assessed with temperature measurements in an anthropomorphic head pha...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26116
更新日期:2017-02-01 00:00:00
abstract:PURPOSE:Subendocardial dark-rim artifacts (DRAs) remain a major concern in first-pass perfusion (FPP) myocardial MRI and may lower the diagnostic accuracy for detection of ischemia. A major source of DRAs is the "Gibbs ringing" effect. We propose an optimized radial acquisition strategy aimed at eliminating ringing-ind...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24913
更新日期:2014-07-01 00:00:00
abstract::T2 relaxation time is a promising MRI parameter for the detection of cartilage degeneration in osteoarthritis. However, the accuracy and precision of the measured T2 may be substantially impaired by the low signal-to-noise ratio of images available from clinical examinations. The purpose of this work was to assess the...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22178
更新日期:2010-01-01 00:00:00
abstract:PURPOSE:The aim of this study was to compare prospective head motion correction and motion tracking abilities of two tracking systems: Active NMR field probes and a Moiré phase tracking camera system using an optical marker. METHODS:Both tracking systems were used simultaneously on human subjects. The prospective head...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27343
更新日期:2019-01-01 00:00:00
abstract::The potential application of gas microbubbles as a unique intravascular susceptibility contrast agent for MRI has not been fully explored. In this study, the MR susceptibility effect of an ultrasound microbubble contrast agent, Optison, was studied with rat liver imaging at 7 T. Optison suspension in two different dos...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20181
更新日期:2004-09-01 00:00:00
abstract::In proton magnetic resonance imaging (MRI) metallic substances lead to magnetic field distortions that often result in signal voids in the adjacent anatomic structures. Thus, metallic objects and superparamagnetic iron oxide (SPIO)-labeled cells appear as hypointense artifacts that obscure the underlying anatomy. The ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21399
更新日期:2007-11-01 00:00:00
abstract::Functional MRI (fMRI) by means of spin-echo (SE) techniques provides an interesting alternative to gradient-echo methods because the contrast is based primarily on dynamic averaging associated with the blood oxygenation level-dependent (BOLD) effect. In this article the contributions from different brain compartments ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20221
更新日期:2004-10-01 00:00:00
abstract::Quantitative artificial neural network analysis for 1550 ex vivo 31P nuclear magnetic resonance spectra from hypothermically reperfused pig livers was assessed. These spectra show wide ranges of metabolite concentrations and have been analyzed using metabolite prior knowledge based lineshape fitting analysis which had...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910380522
更新日期:1997-11-01 00:00:00
abstract::Experimental procedures for obtaining localized 31P NMR spectra of humans by means of the ISIS sequence are discussed in detail. The technique is optimized for use with volume coils and with surface coils in order to measure localized 31P NMR spectra of different tissues and organs. Selective frequency-modulated (FM) ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910110102
更新日期:1989-07-01 00:00:00
abstract::Image selected in vivo spectroscopy (ISIS) is a volume selection method often used for in vivo (31)P MRS, since it is suitable for measurements of substances with short T(2). However, ISIS can suffer from significant signal contributions caused by T(1) smearing from regions outside the VOI. A computer model was develo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/1522-2594(200010)44:4<546::aid-mrm8>3.0.co
更新日期:2000-10-01 00:00:00
abstract::Specialized receiver coils having a small sensitive region can provide an improvement in SNR for MR imaging and spectroscopy, at the expense of limiting the usable field of view. This work presents a technique for designing coil arrays that allows the size and location of the sensitive region to be selected remotely. ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910170128
更新日期:1991-01-01 00:00:00
abstract::A radiofrequency (RF) time-domain electron paramagnetic resonance (EPR) instrument operating at 300, 600, and 750 MHz was used to image tumor hypoxia with high spatial and temporal resolution. A high-speed signal-averaging Peripheral Component Interconnect (PCI) board with flexibility in the input signal level and the...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21194
更新日期:2007-04-01 00:00:00
abstract:PURPOSE:Diabetic nephropathy (DN) is the leading cause of renal failure; however, current clinical tests are insufficient for assessing this disease. DN is associated with changes in renal metabolites, so we evaluated the utility of chemical exchange saturation transfer (CEST) imaging to detect changes characteristic o...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26045
更新日期:2016-11-01 00:00:00
abstract:PURPOSE:To improve signal-to-noise ratio (SNR) for high-resolution spectroscopic imaging using a subspace-based technique known as SPectroscopic Imaging by exploiting spatiospectral CorrElation (SPICE). METHODS:The proposed method is based on a union-of-subspaces model of MRSI signals, which exploits the partial separ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26130
更新日期:2017-02-01 00:00:00
abstract::The differential effects of high temperature on 9L rat gliosarcoma cells cultured in two distinctive forms, namely, anchored monolayer cells and multicellular spheroids, were investigated using 31P nuclear magnetic resonance spectroscopy. The critical temperatures resulting in irreversible changes in cellular energeti...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910190233
更新日期:1991-06-01 00:00:00
abstract::The utility of MRI using magnetization transfer (MT) enhanced pulse sequences to diagnose hepatic cirrhosis in a rat model was investigated. Hepatic T1 was measured with and without MT off-resonance RF pulses in 17 treated and six control rats. The livers were evaluated histologically, and the hydroxyproline content q...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910310513
更新日期:1994-05-01 00:00:00
abstract::Assuming that the SSFP magnetization response maintains a steady state which is periodic in the presence of diffusion, we can solve for the diffusion effect in such sequences. Formulating a Fourier series decomposition solution to the Bloch-Torrey equation and imposing the steady-state condition, analytical expression...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910190209
更新日期:1991-06-01 00:00:00
abstract::This paper presents an improved data reconstruction method for generalized autocalibrating partially parallel acquisitions (GRAPPA) using multicolumn multiline interpolation (MCMLI). Both nearest acquired line (ky) neighboring points and column (kx) neighboring points from all components of an array coil were used to ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20601
更新日期:2005-09-01 00:00:00
abstract:PURPOSE:The aims of this study were (i) to establish a robust and fast method to quantify hepatocellular phosphorus compounds in molar concentration on a 3T clinical scanner, (ii) to evaluate its reproducibility, and (iii) to test its feasibility for a use in large cohort studies. METHOD:Proton-decoupled (31) P magnet...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24835
更新日期:2014-05-01 00:00:00
abstract::Manganese is a useful contrast agent for MRI of animals. Previously, it has been shown that systemic doses of MnCl(2) provide unique contrast in the rodent brain, enabling visualization of neuroarchitecture. The present work investigates the dose and temporal dependence of brain enhancement after i.v. administration o...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20368
更新日期:2005-03-01 00:00:00
abstract::Myocardial pH has been shown in animal models to be a sensitive indicator of ischemia. In vivo measurement in humans using 31p magnetic resonance spectroscopy is complicated by the overlap of blood 2,3-diphosphoglycerate peaks with the P(i) peak used for pH measurement. A "saturation transfer" method combined with spa...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199901)41:1<198::aid-mrm28
更新日期:1999-01-01 00:00:00
abstract::Levo-tetrahydropalmatine (l-THP) has shown significant promise in preclinical and clinical studies to treat drug addiction. Pharmacological MRI methods can elucidate the regional cerebral effects of l-THP, but there are potential confounds from the use of general anesthesia. To investigate the possible anesthetic-drug...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.23243
更新日期:2012-08-01 00:00:00
abstract:PURPOSE:The goal of this study was to measure and compare the apparent transverse relaxation time constants (T2 ) of five intracellular metabolites using localization by adiabatic selective refocusing (LASER) and point-resolved spectroscopy (PRESS) sequences in the human brain at 3 T. METHODS:Five healthy subjects wer...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26826
更新日期:2018-03-01 00:00:00
abstract::Surgical specimens from 22 patients with infiltrating ductal carcinoma of the breast were analyzed by high-resolution 1H NMR spectroscopy at 80 and 300 MHz. Results were compared with those obtained from 9 benign (proliferative dysplasia without atypia) breast samples. NMR spectra at 80 MHz showed well-resolved water ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910080407
更新日期:1988-12-01 00:00:00
abstract::Intermolecular double quantum coherences (iDQCs), signals that result from simultaneous transitions of two or more separated spins, are known to produce images that are highly sensitive to subvoxel structure, particularly local anisotropy. Here we demonstrate how iDQCs signal can be used to efficiently detect the anis...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21925
更新日期:2009-04-01 00:00:00
abstract::For time-resolved background-subtracted contrast-enhanced magnetic resonance angiography, the bright and sparse arterial signal allows unique identification of contrast bolus arrival in the arteries. This article presents an automatic filtering algorithm using such arterial characterization for selecting arterial phas...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10358
更新日期:2002-12-01 00:00:00
abstract::Magnetic resonance (MR) diffusion imaging is a useful technique with which to increase our understanding of pathologic damage to the central nervous system. To fully quantitate diffusion and anisotropy in the spinal cord, as in other tissues, it is necessary to determine the diffusion tensor. If spinal cord diffusion ...
journal_title:Magnetic resonance in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/(sici)1522-2594(200001)43:1<133::aid-mrm16
更新日期:2000-01-01 00:00:00
abstract::In in vivo (1)H spectroscopy, the signal at 1.32 ppm is usually assigned to lactate. This resonance position is shared with threonine at physiological pH. The similarity of spectral patterns of lactate and threonine renders the separate measurement of either threonine or lactate without and even with editing technical...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.21492
更新日期:2008-02-01 00:00:00