Abstract:
:The authors introduce several sets of time-efficient gradient waveforms for applying isotropic diffusion weighting in NMR experiments. This creates signal attenuation that depends on the trace of the diffusion tensor and is therefore rotationally invariant. Numerical methods for the calculation of such gradient sets are outlined, and results are shown for isotropic and anisotropic gradient hardware and first order flow moment nulled diffusion weighting gradients. Preliminary experimental results from the human brain validate this new technique.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Wong EC,Cox RW,Song AWdoi
10.1002/mrm.1910340202subject
Has Abstractpub_date
1995-08-01 00:00:00pages
139-43issue
2eissn
0740-3194issn
1522-2594journal_volume
34pub_type
杂志文章abstract::A new method for efficiently processing MRS data acquired with phased-array coils is presented. The method consists of performing phase compensation (i.e., redefining the signal phase relative to a common reference) of the signals in the time domain prior to combining the signals. The resulting spectra are equivalent ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20244
更新日期:2004-11-01 00:00:00
abstract:PURPOSE:To obtain whole-brain high-resolution T2 maps in 2 minutes by combining simultaneous multislice excitation and low-power PINS (power independent of number of slices) refocusing pulses with undersampling and a model-based reconstruction. METHODS:A multi-echo spin-echo sequence was modified to acquire multiple s...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27890
更新日期:2019-12-01 00:00:00
abstract::Optimization of experimental settings of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), like the contrast administration protocol, is of great importance for reliable quantification of the microcirculatory properties, such as the volume transfer-constant K(trans). Using system identification theory an...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21575
更新日期:2008-05-01 00:00:00
abstract::An eight-channel receive-only brain coil and table-top detunable volume transmit coil were developed and tested at 7 T for human imaging. Optimization of this device required attention to sources of interaction between the array elements, between the transmit and receive coils and minimization of common mode currents ...
journal_title:Magnetic resonance in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/mrm.20547
更新日期:2005-07-01 00:00:00
abstract::The clinical application of 3D proton spectroscopic imaging (3D SI) of the human prostate requires a robust suppression of periprostatic lipid signal contamination, minimal intervoxel signal contamination, and the shortest possible measurement time. In this work, a weighted elliptical sampling of k-space, combined wit...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20103
更新日期:2004-07-01 00:00:00
abstract:PURPOSE:Accurate characterization of contrast reagent (CR) longitudinal relaxivity in whole blood is required to predict arterial signal intensity in contrast-enhanced MR angiography (CE-MRA). This study measured the longitudinal relaxation rate constants (R1 ) over a concentration range for non-protein-binding and pro...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25064
更新日期:2014-12-01 00:00:00
abstract::The effects of reducing the pulse repetition time from 2500 ms to 1000 ms when using spin-density-projection-assisted R2-magnetic resonance imaging for the purpose of measuring liver iron concentration were evaluated. Repeated liver R2 measurements were made using both protocols on 60 subjects with liver iron concentr...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22712
更新日期:2011-05-01 00:00:00
abstract:PURPOSE:To demonstrate how triple diffusion encoding (TDE) MRI can be applied to separately estimate the intra-axonal and extra-axonal diffusion tensors in white matter (WM). METHODS:Using a TDE pulse sequence with an axially symmetric b-matrix, diffusion MRI data were acquired at 3T for 3 healthy adults with an axial...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28084
更新日期:2020-06-01 00:00:00
abstract::It is demonstrated that a high-resolution (1)H NMR spectrum of excised rat liver can be obtained using the technique of magic angle turning (MAT) at a sample spinning rate of 1 Hz. A variant of the phase-corrected MAT (PHORMAT) pulse sequence that includes a water suppression segment was developed for the investigatio...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10139
更新日期:2002-05-01 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: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 develop a framework for respiratory motion-corrected 3D whole-heart water/fat coronary MR angiography (CMRA) at 3T with reduced and predictable scan time. METHODS:A 3D dual-echo acquisition and respiratory motion-corrected reconstruction framework for water/fat CMRA imaging was developed. The acquisition se...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27732
更新日期:2019-08-01 00:00:00
abstract:PURPOSE:To test octafluorocyclobutane (OFCB) as an inhalation contrast agent for fluorine-19 MRI of the lung, and to compare the image quality of OFCB scans with perfluoropropane (PFP) scans THEORY AND METHODS: After normalizing for the number of signal averages, a theoretical comparison between the OFCB signal-to-nois...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28473
更新日期:2021-02-01 00:00:00
abstract::The combination of cardiac viability and functional information enhances the identification of different heart tissues in the setting of ischemic heart disease. A method has recently been proposed for obtaining black-blood delayed-enhancement (DE) viability images using the stimulated-echo acquisition mode (STEAM) MRI...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21390
更新日期:2007-10-01 00:00:00
abstract::Longitudinal P-31 relaxation rate enhancements of phosphate groups have been measured at pH 7-7.2 and 310 degrees K on aqueous solutions containing adenosine triphosphate (ATP), phosphocreatine (PCr), inorganic phosphate (Pi) and some lanthanide complexes (Gd-DOTA, Gd-HPDO3A, Gd-DO3A, Gd-DTPA, Gd-DTPA-BMA). The macroc...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910310413
更新日期:1994-04-01 00:00:00
abstract::The effects of macroscopic background field gradients upon 2D gradient echo images of inhaled (3)He in the human lung were investigated at 1.5 T. Effective compensation of in-slice signal loss in (3)He gradient echo images was then demonstrated using a multiple acquisition interleaved single gradient echo sequence. Th...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10549
更新日期:2003-08-01 00:00:00
abstract:PURPOSE:Correlation imaging is a previously developed high-speed MRI framework that converts parallel imaging reconstruction into the estimate of correlation functions. The presented work aims to demonstrate this framework can provide a speed gain over parallel imaging by estimating k-space variant correlation function...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26818
更新日期:2018-03-01 00:00:00
abstract::Image reconstruction of tagged cardiac MR images using complementary spatial modulation of magnetization (CSPAMM) requires the subtraction of two complex datasets to remove the untagged signal. Although the resultant images typically have sharper and more persistent tags than images formed without complementary taggin...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10523
更新日期:2003-08-01 00:00:00
abstract::Parallel imaging based on generalized autocalibrating partially parallel acquisitions is widely used in the clinical routine. To date, no detailed analysis has been presented describing the dependence of the image quality on the reconstruction and acquisition parameters such as the number of autocalibration signal (AC...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22803
更新日期:2011-08-01 00:00:00
abstract::Quantitative magnetization transfer imaging yields indices describing the interactions between free water protons and immobile, macromolecular protons-including the macromolecular to free pool size ratio (PSR) and the rate of magnetization transfer between pools k(mf) . This study describes the first implementation of...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22928
更新日期:2011-11-01 00:00:00
abstract::Measuring T(2) at 7.0 T is not trivial due to RF inhomogeneity effects, however, gradient echo sampling of a spin echo is insensitive to RF pulse errors, does not suffer from significant distortions, and allows T'(2) and T(2) to be estimated simultaneously. Gradient echo sampling of a spin echo results are relatively ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22522
更新日期:2010-11-01 00:00:00
abstract::Hyperpolarized gases ((129)Xe and (3)He) are being used increasingly in both MRI and NMR spectroscopy studies. However, it has been shown that carrier agents are required to preserve the long relaxation times of gases in biological fluids. Optimized gas transport can be achieved through controlled T(1) and T(2) measur...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10476
更新日期:2003-06-01 00:00:00
abstract::In this study we utilized manganese-enhanced MRI (MEMRI) to evaluate the in vivo transneuronal efficiency of manganese ion (Mn(2+)) movement as a means to assess overall changes in neuronal function. We designated this extension the manganese transfer index (MTI) value. To evaluate the MTI value as an index of transne...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21648
更新日期:2008-07-01 00:00:00
abstract:PURPOSE:MR fingerprinting (MRF) is a technique for quantitative tissue mapping using pseudorandom measurements. To estimate tissue properties such as T1 , T2 , proton density, and B0 , the rapidly acquired data are compared against a large dictionary of Bloch simulations. This matching process can be a very computation...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25439
更新日期:2015-08-01 00:00:00
abstract::A method is demonstrated for detection of magnetization from a selected region within the sensitive volume of a surface coil in a single acquisition. Composite pulses are described which eliminate signals from regions where magnetization is rotated 270 and 450 degrees. There is a loss of 1.3% or less of signal from re...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910030221
更新日期:1986-04-01 00:00:00
abstract::The incoherent displacement of water in living tissues is of considerable interest because of the widespread use of diffusion-weighted MRI, for which image contrast is based on the water apparent diffusion coefficient (ADC). It has been hypothesized that the decrease in water ADC associated with brain injury is primar...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10181
更新日期:2002-07-01 00:00:00
abstract:PURPOSE:To investigate the influence of transcytolemmal water exchange on estimates of tissue microstructural parameters derived from diffusion MRI using conventional PGSE and IMPULSED methods. METHODS:Computer simulations were performed to incorporate a broad range of intracellular water life times τin (50-∞ ms), cel...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26309
更新日期:2017-06-01 00:00:00
abstract::With standard spectroscopic imaging, high spatial resolution is achieved at the price of a large number of phase-encoding steps, leading to long acquisition times. Fast spatial encoding methods reduce the minimum total acquisition time. In this article, a k-space scanning scheme using a continuous series of growing an...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10622
更新日期:2003-12-01 00:00:00
abstract::Accumulation of lipids in atherosclerotic plaques causes progressive narrowing of the arterial lumen, often followed by thrombosis and ischemia. Currently several different methods, most requiring disruption of the plaque, are used to study the physical properties of lipids accumulated in plaques, and lipid compositio...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910390204
更新日期:1998-02-01 00:00:00
abstract::We 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 solenoid...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910060102
更新日期:1988-01-01 00:00:00