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 axis of a blood vessel is not parallel to the main magnetic field, the susceptibility difference produces varying local fields around the blood vessel. In gradient-echo images, not in spin-echo images, these local fields cause intravoxel dephasing of the water signal of the surrounding tissue. This description of the contrast enhancement has been confirmed by a series of in vitro blood sample experiments and image simulations. A predicted contrast change has been demonstrated in brain images of a mouse placed at two different orientations in the magnet. From the simulated images, the dependence of the contrast on the field strength has been estimated.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Ogawa S,Lee TMdoi
10.1002/mrm.1910160103subject
Has Abstractpub_date
1990-10-01 00:00:00pages
9-18issue
1eissn
0740-3194issn
1522-2594journal_volume
16pub_type
杂志文章abstract:PURPOSE:To determine the feasibility of employing the prior knowledge of well-separated chemical exchange saturation transfer (CEST) signals in the 9.4 T Z-spectrum to separate overlapping CEST signals acquired at 3 T, using a deep learning approach trained with 3 T and 9.4 T CEST spectral data from brains of the same ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27690
更新日期:2019-06-01 00:00:00
abstract:PURPOSE:To directly compare in vivo versus postmortem second-order motion-compensated spin-echo diffusion tensor imaging of the porcine heart. METHODS:Second-order motion-compensated spin-echo cardiac diffusion tensor imaging was performed during systolic contraction in vivo and repeated upon cardiac arrest by bariumc...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26871
更新日期:2018-04-01 00:00:00
abstract:PURPOSE:To assess the use of image registration for correcting respiratory motion in free breathing lung T1 mapping acquisition in patients with idiopathic pulmonary fibrosis (IPF). THEORY AND METHODS:The method presented used image registration to synthetic images during postprocessing to remove respiratory motion. S...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28342
更新日期:2020-12-01 00:00:00
abstract::Two-dimensional intersecting k-space trajectories have previously been demonstrated to allow fast multispectral imaging. Repeated sampling of k-space points leads to destructive interference of the signal coming from the off-resonance spectral peaks; on-resonance data reconstruction yields images of the on-resonance p...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21551
更新日期:2008-03-01 00:00:00
abstract::The goal of this work was to develop and evaluate a numerically optimized inversion pulse to be used with a homonuclear editing sequence to measure human cerebral GABA in vivo at 4.1 T in the occipital lobe. The optimized pulse was constructed using pallindromic symmetry with 30 pulses and 29 delays. The optimized pul...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910390103
更新日期:1998-01-01 00:00:00
abstract::Combined MRI and 3D spectroscopic imaging (MRI/3D-MRSI) was used to study the metabolic effects of hormone-deprivation therapy in 65 prostate cancer patients, who underwent either short, intermediate, or long-term therapy, compared to 30 untreated control patients. There was a significant time-dependent loss of the pr...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1159
更新日期:2001-07-01 00:00:00
abstract::Magnetic resonance imaging allows numerous k-space sampling schemes such as cartesian, polar, spherical, and other non-rectilinear trajectories. Non-rectilinear MR acquisitions permit fast scan times and can suppress motion artifacts. Still, these sampling schemes may adversely affect the image characteristics due to ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910360617
更新日期:1996-12-01 00:00:00
abstract:PURPOSE:To demonstrate the feasibility of mapping gas exchange with single breath-hold hyperpolarized (HP) 129 Xe in humans, acquiring parametric maps of lung physiology. The potential benefit of acceleration using parallel imaging for this application is also explored. METHODS:Six healthy volunteers were scanned with...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27765
更新日期:2019-09-01 00:00:00
abstract::Problems with in vivo proton spectroscopy include strong water and lipid signals, and the very complicated structures of the spectra. Multiple-quantum experiments can be designed to overcome these difficulties. Using a volume selective refocusing technique, one can demonstrate how multiple-quantum experiments can be p...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910060311
更新日期:1988-03-01 00:00:00
abstract::The use of the minimum stored energy current density map-based methodology of designing closed-bore symmetric superconducting magnets was described recently. The technique is further developed to cater for the design of interventional-type MRI systems, and in particular open symmetric magnets of the double-doughnut co...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22189
更新日期:2010-01-01 00:00:00
abstract:PURPOSE:To propose an explicit Balanced steady-state free precession (bSSFP) signal model that predicts eddy current-induced steady-state disruptions and to provide a prospective, practical, and general eddy current compensation method. THEORY AND METHODS:Gradient impulse response functions (GIRF) were used to simulat...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28097
更新日期:2020-07-01 00:00:00
abstract:PURPOSE:We incorporate simultaneous multislice (SMS) acquisition into MR fingerprinting (MRF) to accelerate the MRF acquisition. METHODS:The t-Blipped SMS-MRF method is achieved by adding a Gz blip before each data acquisition window and balancing it with a Gz blip of opposing polarity at the end of each TR. Thus the ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25799
更新日期:2016-05-01 00:00:00
abstract::Chemical shift-based multipoint water-fat separation methods have been applied in balanced steady-state free precession (bSSFP) sequences because of the high signal-to-noise-ratio (SNR) attainable. In this approach the echo formation is approximated to occur concurrently for both water and fat at an echo time (TE) equ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21303
更新日期:2007-08-01 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::The water proton resonance frequency (PRF) is temperature dependent and can thus be used for magnetic resonance (MR) thermometry. Since lipid proton resonance frequencies do not depend on temperature, fat suppression is essential for PRF-based temperature mapping. The efficacy of echo-shifted (TE > TR) gradient-echo i...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199907)42:1<53::aid-mrm9>3
更新日期:1999-07-01 00:00:00
abstract::High-field (>or=3 T) cardiac MRI is challenged by inhomogeneities of both the static magnetic field (B(0)) and the transmit radiofrequency field (B(1)+). The inhomogeneous B fields not only demand improved shimming methods but also impede the correct determination of the zero-order terms, i.e., the local resonance fre...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22234
更新日期:2010-02-01 00:00:00
abstract::Prepolarized MRI uses pulsed magnetic fields to produce MR images by polarizing the sample at one field strength (approximately 0.5 T) before imaging at a much lower field (approximately 50 mT). Contrast reflecting the T(1) of the sample at an intermediate field strength is achieved by polarizing the sample and then a...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20910
更新日期:2006-06-01 00:00:00
abstract::A receive-only phased-array coil was designed to image the lower extremities. The array consists of four volume coils placed on two cylindrical formers. The coil array has the ability to image both legs simultaneously over a 40 cm longitudinal field of view (FOV). Experiments using phantoms show an increase in signal-...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10712
更新日期:2004-03-01 00:00:00
abstract:PURPOSE:The correlation between glutamine metabolism and oncogene expression in cancers has led to a renewed interest in the role of glutamine in cancer cell survival. Hyperpolarized [5-(13) C]glutamine is evaluated as a potential biomarker for noninvasive metabolic measurements of drug response in prostate cancer cell...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25360
更新日期:2015-06-01 00:00:00
abstract::High-order radiofrequency transmitter coils are described that permit, in the context of NMR imaging, a knowledgeable trade-off between coil complexity and the degree of inhomogeneity over a specified volume of space. A mathematical formulation of high-order coils is developed for an axially symmetric polarizing dc fi...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910030108
更新日期:1986-02-01 00:00:00
abstract:PURPOSE:Recent literature shows that diffusion tensor properties can be estimated more accurately with diffusion kurtosis imaging (DKI) than with diffusion tensor imaging (DTI). Furthermore, the additional non-Gaussian diffusion features from DKI can be sensitive markers for tissue characterization. Despite these benef...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25165
更新日期:2015-02-01 00:00:00
abstract::Golgi impregnation is unique in its ability to display the dendritic trees and axons of large numbers of individual neurons by histology. Here we apply magnetic resonance microscopy to visualize the neuroanatomy of animal models by combining histologic fixation chemistry with paramagnetic contrast agents. Although the...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22322
更新日期:2010-05-01 00:00:00
abstract::Dynamic susceptibility contrast (DSC) MRI is now increasingly used for measuring perfusion in many different applications. The quantification of DSC data requires the measurement of the arterial input function (AIF) and the deconvolution of the tissue concentration time curve. One of the most accepted deconvolution me...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/1522-2594(200009)44:3<466::aid-mrm18>3.0.c
更新日期:2000-09-01 00:00:00
abstract::Fe(III)meso-tetra(4-sulfonatophenyl)porphine (Fe-TPPS4) has been investigated as a potential pH-sensitive nuclear magnetic resonance (NMR) proton image contrast agent. Relaxation rates (1/T1 and 1/T2) of water protons were measured as a function of pH and concentration of Fe-TPPS4 in phosphate-buffered isotonic saline...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910050313
更新日期:1987-09-01 00:00:00
abstract::Current implementations of coronary artery magnetic resonance angiography (MRA) suffer from limited coverage of the coronary arterial system. Whole-heart coronary MRA was implemented based on a free-breathing steady-state free-precession (SSFP) technique with magnetization preparation. The technique was compared to a ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10653
更新日期:2003-12-01 00:00:00
abstract::Quantitative cerebral tissue volumes may be useful for an objective assessment of pathological changes in brain. Accurate determination of tissue volumes is complicated, however, by the partial volume averaging (PVA) effect. We have, therefore, developed a new pulse sequence that minimizes the PVA through the use of i...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910390614
更新日期:1998-06-01 00:00:00
abstract:PURPOSE:To develop and evaluate a method for RF envelope correction without extra hardware or synchronization. METHODS:Transmitted RF waveforms are measured through a simple pulse sequence called the gradient reversal approach to evaluate RF (GRATER). The measured RF waveforms are used to compute predistorted RF wavef...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27930
更新日期:2020-01-01 00:00:00
abstract::The analysis of abdominal and thoracic dynamic contrast-enhanced MRI is often impaired by artifacts and misregistration caused by physiological motion. Breath-hold is too short to cover long acquisitions. A novel multipurpose reconstruction technique, entitled dynamic contrast-enhanced generalized reconstruction by in...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22644
更新日期:2011-03-01 00:00:00
abstract:PURPOSE:Spiral readouts combine several favorable properties that promise superior net sensitivity for diffusion imaging. The purpose of this study is to verify the signal-to-noise ratio (SNR) benefit of spiral acquisition in comparison with current echo-planar imaging (EPI) schemes. METHODS:Diffusion-weighted in vivo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28554
更新日期:2021-04-01 00:00:00
abstract::A novel multiple quantum filtering method is proposed that uses a doubly selective pulse termed Delays Alternating with Nutations for Tailored Excitation (DANTE) for multiple quantum preparation. This method selectively prepares GABA-3 and GABA-4 into a multiple quantum state and suppresses all other resonances at 3.0...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10104
更新日期:2002-03-01 00:00:00