Abstract:
:In spin echo imaging, magnetization is assigned to a location defined by its frequency of rotation. In the presence of a static magnetic field inhomogeneity, however, this location does not correspond to the true location of the magnetization. This paper describes a magnetic resonance imaging technique called phase constrained encoding (PACE) that assigns magnetization to its true location through the use of a spin echo train and alternating readout gradients. Small artifactual side-bands occur in the point spread function but can be minimized or eliminated using higher gradient strengths, more echoes, and/or additional acquisitions. Implementation of a simple version of this technique confirms simulations.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Kim JK,Plewes DB,Henkelman RMdoi
10.1002/mrm.1910330407subject
Has Abstractpub_date
1995-04-01 00:00:00pages
497-505issue
4eissn
0740-3194issn
1522-2594journal_volume
33pub_type
杂志文章abstract::A multifocal mouse liver tumor model chemically induced with 5,9-dimethyl-7H-dibenzo[c,g]carbazole was investigated by respiratory-triggered morphological and functional MRI (fMRI) at 4.7 Tesla. The model is characterized by the presence of two tumor types: hypovascular cholangioma and vascularized hepatocellular carc...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10555
更新日期:2003-09-01 00:00:00
abstract:PURPOSE:Quantitative susceptibility mapping can be performed through the minimization of a function consisting of data fidelity and regularization terms. For data consistency, a Gaussian-phase noise distribution is often assumed, which breaks down when the signal-to-noise ratio is low. A previously proposed alternative...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27073
更新日期:2018-08-01 00:00:00
abstract::This study determines the accuracy and feasibility of using localized spin-lattice (T1) relaxation time measurements from magnetic resonance (MR) images to follow changes in extracellular/intracellular fluid ratios in defined subvolumes of living tissue. A red blood cell suspension was used as a test system and a simp...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910150107
更新日期:1990-07-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910370603
更新日期:1997-06-01 00:00:00
abstract::This work presents a method applied to the design of short self-shielded gradient coils of cylindrical geometry. The method uses a hybrid technique that combines the simulated annealing and target field methods to optimize the standard stream functions. The optimized stream functions were parameterized using a few deg...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/1522-2594(200103)45:3<505::aid-mrm1066>3.0
更新日期:2001-03-01 00:00:00
abstract::Formalin fixation of tissue is a common laboratory practice. A direct comparison of diffusion tensor imaging (DTI) parameters from mouse brains before (in vivo) and after (ex vivo) formalin fixation is reported herein. Five diffusion indices were examined in a cohort of seven mice: relative anisotropy (RA), directiona...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10605
更新日期:2003-10-01 00:00:00
abstract:PURPOSE:Dynamic phosphorus MR spectroscopic imaging (31 P-MRSI) experiments require temporal resolution on the order of seconds to concurrently assess different muscle groups. A highly accelerated pulse sequence combining flyback echo-planar spectroscopic imaging (EPSI) and compressed sensing was developed and tested i...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.27682
更新日期:2019-06-01 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::In rapidly acquired gradient echo images, lipid regions usually appear as areas of high signal intensity. In 2D inflow angiograms processed by the maximum intensity projection algorithm, this high lipid signal may prevent angiographic visualization of some blood vessels. We present a new approach to suppress the lipid...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910210110
更新日期:1991-09-01 00:00:00
abstract::Fucose is believed to be a marker for cancer that may be detectable by the 2D proton NMR (COSY) of human plasma. However, the COSY technique is time consuming and prone to error. These problems may be alleviated by using the SUPERCOSY pulse sequence; this technique shows that there are many other cross peaks in the re...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910150102
更新日期:1990-07-01 00:00:00
abstract::Using a 32-echo imaging pulse sequence, T2 relaxation decay curves were acquired from five white- and six gray-matter brain structures outlined in 12 normal volunteers. The water contents of white and gray matter were 0.71 (0.01) and 0.83 (0.03) g/ml, respectively. All white-matter structures had significantly higher ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910370107
更新日期:1997-01-01 00:00:00
abstract::High-quality, high-resolution, proton-decoupled natural-abundance 13C NMR spectra have been obtained in vitro at 100.6 MHz from unprocessed human pathology specimens of tumors and adjacent nonneoplastic control tissues from lung, colon, and prostate. In these preliminary studies, specific molecular parameters were ide...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910070403
更新日期:1988-08-01 00:00:00
abstract:PURPOSE:To achieve rapid, high resolution whole-brain gray matter (GM) imaging by developing a novel, single-slab three-dimensional dual-echo fast-spin-echo pulse sequence and GM-selective reconstruction. METHODS:Unlike conventional GM imaging that uses time-consuming double-inversion-recovery preparation, the propose...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26910
更新日期:2017-11-01 00:00:00
abstract::The study of lung perfusion in normal and diseased subjects is of great interest to physiologists and physicians. In this work we demonstrate the application of a liquid-phase hyperpolarized (HP) carbon-13 ((13)C) tracer to magnetic resonance imaging (MRI) of the pulmonary vasculature and pulmonary perfusion in a porc...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21168
更新日期:2007-03-01 00:00:00
abstract::The accuracy of the outcome in a diffusion tensor imaging (DTI) experiment depends on the acquisition scheme as well as the postprocessing methods used. In the present study, the DTI results acquired after applying different combinations of diffusion-weighted (DW) gradient orientations were initially compared. Then, s...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10046
更新日期:2002-02-01 00:00:00
abstract::Adipose tissue as well as other depots of fat (triglycerides) are increasingly being recognized as active contributors to the human function and metabolism. In addition to the fat concentration, also the fatty acid chemical composition (FAC) of the triglyceride molecules may play an important part in diseases such as ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章,评审
doi:10.1002/mrm.28471
更新日期:2021-01-01 00:00:00
abstract:PURPOSE:The goal of this study is to characterize and improve the accuracy of 2D magnetic resonance fingerprinting (MRF) scans in the presence of slice profile (SP) and B1 imperfections, which are two main factors that affect quantitative results in MRF. METHODS:The SP and B1 imperfections are characterized and correc...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26580
更新日期:2017-11-01 00:00:00
abstract::Wavelet packet analysis is a mathematical transformation that can be used to post-process images, for example, to remove image noise ("denoising"). At a very low signal-to-noise ratio (SNR <5), standard magnitude magnetic resonance images have skewed Rician noise statistics that degrade denoising performance. Since th...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199903)41:3<631::aid-mrm29
更新日期:1999-03-01 00:00:00
abstract:PURPOSE:To assess volumetric proton MR spectroscopic imaging (MRSI) of the human brain on multivendor MRI instruments. METHODS:Echo-planar spectroscopic imaging was developed on instruments from three manufacturers, with matched specifications and acquisition protocols that accounted for differences in sampling perfor...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25510
更新日期:2015-11-01 00:00:00
abstract::A method is presented that improves the effectiveness of RF-spoiling whenever an image consists of the averaging of several identical single acquisitions. Using this method, it becomes possible to reduce the necessary moment of the spoiler gradient by a factor equal to the number of averages. The idea is to perform th...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22882
更新日期:2011-10-01 00:00:00
abstract::Typically, MR-elastography (MRE) encodes the propagation of monochromatic acoustic waves in the MR-phase images via sinusoidal gradients characterized by a detection frequency equal to the frequency of the mechanical vibration. Therefore, the echo time of a conventional MRE sequence is typically longer than the vibrat...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22124
更新日期:2009-11-01 00:00:00
abstract::The absolute partial pressure of oxygen (pO(2)) in the mammary gland pad and femoral muscle of female mice was measured using EPR oximetry at 700 MHz. A small quantity of lithium phthalocyanine (LiPc) crystals was implanted in both mammary and femoral muscle tissue of female C3H mice. Subsequent EPR measurements were ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20714
更新日期:2005-12-01 00:00:00
abstract::In in vivo phosphorus magnetic resonance spectroscopy (MRS), spectroscopic imaging (SI) can be used as a flexible localization technique, producing spectra from multiple volumes in a single examination. Presented here are phosphorus SI studies of human organs in which a selective-volume SI reconstruction was used rath...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910120302
更新日期:1989-12-01 00:00:00
abstract:PURPOSE:T2 -weighted sequences are particularly sensitive to the radiofrequency (RF) field inhomogeneity problem at ultra-high-field because of the errors accumulated by the imperfections of the train of refocusing pulses. As parallel transmission (pTx) has proved particularly useful to counteract RF heterogeneities, u...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27001
更新日期:2018-07-01 00:00:00
abstract:PURPOSE:Direct mapping of neuronal currents using MRI would have fundamental impacts on brain functional imaging. Previous reports indicated that the stimulus-induced rotary saturation (SIRS) mechanism had the best potential of direct detection of neural oscillations; however, it lacked the high-sensitivity level neede...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25553
更新日期:2016-02-01 00:00:00
abstract::New algorithms for correlation analysis are presented that allow the mapping of brain activity from functional MRI (fMRI) data in real time during the ongoing scan. They combine the computation of the correlation coefficients between measured fMRI time-series data and a reference vector with "detrending", a technique ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(200002)43:2<259::aid-mrm13
更新日期:2000-02-01 00:00:00
abstract::Knowledge about the triglyceride (fat) (1)H spectrum enables quantitative determination of several triglyceride characteristics. This work describes a model-based chemical shift imaging method that separates water and fat signal and provides maps of three triglyceride quantities: fatty acid carbon chain length, unsatu...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24196
更新日期:2012-12-01 00:00:00
abstract:PURPOSE:Fluorescence lifetime imaging microscopy (FLIM) of endogenous fluorescent metabolites permits the measurement of cellular metabolism in cell, tissue and animal models. In parallel, magnetic resonance spectroscopy (MRS) of dynamic nuclear (hyper)polarized (DNP) 13 C-pyruvate enables measurement of metabolism at ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27644
更新日期:2019-05-01 00:00:00
abstract:PURPOSE:The purpose of the present study was to apply noninvasive methods for monitoring regeneration and mechanical properties of tissue-engineered cartilage in vivo at different growth stages using MR elastography (MRE). METHODS:Three types of scaffolds, including silk, collagen, and gelatin seeded by human mesenchy...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25745
更新日期:2016-03-01 00:00:00
abstract::Parallel excitation is being studied intensively for applications in MR imaging and in particular for selecting arbitrary shapes as regions of interest. In this work, parallel excitation was applied to arbitrarily shaped voxel selection in spectroscopy and investigated for different excitation k-space trajectories (ra...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.23018
更新日期:2012-02-01 00:00:00