Impact of signal-to-noise on functional MRI.

abstract：PURPOSE:The aim of the study was to investigate whether incorrectly compensated eddy currents are the source of persistent X-nuclear spectroscopy and imaging artifacts, as well as methods to correct this. METHODS:Pulse-acquire spectra were collected for 1 H and X-nuclei (23 Na or 31 P) using the minimum TR permitted o...

journal_title：Magnetic resonance in medicine

authors： McLean MA,Hinks RS,Kaggie JD,Woitek R,Riemer F,Graves MJ,McIntyre DJO,Gallagher FA,Schulte RF

更新日期：2020-12-04 00:00:00

abstract：PURPOSE:It has been shown, theoretically and in vivo, that using the Stejskal-Tanner pulsed-gradient, or linear tensor encoding (LTE), and in tissue exhibiting a "stick-like" diffusion geometry, the direction-averaged diffusion-weighted MRI signal at high b-values ( ...

journal_title：Magnetic resonance in medicine

authors： Afzali M,Aja-Fernández S,Jones DK

更新日期：2020-09-01 00:00:00

abstract：:Chemical shift-based multipoint water-fat separation methods have been applied in balanced steady-state free precession (bSSFP) sequences because of the high signal-to-noise-ratio (SNR) attainable. In this approach the echo formation is approximated to occur concurrently for both water and fat at an echo time (TE) equ...

journal_title：Magnetic resonance in medicine

authors： Kim H,Pinus AB,Wang J,Murphy PS,Constable RT

更新日期：2007-08-01 00:00:00

abstract：PURPOSE:Magnetic susceptibility is a physical property of matter that varies depending on chemical composition and abundance of different molecular species. Interest is growing in mapping of magnetic susceptibility in the human brain using magnetic resonance imaging techniques, but the influences affecting the mapped v...

journal_title：Magnetic resonance in medicine

authors： Sood S,Urriola J,Reutens D,O'Brien K,Bollmann S,Barth M,Vegh V

更新日期：2017-05-01 00:00:00

abstract：:The MMQ cell line is a unique prolactin-secreting rat pituitary cell line. MMQ cells entrapped in agarose gel threads are metabolically active, as determined by the uptake and phosphorylation of creatine and the maintenance of high energy phosphates for over 15 h. Forskolin activates the catalytic subunit of adenylyl ...

journal_title：Magnetic resonance in medicine

authors： Goger MJ,Login IS,Fernandez EJ,Grisham CM

更新日期：1994-11-01 00:00:00

abstract：:Dextran-magnetite, a superparamagnetic compound, is a powerful relaxation reagent for sodium. Administered intravenously, it is confined mainly to the vasculature and eliminates the signal from plasma sodium, a significant component of the tissue sodium signal. Applications of dextran-magnetite for in vivo sodium imag...

journal_title：Magnetic resonance in medicine

authors： Summers RM,Joseph PM,Renshaw PF,Kundel HL

更新日期：1988-12-01 00:00:00

abstract：PURPOSE:Previous work has evaluated the quality of different analytic methods for extracting relaxation times from magnitude imaging data exhibiting Rician noise. However, biexponential analysis of relaxation in tissue, including cartilage, and materials is of increasing interest. We, therefore, analyzed biexponential ...

journal_title：Magnetic resonance in medicine

authors： Bouhrara M,Reiter DA,Celik H,Bonny JM,Lukas V,Fishbein KW,Spencer RG

更新日期：2015-01-01 00:00:00

abstract：PURPOSE:To enable fast and flexible high-resolution four-dimensional (4D) MRI of periodic thoracic/abdominal motion for motion visualization or motion-corrected imaging. METHODS:We proposed a Cartesian three-dimensional k-space sampling scheme that acquires a random combination of k-space lines in the ky/kz plane. A p...

journal_title：Magnetic resonance in medicine

authors： Küstner T,Würslin C,Schwartz M,Martirosian P,Gatidis S,Brendle C,Seith F,Schick F,Schwenzer NF,Yang B,Schmidt H

更新日期：2017-08-01 00:00:00

abstract：:In order to determine if an increase in myocardial oxygen consumption is accompanied by changes in high energy phosphates in normal subjects and patients with dilated cardiomyopathy, phosphorus-31 spectra were acquired under resting conditions and during dobutamine infusion. In seven normal subjects, dobutamine raised...

journal_title：Magnetic resonance in medicine

authors： Schaefer S,Schwartz GG,Steinman SK,Meyerhoff DJ,Massie BM,Weiner MW

更新日期：1992-06-01 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:We report a series of techniques to reliably eliminate artifacts in interleaved echo-planar imaging (EPI) based diffusion-weighted imaging (DWI). METHODS:First, we integrate the previously reported multiplexed sensitivity encoding (MUSE) algorithm with a new adaptive Homodyne partial-Fourier reconstruction alg...

journal_title：Magnetic resonance in medicine

authors： Chang HC,Guhaniyogi S,Chen NK

更新日期：2015-05-01 00:00:00

abstract：:Two different types of (co-registered) images of the same slice of tissue will generally have different spatial resolutions. The judicious pixel-by-pixel combination of their data can be accomplished to yield a single image exhibiting properties of both. Here, axial (18)FDG PET and (1)H(2)O MR images of the human brai...

journal_title：Magnetic resonance in medicine

authors： Sammi MK,Felder CA,Fowler JS,Lee JH,Levy AV,Li X,Logan J,Pályka I,Rooney WD,Volkow ND,Wang GJ,Springer CS Jr

更新日期：1999-08-01 00:00:00

abstract：PURPOSE:To demonstrate the feasibility of imaging a bolus of co-polarized [1-13 C]pyruvate and 13 C-urea to simultaneously assess both metabolism and perfusion in the rodent heart. METHODS:Copolarized [1-13 C]pyruvate and 13 C-urea was imaged using a multi-echo, flow-sensitized spiral pulse sequence. Healthy rats were...

journal_title：Magnetic resonance in medicine

authors： Lau AZ,Miller JJ,Robson MD,Tyler DJ

更新日期：2017-01-01 00:00:00

abstract：:Manganese is a useful contrast agent for MRI of animals. Previously, it has been shown that systemic doses of MnCl(2) provide unique contrast in the rodent brain, enabling visualization of neuroarchitecture. The present work investigates the dose and temporal dependence of brain enhancement after i.v. administration o...

journal_title：Magnetic resonance in medicine

authors： Lee JH,Silva AC,Merkle H,Koretsky AP

更新日期：2005-03-01 00:00:00

abstract：PURPOSE:MUSSELS is a one-step iterative reconstruction method for multishot diffusion weighted (msDW) imaging. The current work presents an efficient implementation, termed IRLS MUSSELS, that enables faster reconstruction to enhance its utility for high-resolution diffusion MRI studies. METHODS:The recently proposed M...

journal_title：Magnetic resonance in medicine

authors： Mani M,Aggarwal HK,Magnotta V,Jacob M

更新日期：2020-06-01 00:00:00

abstract：:Using a material that already is in widespread use in humans, India ink, the first EPR measurements in a human have been made, using the India ink in a pre-existing tattoo. The EPR spectra of India ink are very sensitive to the partial pressure of oxygen (pO2), thereby making it feasible to use this approach to measur...

journal_title：Magnetic resonance in medicine

authors： Swartz HM,Liu KJ,Goda F,Walczak T

更新日期：1994-02-01 00:00:00

abstract：PURPOSE:To examine the detection sensitivity for the rapidly exchanging hydroxyl protons of D-glucose using the recently developed on-resonance variable delay multi-pulse (onVDMP) chemical exchange saturation transfer (CEST) technique. METHODS:The onVDMP method was applied for the detection of water signal changes upo...

journal_title：Magnetic resonance in medicine

authors： Xu X,Xu J,Chan KWY,Liu J,Liu H,Li Y,Chen L,Liu G,van Zijl PCM

更新日期：2019-01-01 00:00:00

abstract：PURPOSE:A multi-turn transmit surface coil design was presented to improve B1 efficiency when used with current source amplification. METHODS:Three different coil designs driven by an on-coil current-mode class-D amplifier with current envelope feedback were tested on the benchtop and through imaging in a 1.5 T scanne...

journal_title：Magnetic resonance in medicine

authors： Gudino N,Griswold MA

更新日期：2013-04-01 00:00:00

abstract：:Two NMR experiments are described that use ac field gradients to measure flow velocities. Both experiments perform no spacial localization; instead, fluid velocity is converted to a resonance frequency shift. Thus, by Fourier transformation of a single FID or echo train the distribution of velocities is available. The...

journal_title：Magnetic resonance in medicine

authors： Walton JH,Conradi MS

更新日期：1987-03-01 00:00:00

abstract：PURPOSE:To investigate the feasibility of estimating calibration constants (K and T2o ) in vivo for converting whole-blood T2 to blood hemoglobin oxygen saturation (HbO2 ) according to the Luz-Meiboom model, 1/T2=1/T2o+K(1-HbO2)2, where K and T2o are relaxivity and transverse relaxation time of fully saturated blood, r...

journal_title：Magnetic resonance in medicine

authors： Langham MC,Rodríguez-Soto AE,Schwartz N,Wehrli FW

更新日期：2018-04-01 00:00:00

abstract：:The intra-individual and inter-individual variations of the global N-acetylaspartate (NAA) concentration were measured in a cohort of five 42+/-5 year-old normal females. The total NAA signal from the whole head was obtained with non-localized non-echo proton spectroscopy (1H-MRS) and converted into absolute mole amou...

journal_title：Magnetic resonance in medicine

authors： Gonen O,Viswanathan AK,Catalaa I,Babb J,Udupa J,Grossman RI

更新日期：1998-11-01 00:00:00

abstract：:The acquisition of complete three-dimensional (3D), segmented gradient-echo data sets to visualize the coronary arteries can be both time consuming and sensitive to motion, even with use of multiple breath-holding or respiratory gating. An alternate hybrid approach is demonstrated here, in which real-time interactive ...

journal_title：Magnetic resonance in medicine

authors： Hardy CJ,Darrow RD,Pauly JM,Kerr AB,Dumoulin CL,Hu BS,Martin KM

更新日期：1998-07-01 00:00:00

abstract：:At TE values of 136 ms, it has recently been shown that the lactate methyl signal, when obtained with a stimulated-echo (STE) sequence, is modulated at the zero-quantum (ZQ) frequency when TM is varied. Here we describe an additional modulation of the ZQ lactate signal, due to spin-spin coupling, that results in a 10-...

journal_title：Magnetic resonance in medicine

authors： Sotak CH,Alger JR

更新日期：1991-02-01 00:00:00

abstract：:In echo-planar-based diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI), the evaluation of diffusion parameters such as apparent diffusion coefficients and anisotropy indices is affected by image distortions that arise from residual eddy currents produced by the diffusion-sensitizing gradients. Correc...

journal_title：Magnetic resonance in medicine

authors： Bodammer N,Kaufmann J,Kanowski M,Tempelmann C

更新日期：2004-01-01 00:00:00

abstract：:Magnetic resonance (MR) imaging and relaxation time measurements of bioresorbable implants made of polylactic acid (PLA), as well as the surrounding tissues, were carried out over a period of 6 months to monitor the implant state and the body's responses, and to determine how these processes are reflected in MR data. ...

journal_title：Magnetic resonance in medicine

authors： Stroman PW,Dorvil JC,Marois Y,Poddevin N,Guidoin R

更新日期：1999-07-01 00:00:00

abstract：:When using tracer kinetic modeling to analyze dynamic contrast-enhanced MRI (DCE-MRI) it is necessary to identify an appropriate arterial input function (AIF). The measured AIF is often poorly sampled in both clinical and preclinical MR systems due to the initial rapid increase in contrast agent concentration and the ...

journal_title：Magnetic resonance in medicine

authors： McGrath DM,Bradley DP,Tessier JL,Lacey T,Taylor CJ,Parker GJ

更新日期：2009-05-01 00:00:00

abstract：PURPOSE:Delta relaxation enhanced magnetic resonance (dreMR) imaging requires an auxiliary B0 electromagnet capable of shifting the main magnetic field within a clinical 1.5 Tesla (T) MR system. In this work, the main causes of interaction between an actively shielded, insertable resistive B0 electromagnet and a 1.5T s...

journal_title：Magnetic resonance in medicine

authors： Harris CT,Handler WB,Araya Y,Martínez-Santiesteban F,Alford JK,Dalrymple B,Van Sas F,Chronik BA,Scholl TJ

更新日期：2014-10-01 00:00:00

abstract：PURPOSE:At high field, T2 -weighted (T2 w) imaging is limited by transmit field inhomogeneity and increased radiofrequency power deposition. In this work, we introduce SAMPA (Slice-selective Adiabatic Magnetization T2 PrepAration) and demonstrate its use for efficient brain T2 w imaging at 7 Tesla (T). METHODS:SAMPA w...

journal_title：Magnetic resonance in medicine

authors： Dyvorne H,Balchandani P

更新日期：2016-12-01 00:00:00

abstract：PURPOSE:To introduce a multiplatform, Python language-based, development environment called graphical programming interface for prototyping MRI techniques. METHODS:The interface allows developers to interact with their scientific algorithm prototypes visually in an event-driven environment making tasks such as paramet...

journal_title：Magnetic resonance in medicine

authors： Zwart NR,Pipe JG

更新日期：2015-11-01 00:00:00

abstract：PURPOSE:To develop and evaluate a technique for accelerating phase contrast MRI (PC-MRI) acquisitions without significant compromise in flow quantification accuracy. METHODS:PC-MRI is commonly acquired using interleaved flow-compensated (FC) and flow-encoded (FE) echoes. We hypothesized that FC data, which represent b...

journal_title：Magnetic resonance in medicine

authors： Wang D,Shao J,Rapacchi S,Middione MJ,Ennis DB,Hu P

更新日期：2015-02-01 00:00:00