Abstract:
PURPOSE:Cross-term spatiotemporal encoding (xSPEN) is a single-shot approach with exceptional immunity to field heterogeneities, the images of which faithfully deliver 2D spatial distributions without requiring a priori information or using postacquisition corrections. xSPEN, however, suffers from signal-to-noise ratio penalties due to its non-Fourier nature and due to diffusion losses-especially when seeking high resolution. This study explores partial Fourier transform approaches that, acting along either the readout or the spatiotemporally encoded dimensions, reduce these penalties. METHODS:xSPEN uses an orthogonal (e.g., z) gradient to read, in direct space, the low-bandwidth (e.g., y) dimension. This substantially changes the nature of partial Fourier acquisitions vis-à-vis conventional imaging counterparts. A suitable theoretical analysis is derived to implement these procedures, along either the spatiotemporally or readout axes. RESULTS:Partial Fourier single-shot xSPEN images were recorded on preclinical and human scanners. Owing to their reduction in the experiments' acquisition times, this approach provided substantial sensitivity gains vis-à-vis previous implementations for a given targeted in-plane resolution. The physical origins of these gains are explained. CONCLUSION:Partial Fourier approaches, particularly when implemented along the low-bandwidth spatiotemporal dimension, provide several-fold sensitivity advantages at minimal costs to the execution and processing of the single-shot experiments. Magn Reson Med 79:1506-1514, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Zhang Z,Frydman Ldoi
10.1002/mrm.26824subject
Has Abstractpub_date
2018-03-01 00:00:00pages
1506-1514issue
3eissn
0740-3194issn
1522-2594journal_volume
79pub_type
杂志文章abstract:PURPOSE:To demonstrate the feasibility of imaging the first passage of a bolus of hyperpolarized (13)C urea through the rodent heart using flow-sensitizing gradients to reduce signal from the blood pool. METHODS:A flow-sensitizing bipolar gradient was optimized to reduce the bright signal within the cardiac chambers, ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25713
更新日期:2016-04-01 00:00:00
abstract:PURPOSE:Real-time assessment of ventricular volumes requires high acceleration factors. Residual convolutional neural networks (CNN) have shown potential for removing artifacts caused by data undersampling. In this study, we investigated the ability of CNNs to reconstruct highly accelerated radial real-time data in pat...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27480
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abstract:PURPOSE:To design, construct, and evaluate quantitative MR phantoms that mimic MRI signals from the liver with simultaneous control of three parameters: proton-density fat fraction (PDFF), R 2 ∗ ...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.28452
更新日期:2021-02-01 00:00:00
abstract::For diffusion-weighted magnetic resonance imaging and under circumstances where patient movement can be modeled as rigid body motion, it is shown both theoretically and experimentally that translations and rotations produce phase errors which are zero- and first-order, respectively, in position. While a navigator echo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910320313
更新日期:1994-09-01 00:00:00
abstract::Advances in modern magnetic resonance imaging (MRI) pulse sequences have enabled clinically practical cortical bone imaging. Human cortical bone is known to contain a distribution of T(1) and T(2) components attributed to bound and pore water, although clinical imaging approaches have yet to discriminate bound from po...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.24186
更新日期:2012-12-01 00:00:00
abstract::A modified high-speed stimulated-echo acquisition mode (STEAM) diffusion sequence (90 degrees-TE/2-90 degrees-TM-[alpha-TE/2-STE]n) incorporating bipolar diffusion gradients that are less sensitive to macroscopic motion-induced artifacts is presented. Diffusion encoding was performed only during the first echo interva...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.1910350620
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abstract::Chemical exchange saturation transfer (CEST), arterial spin labeling (ASL), and magnetization transfer contrast (MTC) methods generate different contrasts for MRI. However, they share many similarities in terms of pulse sequences and mechanistic principles. They all use RF pulse preparation schemes to label the longit...
journal_title:Magnetic resonance in medicine
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更新日期:2018-10-01 00:00:00
abstract:PURPOSE:To establish a cardiac signal from scattering matrix or scattering coefficient measurements made on a 7T 8-channel parallel transmit (pTx) system, and to evaluate its use for cardiac gating. METHODS:Measurements of the scattering matrix and scattering coefficients were acquired using a monitoring pulse sequenc...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.27038
更新日期:2018-08-01 00:00:00
abstract::We applied MRI to the in vivo detection of spontaneous colorectal tumors in a unique mouse model, the Fox Chase Cancer Center (FCCC) ApcMIN mouse. Unlike other Min (multiple intestinal neoplasia) strains, FCCC ApcMIN animals develop an appreciable number of tumors in the large intestine, which makes them an appropriat...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.20175
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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
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doi:10.1002/mrm.21390
更新日期:2007-10-01 00:00:00
abstract::Proton MRS (1 H MRS) provides noninvasive, quantitative metabolite profiles of tissue and has been shown to aid the clinical management of several brain diseases. Although most modern clinical MR scanners support MRS capabilities, routine use is largely restricted to specialized centers with good access to MR research...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章,评审
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更新日期:2019-08-01 00:00:00
abstract::Chemical shift imaging benefits from signal-to-noise ratio (SNR) and chemical shift dispersion increases at stronger main field such as 7 Tesla, but the associated shorter radiofrequency (RF) wavelengths encountered require B1+ mitigation over both the spatial field of view (FOV) and a specified spectral bandwidth. Th...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.21834
更新日期:2009-02-01 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
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doi:10.1002/mrm.1910390103
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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::Baseline distortion in NMR spectroscopy, caused by the "dead time" between signal excitation and detection, makes quantitative interpretation difficult and is aesthetically displeasing. Here the use of the CLEAN algorithm for deconvolving the effect of signal dead time to produce a distortionless baseline is discussed...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910130113
更新日期:1990-01-01 00:00:00
abstract:PURPOSE:To characterize the fundamental limits of MRI near metallic implants on RF excitation, frequency encoding, and chemical shift-encoding water-fat separation. METHODS:Multicomponent three-dimensional (3D) digital models of a total hip and a total knee replacement were used to construct material-specific suscepti...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25540
更新日期:2015-12-01 00:00:00
abstract::Focused ultrasound heating of ex vivo bovine kidney and liver was monitored using magnetic resonance imaging (MRI) to investigate the quantitative relationship between time-dependent temperature elevations and altered contrast in MR images due to thermal coagulation. Proton resonance frequency shift MR thermometry was...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199902)41:2<321::aid-mrm16
更新日期:1999-02-01 00:00:00
abstract::Accurate quantification of myocardial perfusion remains challenging due to saturation of the arterial input function at high contrast concentrations. A method for estimating the arterial input function directly from tissue curves in the myocardium that avoids these difficulties is presented. In this constrained altern...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22809
更新日期:2011-08-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910340328
更新日期:1995-09-01 00:00:00
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...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.1910300305
更新日期:1993-09-01 00:00:00
abstract::Orientational anisotropy of T2 and T1 relaxation times, diffusion, and magnetization transfer has been investigated for six different tissues: tendon, cartilage, kidney, muscle, white matter, and optic nerve. Relaxation anisotropy was observed for tendon and cartilage, and diffusional anisotropy was measured in kidney...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.1910320508
更新日期:1994-11-01 00:00:00
abstract::The purpose of the present study was to examine whether single human carcinoma cells labeled with iron oxide nanoparticles could be detected by magnetic resonance (MR) imaging on a clinical 3-T scanner using a surface coil only. WiDr human colon carcinoma cells were loaded with two kinds of iron oxide nanoparticles di...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.20455
更新日期:2005-05-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199904)41:4<657::aid-mrm3>
更新日期:1999-04-01 00:00:00
abstract:PURPOSE:The use of electromagnetic (EM) modeling is critical for specific absorption rate (SAR) characterization in parallel transmission MRI. Radiofrequency arrays that include decoupling networks can be difficult to characterize accurately in simulation. A practical method of simplifying modeling is to exclude the de...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25504
更新日期:2015-11-01 00:00:00
abstract::This paper describes a technique for characterizing the gradient subsystem of a magnetic resonance (MR) system. The technique uses a Fourier-transform analysis to directly measure the k-space trajectory produced by an arbitrary gradient waveform. In addition, the method can be easily extended to multiple dimensions an...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910390411
更新日期:1998-04-01 00:00:00
abstract::A novel method, called relaxo-oximetry, for rapid spatially resolved in vivo measurements of oxygen concentration using time-domain radiofrequency (RF) electron paramagnetic resonance (EPR) is described. Time-domain data from triaryl methyl (TAM)-based single-electron contrast agents were processed by systematic delet...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10133
更新日期:2002-05-01 00:00:00
abstract::MRI after a constant infusion (CI) of Gd-DTPA has been used to identify the extent of myocardial infarction (MI). However, Gd-DTPA-enhanced "viability" imaging is more commonly performed with a bolus (for "delayed-enhancement" (DE) imaging). This study sought to determine how image delay time and time postinfarction i...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20236
更新日期:2004-11-01 00:00:00
abstract:PURPOSE:To systematically evaluate the dependence of intravoxel-incoherent-motion (IVIM) parameters on the b-value threshold separating the perfusion and diffusion compartment, and to implement and test an algorithm for the standardized computation of this threshold. METHODS:Diffusion weighted images of the upper abdo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25506
更新日期:2015-11-01 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::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