Sources of functional apparent diffusion coefficient changes investigated by diffusion-weighted spin-echo fMRI.

abstract：PURPOSE:To develop a method based on fat-water transition region extraction (TREE) for robust fat-water separation and quantification in challenging scenarios, including low signal-to-noise ratio (SNR), fast changing B0 field, and disjointed anatomies. THEORY AND METHODS:In TREE method, the phasor solutions of each pi...

journal_title：Magnetic resonance in medicine

authors： Peng H,Zou C,Cheng C,Tie C,Qiao Y,Wan Q,Lv J,He Q,Liang D,Liu X,Liu W,Zheng H

更新日期：2019-07-01 00:00:00

abstract：:In a systematic study on the interdependence of linewidth, signal-to-noise ratio (SNR), and spatial resolution in 3D proton spectroscopic imaging ((1)H-SI) at 3 T, we demonstrate reduced linewidths with increased spatial resolution due to reduced magnetic inhomogeneity within the brain. High-precision quantitative dat...

journal_title：Magnetic resonance in medicine

authors： Gruber S,Mlynárik V,Moser E

更新日期：2003-02-01 00:00:00

abstract：:Experimental procedures for obtaining localized 31P NMR spectra of humans by means of the ISIS sequence are discussed in detail. The technique is optimized for use with volume coils and with surface coils in order to measure localized 31P NMR spectra of different tissues and organs. Selective frequency-modulated (FM) ...

journal_title：Magnetic resonance in medicine

authors： Luyten PR,Groen JP,Vermeulen JW,den Hollander JA

更新日期：1989-07-01 00:00:00

abstract：PURPOSE:To measure the apparent diffusion coefficients (ADC) of five main metabolites in the human brain at 3T with PRESS and STEAM, avoiding measurement biases because of cross-terms. Cross-terms arise from interactions between slice-selection and spoiler gradients in the localized spectroscopy sequence and the diffus...

journal_title：Magnetic resonance in medicine

authors： Deelchand DK,Auerbach EJ,Marjańska M

更新日期：2018-06-01 00:00:00

abstract：:Accurate and reproducible MRI R2 * relaxometry for tissue iron quantification is important in managing transfusion-dependent patients. MRI data are often acquired using array coils and reconstructed by the root-sum-square algorithm, and as such, measured signals follow the noncentral chi distribution. In this study, t...

journal_title：Magnetic resonance in medicine

authors： Feng Y,He T,Gatehouse PD,Li X,Harith Alam M,Pennell DJ,Chen W,Firmin DN

更新日期：2013-12-01 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

authors： Kim B,Boes JL,Bland PH,Chenevert TL,Meyer CR

更新日期：1999-05-01 00:00:00

abstract：:To quantify the extraction fraction, E, for gadopentetate across tumor capillaries, R3230 adenocarcinomas were implanted in the mammary fat pads of seven rats. The value of E was determined by using a two-compartment tissue model in which the endothelial transfer coefficient, K(PS) (ml x min(-1) x cc(-1) of tissue), w...

journal_title：Magnetic resonance in medicine

authors： Daldrup HE,Shames DM,Husseini W,Wendland MF,Okuhata Y,Brasch RC

更新日期：1998-10-01 00:00:00

abstract：:Successful radiofrequency (RF) thermal ablation was performed on VX2 tumors implanted in 23 rabbit livers under magnetic resonance (MR) guidance using a C-arm-shaped low-field 0.2 T system. RF application and immediate postprocedure MRI of all animals was performed [T2-weighted, turbo short tau inversion recovery (STI...

journal_title：Magnetic resonance in medicine

authors： Merkle EM,Boll DT,Boaz T,Duerk JL,Chung YC,Jacobs GH,Varnes ME,Lewin JS

更新日期：1999-07-01 00:00:00

abstract：PURPOSE:To investigate and compare several quantification methods of myocardial perfusion measurements, paying special attention to the relation between the techniques and the required measurement duration. METHODS:Seven patients underwent contrast-enhanced rest and stress cardiac perfusion measurements at 3T. Three s...

journal_title：Magnetic resonance in medicine

authors： Schwab F,Ingrisch M,Marcus R,Bamberg F,Hildebrandt K,Adrion C,Gliemi C,Nikolaou K,Reiser M,Theisen D

更新日期：2015-03-01 00:00:00

abstract：PURPOSE:To study the utility of fractional calculus in modeling gradient-recalled echo MRI signal decay in the normal human brain. METHODS:We solved analytically the extended time-fractional Bloch equations resulting in five model parameters, namely, the amplitude, relaxation rate, order of the time-fractional derivat...

journal_title：Magnetic resonance in medicine

authors： Qin S,Liu F,Turner IW,Yu Q,Yang Q,Vegh V

更新日期：2017-04-01 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

authors： Lyon RC,Tschudin RG,Daly PF,Cohen JS

更新日期：1988-01-01 00:00:00

abstract：:A method for collecting MRI data on a set of rotated trajectories that begin at the center of k-space is outlined. It is theoretically slightly faster, slightly less susceptible to off-resonance and motion-induced phase, and produces images with slightly better signal-to-noise ratio than methods using Archimedean spir...

journal_title：Magnetic resonance in medicine

authors： Pipe JG

更新日期：1999-10-01 00:00:00

abstract：:A regularized algorithm is presented for localized in vivo shimming. The technique uses first- (X,Y,Z), second- (Z(2), ZX, ZY, X(2)-Y(2), XY), and third-order (Z(3)) shim coils, and is robust when applied to arbitrarily-shaped, as well as off-center, regions of interest (ROIs). A single-shot spiral pulse sequence is u...

journal_title：Magnetic resonance in medicine

authors： Kim DH,Adalsteinsson E,Glover GH,Spielman DM

更新日期：2002-10-01 00:00:00

abstract：:It is shown that in vivo measurement of bile water apparent diffusion coefficient (ADC) by diffusion-weighted echo-planar imaging (EPI) in hamster gallbladder is possible providing motion artifact-free ADC values. These ADC values are used to estimate bile viscosity variation induced by normal diets, cholesterol galls...

journal_title：Magnetic resonance in medicine

authors： Tiffon B,Parquet M,Dubrac S,Lutton C,Volk A

更新日期：2000-06-01 00:00:00

abstract：:Localized 7Li MR point-resolved spectroscopy (PRESS) was developed as a technique to measure lithium (Li) concentration in rat brain in vivo. Localized 7Li spectra could be obtained at 4.7 T in a 0.7-ml voxel in rat brain over the entire therapeutic range of serum Li for humans. Localized 7Li spin-lattice (T1) and spi...

journal_title：Magnetic resonance in medicine

authors： Komoroski RA,Pearce JM

更新日期：2004-07-01 00:00:00

abstract：PURPOSE:A new method, called Transmit and Receive Patterns from Low-Tip-angle gradient-Echo Images (TRIPLET), is described which simultaneously maps the B1+ and B1- fields of a transmit/receive radiofrequency coil array. The input data are low-tip-angle gradient-echo images, which can be acquired in a relatively short ...

journal_title：Magnetic resonance in medicine

authors： Sbrizzi A,Raaijmakers AJ,Hoogduin H,Lagendijk JJ,Luijten PR,van den Berg CA

更新日期：2014-07-01 00:00:00

abstract：:In this high resolution magnetic resonance spectroscopic study of experimental allergic encephalomyelitis (EAE) and Semliki Forest virus (SFV) infection of the Biozzi AB/H mouse, marked increases in the initially low levels of N-trimethyl compounds in the spinal cord were observed during probable demyelinating episode...

journal_title：Magnetic resonance in medicine

authors： Preece NE,Amor S,Baker D,Gadian DG,O'Neill JK,Urenjak J

更新日期：1994-12-01 00:00:00

abstract：PURPOSE:To design low peak and integrated power simultaneous multislice excitation radiofrequency pulses with transmit field inhomogeneity compensation in high field MRI. THEORY AND METHODS:The "interleaved greedy and local optimization" algorithm for small-tip-angle spokes pulses is extended to design multiband (MB) ...

journal_title：Magnetic resonance in medicine

authors： Sharma A,Bammer R,Stenger VA,Grissom WA

更新日期：2015-09-01 00:00:00

abstract：:In the pulsed arterial spin labeling (ASL) techniques EPISTAR, PICORE, and FAIR, subtraction of two images in which inflowing blood is first tagged and then not tagged yields a qualitative map of perfusion. An important reason this map is not quantitative is that there is a spatially varying delay in the transit of bl...

journal_title：Magnetic resonance in medicine

authors： Wong EC,Buxton RB,Frank LR

更新日期：1998-05-01 00:00:00

abstract：:A robust postprocessing method to detect regions of magnetic field change is presented. High resolution gradient echo data is acquired to create a complex baseline image. From this image, two low resolution images are obtained by applying a low pass filter on the magnitude image and the complex image, respectively. Su...

journal_title：Magnetic resonance in medicine

authors： Lai S,Reichenbach JR,Haacke EM

更新日期：1996-11-01 00:00:00

abstract：:We propose a new magnetic resonance imaging (MRI) technique that is sensitive to myocardial tissue perfusion that obviates the use of an extrinsic contrast agent. Significant advantages of such a technique are that it avoids accumulation of contrast agent when repeated studies are performed on the same subject and tha...

journal_title：Magnetic resonance in medicine

authors： Prasad PV,Burstein D,Edelman RR

更新日期：1993-08-01 00:00:00

abstract：:Compressed sensing has been of great interest to speed up the acquisition of MR images. The k-t group sparse (k-t GS) method has recently been introduced for dynamic MR images to exploit not just the sparsity, as in compressed sensing, but also the spatial group structure in the sparse representation. k-t GS achieves ...

journal_title：Magnetic resonance in medicine

authors： Prieto C,Usman M,Wild JM,Kozerke S,Batchelor PG,Schaeffter T

更新日期：2013-04-01 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：PURPOSE:As the premiere modality for brain imaging, MRI could find wider applicability if lightweight, portable systems were available for siting in unconventional locations such as intensive care units, physician offices, surgical suites, ambulances, emergency rooms, sports facilities, or rural healthcare sites. METH...

journal_title：Magnetic resonance in medicine

authors： Cooley CZ,Stockmann JP,Armstrong BD,Sarracanie M,Lev MH,Rosen MS,Wald LL

更新日期：2015-02-01 00:00:00

abstract：:Echo-planar spectroscopic imaging (EPSI) can be used for fast spectroscopic imaging of water and fat resonances at high resolution to improve structural and functional imaging. Because of the use of oscillating gradients during the free induction decay (FID), spectra obtained with EPSI are often degraded by Nyquist gh...

journal_title：Magnetic resonance in medicine

authors： Du W,Du YP,Fan X,Zamora MA,Karczmar GS

更新日期：2003-06-01 00:00:00

abstract：PURPOSE:Amide-proton transfer (APT) and amine-water proton exchange (APEX) MRI can be viable to map pH-decreasing ischemic regions. However, their exact contributions are unclear. METHODS:We measured APEX- and APT-weighted magnetization transfer ratio asymmetry (denoted as APEXw and APTw), apparent diffusion coefficie...

journal_title：Magnetic resonance in medicine

authors： Zong X,Wang P,Kim SG,Jin T

更新日期：2014-01-01 00:00:00

abstract：:Spin-echo images of 10 myocardial infarcts in nine mini-pigs were obtained at 30 h, 3 days, and approximately 10 days postinfarction. Infarcts were not detected at all at 30 h in five out of five cases examined. At 3 days postembolization (six cases) one infarct was certainly detected, whilst at 10 days (nine cases) a...

journal_title：Magnetic resonance in medicine

authors： Checkley D,Loveday BE,Waterton JC,Zhu XP,Isherwood I

更新日期：1987-09-01 00:00:00

abstract：:Techniques are described for the (31)P NMR analysis of glycerophospholipid (PL) headgroup and molecular species in brain. The (31)P NMR spectrum of PLs from human temporal cortex, solubilized in aqueous Na cholate, typically showed 3 major resonances, assigned to phosphatidylcholine (PC) molecular species containing 0...

journal_title：Magnetic resonance in medicine

authors： Pearce JM,Komoroski RA

更新日期：2000-08-01 00:00:00

abstract：PURPOSE:To develop a method that fits a multipool model to z-spectra acquired from non-steady state sequences, taking into account the effects of variations in T1 or B1 amplitude and the results estimating the parameters for a four-pool model to describe the z-spectrum from the healthy brain. METHODS:We compared measu...

journal_title：Magnetic resonance in medicine

authors： Geades N,Hunt BAE,Shah SM,Peters A,Mougin OE,Gowland PA

更新日期：2017-08-01 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

authors： Beqiri A,Hand JW,Hajnal JV,Malik SJ

更新日期：2015-11-01 00:00:00