Specific absorption rate benefits of including measured electric field interactions in parallel excitation pulse design.

abstract：:Magnetic resonance elastography (MRE) is a recently developed technique for determining the mechanical properties of biological tissue. In dynamic MRE, electromagnetic units (actuators) are widely used to generate shear waves in tissue. These actuators exploit the interaction between the static magnetic field B(0) and...

journal_title：Magnetic resonance in medicine

authors： Braun J,Braun K,Sack I

更新日期：2003-07-01 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

authors： Oregioni A,Parizel N,de Sousa PL,Grucker D

更新日期：2003-06-01 00:00:00

abstract：:Functional magnetic resonance imaging in real time is an emerging tool for the assessment of dynamic changes in brain activation. The short response latency (tens of seconds) renders the technique more sensitive to motion artifacts. Motion correction in real time requires computationally efficient algorithms which can...

journal_title：Magnetic resonance in medicine

authors： Mathiak K,Posse S

更新日期：2001-01-01 00:00:00

abstract：:Measurements of the volume magnetic susceptibility of solids using the classical Gouy balance approach are hampered by variations in apparent density of the packed powder. In this paper a quantitative NMR measurement of the volume magnetic susceptibility of powdered solids is described and the volume susceptibility of...

journal_title：Magnetic resonance in medicine

authors： Hopkins JA,Wehrli FW

更新日期：1997-04-01 00:00:00

abstract：:The purpose of this study is to examine the usefulness of histogram analysis combined with vessel size index (VSI) magnetic resonance imaging for the specific characterization of brain tumor microvasculature in a panel of six volume-matched glioma xenografts. Using a simple descriptive histogram analysis, significant ...

journal_title：Magnetic resonance in medicine

authors： Just N

更新日期：2011-03-01 00:00:00

abstract：:In this study, the precision and accuracy of a new method for measuring axial rotations of the lumbar vertebrae, which are thought to be increased in patients with degenerative spinal instability, were estimated. A standard image registration algorithm involving a user-selected center of rotation was adapted for this ...

journal_title：Magnetic resonance in medicine

authors： Rogers BP,Haughton VM,Arfanakis K,Meyerand ME

更新日期：2002-12-01 00:00:00

abstract：:A technique for noninvasively quantifying the concentration of sodium ((23) Na) ions was applied to the study of ischemic stroke. (23) Na-magnetic resonance imaging techniques have shown considerable potential for measuring subtle changes in ischemic tissue, although studies to date have suffered primarily from poor s...

journal_title：Magnetic resonance in medicine

authors： Wetterling F,Gallagher L,Macrae IM,Junge S,Fagan AJ

更新日期：2012-03-01 00:00:00

abstract：:A new 3D acquisition regimen that enables the collection of conventional, water-suppressed, and fat-suppressed images with no increase in scan times compared with currently implemented 3D sequences is presented. The method is based on conventional 3D steady state with interleaved selective excitation of the fat resona...

journal_title：Magnetic resonance in medicine

authors： Sun L,Aletras AH,Schmalbrock P,Skinner TE,Chakeres D,Irsik R,Robitaille PM

更新日期：1994-04-01 00:00:00

abstract：:The application of T1 rho an an alternative contrast parameter in high-field magnetic resonance histology (MRH) has been investigated. Spectroscopic measurements of T1 rho were performed on 5.75% agar and 1.0 mM MnCI2 phantoms at 9.4 T to validate the accuracy of the imaging measurements. Image studies were performed ...

journal_title：Magnetic resonance in medicine

authors： Engelhardt RT,Johnson GA

更新日期：1996-05-01 00:00:00

abstract：:In the recently proposed technique Sweep Imaging with Fourier Transform (SWIFT), frequency-modulated radiofrequency pulses are used in concert with simultaneous acquisition to facilitate MRI of samples with very short transverse relaxation time. In the present work, sweep MRI is reviewed from a reconstruction perspect...

journal_title：Magnetic resonance in medicine

authors： Weiger M,Hennel F,Pruessmann KP

更新日期：2010-12-01 00:00:00

abstract：PURPOSE:To present and validate a new method that formalizes a direct link between k-space and wavelet domains to apply separate undersampling and reconstruction for high- and low-spatial-frequency k-space data. THEORY AND METHODS:High- and low-spatial-frequency regions are defined in k-space based on the separation o...

journal_title：Magnetic resonance in medicine

authors： Sung K,Hargreaves BA

更新日期：2013-11-01 00:00:00

abstract：:An effective shield for the dc fringing fields produced by a large-bore, high field magnet intended for imaging and in vivo spectroscopy is presented. While limiting the extent of fringe fields, the shield has little effect on the homogeneity of the central field of the magnet. The effect of institutional safety polic...

journal_title：Magnetic resonance in medicine

authors： Ewing JR,Timms W,Williams JE,Welch KM

更新日期：1985-10-01 00:00:00

abstract：:Phase-contrast MRI can provide high-resolution angiographic velocity images, especially in conjunction with non-Cartesian k-space sampling. However, acquisitions can be sensitive to errors from artifacts from main magnetic field inhomogeneities and chemical shift from fat. Particularly in body imaging, fat content can...

journal_title：Magnetic resonance in medicine

authors： Johnson KM,Wieben O,Samsonov AA

更新日期：2010-06-01 00:00:00

abstract：:A method for calculating quantitative three-dimensional susceptibility maps from field measurements acquired using gradient echo imaging at high field is presented. This method is based on division of the three-dimensional Fourier transforms of high-pass-filtered field maps by a simple function that is the Fourier tra...

journal_title：Magnetic resonance in medicine

authors： Wharton S,Schäfer A,Bowtell R

更新日期：2010-05-01 00:00:00

abstract：:Two-dimensional T2-selective proton imaging of human head has been performed at 10 MHz employing Carr-Purcell-Gill-Meiboom pulse trains with echo separation of 6 and 12 msec. Using the information of 36 spin echoes and applying a recovery time of 2 sec the magnetization decay has been traced. The multi-exponential T2 ...

journal_title：Magnetic resonance in medicine

authors： Gersonde K,Felsberg L,Tolxdorff T,Ratzel D,Ströbel B

更新日期：1984-12-01 00:00:00

abstract：:A new NMR imaging technique, aiming at a reduction of the data acquisition time, is described in detail. The method is applicable in all multidimensional imaging situations where at least one spatial coordinate is resolved. Discussed at some length are the point-spread function, the required bandwidth of the NMR spect...

journal_title：Magnetic resonance in medicine

authors： van Uijen CM,den Boef JH,Verschuren FJ

更新日期：1985-06-01 00:00:00

abstract：PURPOSE:To enable highly accelerated distortion-free MRI near metal by separating on- and off-resonance to exploit the redundancy of slice-phase encoding for the dominant on-resonance component. METHODS:Multispectral MRI techniques resolve off-resonance distortions by a combination of limited excitation bins and addit...

journal_title：Magnetic resonance in medicine

authors： Levine E,Stevens K,Beaulieu C,Hargreaves B

更新日期：2018-03-01 00:00:00

abstract：PURPOSE:Vulnerable atherosclerotic plaques are structurally weak and prone to rupture, presumably due to local oxidative stress. Redox active iron is linked to oxidative stress and the aim of this study was to investigate the distribution of Fe(III) in carotid plaques and its relation to vulnerability for rupture. MET...

journal_title：Magnetic resonance in medicine

authors： Gustafsson H,Hallbeck M,Norell M,Lindgren M,Engström M,Rosén A,Zachrisson H

更新日期：2014-02-01 00:00:00

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 a...

journal_title：Magnetic resonance in medicine

authors： Wong EC,Cox RW,Song AW

更新日期：1995-08-01 00:00:00

abstract：:Whole-body NMR imaging antennas (probes) are strongly affected by the inevitable magnetic and controllable dielectric losses. Using a convenient parallelepiped model, the magnetic losses are evaluated. By introducing the "ideal power gain," the best possible antenna performance is delimited as a function of the freque...

journal_title：Magnetic resonance in medicine

authors： Sergiadis G

更新日期：1985-08-01 00:00:00

abstract：:A proton NMR relaxation and pulsed field gradient self-diffusion study of water in fibrin gels, plasma, and blood clots has been performed with special emphasis on the effect of the sol-gel and shrinkage transitions. Deuteron NMR in fibrin gels was also studied to supplement the proton data. It is shown that a measure...

journal_title：Magnetic resonance in medicine

authors： Blinc A,Lahajnar G,Blinc R,Zidansek A,Sepe A

更新日期：1990-04-01 00:00:00

abstract：PURPOSE:The purpose of this work was to develop and evaluate a robust water-fat separation method for T1-weighted symmetric two-point Dixon data. THEORY AND METHODS:A method for water-fat separation by phase unwrapping of the opposite-phase images by phase-sensitive reconstruction (PSR) is introduced. PSR consists of ...

journal_title：Magnetic resonance in medicine

authors： Romu T,Dahlström N,Leinhard OD,Borga M

更新日期：2017-09-01 00:00:00

abstract：:Surgical specimens from 22 patients with infiltrating ductal carcinoma of the breast were analyzed by high-resolution 1H NMR spectroscopy at 80 and 300 MHz. Results were compared with those obtained from 9 benign (proliferative dysplasia without atypia) breast samples. NMR spectra at 80 MHz showed well-resolved water ...

journal_title：Magnetic resonance in medicine

authors： Bradamante S,Barchiesi E,Pilotti S,Borasi G

更新日期：1988-12-01 00:00:00

abstract：PURPOSE:A purely experimental method for MRI-based transfer function (TF) determination is presented. A TF characterizes the potential for radiofrequency heating of a linear implant by relating the incident tangential electric field to a scattered electric field at its tip. We utilize the previously introduced transfer...

journal_title：Magnetic resonance in medicine

authors： Tokaya JP,Raaijmakers AJE,Luijten PR,Sbrizzi A,van den Berg CAT

更新日期：2020-03-01 00:00:00

abstract：PURPOSE:To develop an analytically based algorithm for rapid optimization of the local radiofrequency magnetic (B1+) field intensity for a given radiofrequency power through a transmit array. The analytical nature of the method will yield insight to optimization requirements and provides a valuable reference for numeri...

journal_title：Magnetic resonance in medicine

authors： Carluccio G,Collins CM,Erricolo D

更新日期：2014-01-01 00:00:00

abstract：PURPOSE:We describe a 2 × 6 channel sodium/proton array for knee MRI at 3T. Multielement coil arrays are desirable because of well-known signal-to-noise ratio advantages over volume and single-element coils. However, low tissue-coil coupling that is characteristic of coils operating at low frequency can make the potent...

journal_title：Magnetic resonance in medicine

authors： Brown R,Lakshmanan K,Madelin G,Alon L,Chang G,Sodickson DK,Regatte RR,Wiggins GC

更新日期：2016-10-01 00:00:00

abstract：:A general analytical framework is presented for the design of birdcage radiofrequency resonators on cylindrical formers having arbitrary cross-sectional shape. The primary objective of such shapes would be to improve the sensitivity of the NMR experiment to noncircular regions of the human anatomy while maintaining fi...

journal_title：Magnetic resonance in medicine

authors： De Zanche N,Yahya A,Vermeulen FE,Allen PS

更新日期：2005-01-01 00:00:00

abstract：:Regional values of fractional anisotropy (FA) and mean diffusivity (D(av)) of in vivo and excised rat spinal cords were measured using an iscosahedral encoding scheme that is based on 21 uniformly distributed and alternating gradient directions with an echo planar imaging (EPI) readout. Based on the water phantom stud...

journal_title：Magnetic resonance in medicine

authors： Madi S,Hasan KM,Narayana PA

更新日期：2005-01-01 00:00:00

abstract：:The preovulatory rat follicle reaches a diameter of 1 mm with no internal blood vessels. Nutrient supply to the enclosed oocyte depends solely on passive diffusion across the follicular wall and the follicular fluid. Spin-echo and stimulated-echo NMR microscopy experiments were applied here for studying modulations in...

journal_title：Magnetic resonance in medicine

authors： Tempel C,Schiffenbauer YS,Meir G,Neeman M

更新日期：1995-08-01 00:00:00

abstract：:A method for evaluating the sensitivity of MRI protocols to changes in an arbitrary number of tissue parameters over a broad range of parameter values is presented. This analysis is useful for choosing an optimal basis set of images for either a "survey" protocol or tissue segmentation algorithms. A survey protocol is...

journal_title：Magnetic resonance in medicine

authors： McVeigh ER,Henkelman RM,Bronskill MJ

更新日期：1990-02-01 00:00:00