Abstract:
:Some of the important features of how pulsatile flow generates artifacts in three-dimensional magnetic resonance imaging are analyzed and demonstrated. Time variations in the magnetic resonance signal during the heart cycle lead to more complex patterns of artifacts in 3D imaging than in 2D imaging. The appearance and location of these artifacts within the image volume are shown to be describable as displacements along a line in a plane parallel to that defined by the phase and volume encode directions. The angle of the line in the plane depends solely upon the imaging parameters while the ghost displacement along the line is proportional to the signal modulation frequency. Aliasing of these ghosts leads to a variety of artifact patterns which are sensitive to the pulsation period and repetition time of the pulse sequence. Numerical simulations of these effects were found to be in good agreement with experimental images of an elastic model of a human carotid artery under simulated physiological conditions and with images of two human subjects.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Frank LR,Buxton RB,Kerber CWdoi
10.1002/mrm.1910300305subject
Has Abstractpub_date
1993-09-01 00:00:00pages
296-304issue
3eissn
0740-3194issn
1522-2594journal_volume
30pub_type
杂志文章abstract::A non-invasive method for studying the modifications induced in lipid depots by hormonal stimulation could extend knowledge of adipose tissues. We studied the effect of adrenergic stimulation on interscapular brown adipose tissue (IBAT) of rats using contrast-enhanced MRI. Controls and rats pre-treated with adrenaline...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20851
更新日期:2006-04-01 00:00:00
abstract:PURPOSE:Magnetic resonance imaging of humans at high magnetic field strengths is strongly influenced by the interference of the radiofrequency (RF) electromagnetic field and the body. To minimize this effect, multiple RF sources could be used. A novel setup (called multimode, coaxial waveguide) is proposed that facilit...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24807
更新日期:2014-04-01 00:00:00
abstract::Brain water proton (1H2O) longitudinal relaxation time constants (T1) were obtained from three healthy individuals at magnetic field strengths (B0) of 0.2 Tesla (T), 1.0T, 1.5T, 4.0T, and 7.0T. A 5-mm midventricular axial slice was sampled using a modified Look-Locker technique with 1.5 mm in-plane resolution, and 32 ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21122
更新日期:2007-02-01 00:00:00
abstract::We constructed a device to compress small samples of articular cartilage while the samples were imaged in a 1.5 T imager. With the use of a piezoelectric piston, the device compressed 1-cm-diameter cylindrical samples of articular cartilage (200 microm) at a rate of 2 Hz. Simultaneously, we imaged the samples with a d...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20439
更新日期:2005-05-01 00:00:00
abstract:PURPOSE:To achieve artifact-suppressed whole-brain pass-band-balanced steady-state free precession functional MRI from a single functional magnetic resonance imaging (fMRI) scan. METHODS:A complete and practical data acquisition sequence for alt-SSFP fMRI was developed. First, multishot flyback-echo-planar imaging (EP...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25797
更新日期:2016-05-01 00:00:00
abstract:PURPOSE:This study aims to (i) develop a new high-speed MRI approach by implementing correlation imaging in wavelet-space, and (ii) demonstrate the ability of wavelet-space correlation imaging to image human anatomy with involuntary or physiological motion. METHODS:Correlation imaging is a high-speed MRI framework in ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25546
更新日期:2015-12-01 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::Passive MR tracking of catheters and guidewires is usually done by dynamically imaging a single thick slab, subtracting a baseline image, and combining the result with a previously acquired MR angiogram. In the in vitro and in vivo experiments reported here, it is demonstrated that this approach may be greatly simplif...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/1522-2594(200101)45:1<17::aid-mrm1003>3.0.
更新日期:2001-01-01 00:00:00
abstract::Generating flow-specific images (arteriograms, venograms) with optimal signal-to-noise ratios for time-resolved MR angiography is a conditional maximum problem, and its solutions are generalized matched filters. We have investigated six matched filters, corresponding to all possible combinations of three flow suppress...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910300511
更新日期:1993-11-01 00:00:00
abstract::The harmonic phase (HARP) method provides automatic and rapid analysis of tagged magnetic resonance (MR) images for quantification and visualization of myocardial strain. In this article, the development and implementation of a pulse sequence that acquires HARP images in real time are described. In this pulse sequence...
journal_title:Magnetic resonance in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/mrm.10509
更新日期:2003-07-01 00:00:00
abstract::Phase-sensitive inversion-recovery (PSIR) imaging may provide enhanced T(1) contrast. However, clinical implementation of PSIR imaging is hindered because image reconstruction with this method often lacks robustness and requires manual intervention, particularly for data acquired in multiple slices and with phased-arr...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20414
更新日期:2005-04-01 00:00:00
abstract::We exploit the intrinsic difference in magnetic resonance spin-spin relaxation time, T2, between water associated with myelin sheaths and water in other central nervous system tissue in order to measure myelin water content within any region of an image or to generate indirectly a myelin map of the brain. In normal vo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910310614
更新日期:1994-06-01 00:00:00
abstract::Calculations and experiments that provide support for our previously stated theorem are presented: If two coils simultaneously receiving magnetic resonance signals from the same anatomic region exhibit zero mutual inductance, there can be no correlation of the noise. It is shown that correlation does not exist even in...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910200105
更新日期:1991-07-01 00:00:00
abstract:PURPOSE:Anisotropic transverse R2 (1/T2 ) relaxation of water proton is sensitive to cartilage degenerative changes. The purpose is to develop an efficient method to extract this relaxation metric in clinical studies. METHODS:Anisotropic R2 can be measured inefficiently by standard R2 mapping after removing an isotrop...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27621
更新日期:2019-06-01 00:00:00
abstract:PURPOSE:Recent MRI studies have suggested that the magnetic susceptibility of white matter (WM) in the human brain is anisotropic, providing a new contrast mechanism for the visualization of fiber bundles and allowing the extraction of cellular compartment-specific information. This study provides an independent confir...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25524
更新日期:2015-11-01 00:00:00
abstract:PURPOSE:To develop methods for characterizing materials used in screen-printed MRI coils and improve signal-to-noise ratio (SNR) with new lower-loss materials. METHODS:An experimental apparatus was created to characterize dielectric properties of plastic substrates used in receive coils. Coils were fabricated by scree...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26399
更新日期:2017-08-01 00:00:00
abstract::To investigate white matter (WM) development, voxelwise analyses of diffusion tensor MRI (DTMRI) data, acquired from 12 very preterm and 11 preterm infants with gestational ages (GA) ranging from 25 to 29 and 29 to 32 weeks, respectively, and 10 newborn normal term infants were performed. T(2) relaxation measures were...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21689
更新日期:2008-10-01 00:00:00
abstract:PURPOSE:Lung pO2 mapping with (3)He MRI assumes that the sources of signal decay with time during a breath-hold are radiofrequency depolarization and oxygen-dependent T1 relaxation, but the method is sensitive to other sources of spatio-temporal signal change such as diffusion. The purpose of this work was to assess th...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24779
更新日期:2014-03-01 00:00:00
abstract::We describe a doubly tuned radiofrequency (RF) local coil probe designed specifically for performing in vivo image-localized spectroscopy. The probe was designed using principles developed in connection with the counter-rotating-current (CRC) and planar-pair loop gap resonators for magnetic resonance imaging (MRI). Th...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910060303
更新日期:1988-03-01 00:00:00
abstract::Image contrast with gradient-recalled echo sequences (GRE) used for fMRI can have both blood oxygen level-dependent (BOLD) and inflow components, and the latter is often undesirable. A dual-echo technique can be used to differentiate these mechanisms, because modulation of signal from inflow is common to both echoes, ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910350306
更新日期:1996-03-01 00:00:00
abstract::This study examines the effect of feature extraction methods prior to automated pattern recognition based on magnetic resonance spectroscopy (MRS) for brain tumor diagnosis. Since individual inspection of spectra is time-consuming and requires specific spectroscopic expertise, the introduction of clinical decision sup...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21626
更新日期:2008-08-01 00:00:00
abstract:PURPOSE:A MR thermometry (MRT) method with field monitoring is proposed to improve the measurement of small temperature variations induced in brain MRI exams. METHODS:MR thermometry experiments were performed at 7 Tesla with concurrent field monitoring and RF heating. Images were reconstructed with nominal k-space tra...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28501
更新日期:2021-03-01 00:00:00
abstract::Balanced steady-state free precession (SSFP) imaging is sensitive to off-resonance effects, which can lead to considerable artifacts during a transient phase following magnetization preparation or steady-state interruption. In addition, nonlinear k-space encoding is required if contrast-relevant k-space regions need t...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20615
更新日期:2005-10-01 00:00:00
abstract:PURPOSE:To obviate online slice-by-slice RF shim optimization and reduce B1+ mapping requirements for patient-specific RF shimming in high-field magnetic resonance imaging. THEORY AND METHODS:RF Shim Prediction by Iteratively Projected Ridge Regression (PIPRR) predicts patient-specific, SAR-efficient RF shims with a m...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27192
更新日期:2018-11-01 00:00:00
abstract:PURPOSE:Undiagnosed dehydration compromises health outcomes across many populations. Existing dehydration diagnostics require invasive bodily fluid sampling or are easily confounded by fluid and electrolyte intake, environment, and physical activity limiting widespread adoption. We present a portable MR sensor designed...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28004
更新日期:2020-04-01 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::An automated retrospective image registration based on mutual information is adapted to a multislice functional magnetic resonance imaging (fMRI) acquisition protocol to provide accurate motion correction. Motion correction is performed by mapping each slice to an anatomic volume data set acquired in the same fMRI ses...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199905)41:5<964::aid-mrm16
更新日期:1999-05-01 00:00:00
abstract::High-field MRI scanners are, in principle, well suited for mouse studies; however, many high-field magnets employ a vertical design that may influence the physiological state of the rodent. The purpose of this study was to investigate the orthostatic response of cerebral blood flow (CBF) in mice during a prolonged MR ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20621
更新日期:2005-10-01 00:00:00
abstract:PURPOSE:To use the variable delay multipulse (VDMP) chemical exchange saturation transfer (CEST) approach to obtain clean amide proton transfer (APT) and relayed Nuclear Overhauser enhancement (rNOE) CEST images in the human brain by suppressing the conventional magnetization transfer contrast (MTC) and reducing the di...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25990
更新日期:2016-01-01 00:00:00
abstract::To quantify metabolite and cation concentrations using NMR spectroscopy, the volumes of intracellular and extracellular spaces must be known. We describe a simple 31P NMR spectroscopic method that employs dimethyl methylphosphonate (DMMP) as a marker of total water space and phenylphosphonate (PPA) as a marker of extr...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910320206
更新日期:1994-08-01 00:00:00