Human whole-blood (1)H2O longitudinal relaxation with normal and high-relaxivity contrast reagents: influence of trans-cell-membrane water exchange.

abstract：PURPOSE:Acquisition of high-resolution imaging data using multiple excitations without the sensitivity to fluctuations of the transverse magnetization phase, which is a major problem of multi-shot MRI. THEORY AND METHODS:The concept of superresolution MRI based on microscopic tagging is analyzed using an analogy with ...

journal_title：Magnetic resonance in medicine

authors： Hennel F,Tian R,Engel M,Pruessmann KP

更新日期：2018-12-01 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

authors： Marshall H,Parra-Robles J,Deppe MH,Lipson DA,Lawson R,Wild JM

更新日期：2014-03-01 00:00:00

abstract：:This report describes a noninvasive 1H-NMR method for measuring absolute temperatures (+/- 0.2 degrees C) in biological samples and, in particular, in cell culture perfusion systems, utilizing the linear temperature dependence of the water chemical shift relative to the temperature-independent shift of one of the comp...

journal_title：Magnetic resonance in medicine

authors： Lutz NW,Kuesel AC,Hull WE

更新日期：1993-01-01 00:00:00

abstract：:For clinical 31P MR spectroscopic imaging (MRSI) studies, where signal averaging is necessary, some improvement of sensitivity and spatial response function may be achieved by acquiring data over a spherical k-space volume and varying the number of averages acquired in proportion to the desired spatial filter. Eight d...

journal_title：Magnetic resonance in medicine

authors： Hugg JW,Maudsley AA,Weiner MW,Matson GB

更新日期：1996-09-01 00:00:00

abstract：PURPOSE:Diffusion magnetic resonance imaging (MRI) microstructure imaging provides a unique noninvasive probe into tissue microstructure. The technique relies on biophysically motivated mathematical models, relating microscopic tissue features to the magnetic resonance (MR) signal. This work aims to determine which com...

journal_title：Magnetic resonance in medicine

authors： Ferizi U,Schneider T,Panagiotaki E,Nedjati-Gilani G,Zhang H,Wheeler-Kingshott CA,Alexander DC

更新日期：2014-12-01 00:00:00

abstract：PURPOSE:Balanced steady state free precession (bSSFP) imaging suffers from off-resonance artifacts such as signal modulation and banding. Solutions for removal of bSSFP off-resonance dependence are described and compared, and an optimal solution is proposed. THEORY AND METHODS:An Algebraic Solution (AS) that complemen...

journal_title：Magnetic resonance in medicine

authors： Hoff MN,Andre JB,Xiang QS

更新日期：2017-02-01 00:00:00

abstract：:Prepolarized MRI uses pulsed magnetic fields to produce MR images by polarizing the sample at one field strength (approximately 0.5 T) before imaging at a much lower field (approximately 50 mT). Contrast reflecting the T(1) of the sample at an intermediate field strength is achieved by polarizing the sample and then a...

journal_title：Magnetic resonance in medicine

authors： Ungersma SE,Matter NI,Hardy JW,Venook RD,Macovski A,Conolly SM,Scott GC

更新日期：2006-06-01 00:00:00

abstract：:A methodology is presented for estimating T(1) using a two-point technique with a standard multislice gradient echo sequence. The method explicitly corrects for the shape of the RF pulse and for spatial variations in transmitted RF field intensity. Including these factors in the calculation of T(1) gives a substantial...

journal_title：Magnetic resonance in medicine

authors： Parker GJ,Barker GJ,Tofts PS

更新日期：2001-05-01 00:00:00

abstract：PURPOSE:The apparent propagator anisotropy (APA) is a new diffusion MRI metric that, while drawing on the benefits of the ensemble averaged propagator anisotropy (PA) compared to the fractional anisotropy (FA), can be estimated from single-shell data. THEORY AND METHODS:Computation of the full PA requires acquisition ...

journal_title：Magnetic resonance in medicine

authors： Aja-Fernández S,Tristán-Vega A,Jones DK

更新日期：2020-12-13 00:00:00

abstract：:The concept of temporal echo multiplexing is defined and used to develop rapid biphasic spin-echo sequences for imaging the heart. Three imaging sequences, based on four-echo and two-echo multiplexing and rapid single echo (i.e., conventional spin-echo imaging), are compared. Preliminary results indicate that two-echo...

journal_title：Magnetic resonance in medicine

authors： Parker DL,Caputo GR,Frederick PR

更新日期：1989-07-01 00:00:00

abstract：:The hypothesis was tested that the intravoxel distribution of water diffusion rates, as measured with a stretched-exponential model of diffusion-weighted imaging (DWI), is a marker of brain tumor invasion. Eight rats underwent intracerebral inoculation of C6 glioma cells. In three rats, cells were labeled with a fluor...

journal_title：Magnetic resonance in medicine

authors： Bennett KM,Hyde JS,Rand SD,Bennett R,Krouwer HG,Rebro KJ,Schmainda KM

更新日期：2004-11-01 00:00:00

abstract：:Diffusion tensor imaging (DTI) is a new imaging modality that can provide unique information on brain white matter anatomy. Measurements of water diffusion constant along multiple axes are fitted to a tensor model, from which the diffusion anisotropy and dominant fiber orientation can be estimated. Even though the ten...

journal_title：Magnetic resonance in medicine

authors： Zhang J,van Zijl PC,Mori S

更新日期：2006-02-01 00:00:00

abstract：:The study of brain function using MRI relies on acquisition techniques that are sensitive to different aspects of the hemodynamic response contiguous to areas of neuronal activity. For this purpose different contrasts such as arterial spin labeling (ASL) and blood oxygenation level dependent (BOLD) functional MRI tech...

journal_title：Magnetic resonance in medicine

authors： Woolrich MW,Chiarelli P,Gallichan D,Perthen J,Liu TT

更新日期：2006-10-01 00:00:00

abstract：:Minimally invasive cardiac surgery requires arresting and emptying of the heart, which compromises visualization of the surgical field. In this feasibility study a novel surgical procedure is demonstrated in which real-time MRI is used to guide the placement of a prosthetic aortic valve in the beating heart via direct...

journal_title：Magnetic resonance in medicine

authors： McVeigh ER,Guttman MA,Lederman RJ,Li M,Kocaturk O,Hunt T,Kozlov S,Horvath KA

更新日期：2006-11-01 00:00:00

abstract：PURPOSE:Sensitivity encoding (SENSE) reconstruction of multiband echo planar imaging (EPI) may cause artifacts when simultaneously excited slices require different phase correction to remove the EPI-specific ghost shifted by half of the matrix size (N). We propose a simplified solution of this problem that combines SEN...

journal_title：Magnetic resonance in medicine

authors： Hennel F,Buehrer M,von Deuster C,Seuven A,Pruessmann KP

更新日期：2016-09-01 00:00:00

abstract：PURPOSE:Transverse relaxation time (T2 ) mapping with MRI has a plethora of clinical and research applications. Current T2 mapping techniques are based primarily on spin-echo (SE) relaxometry strategies that rely on the signal magnitude, and often suffer from lengthy acquisition times. In this work, we propose a phase-...

journal_title：Magnetic resonance in medicine

authors： Wang X,Hernando D,Reeder SB

更新日期：2020-08-01 00:00:00

abstract：:Three-dimensional spatial-spectral radiofrequency pulses using a stack-of-spirals trajectory can achieve two-dimensional spatial localization and one-dimensional spectral selection simultaneously. These pulses are useful, for example, in reduced field-of-view applications that also require frequency specificity such a...

journal_title：Magnetic resonance in medicine

authors： Deng W,Stenger VA

更新日期：2010-03-01 00:00:00

abstract：:Intermolecular double quantum coherences (iDQCs), signals that result from simultaneous transitions of two or more separated spins, are known to produce images that are highly sensitive to subvoxel structure, particularly local anisotropy. Here we demonstrate how iDQCs signal can be used to efficiently detect the anis...

journal_title：Magnetic resonance in medicine

authors： Branca RT,Chen YM,Mouraviev V,Galiana G,Jenista ER,Kumar C,Leuschner C,Warren WS

更新日期：2009-04-01 00:00:00

abstract：:A method for volume selective proton spectroscopy is presented based on a multiecho sequence with short refocusing interval tcp. It is demonstrated, that by appropriate choice of tcp on the order of 4-6 ms, signals from overlapping multiplets like the glutamine and glutamate (Glu/Gln) resonances in spectra of the huma...

journal_title：Magnetic resonance in medicine

authors： Hennig J,Thiel T,Speck O

更新日期：1997-06-01 00:00:00

abstract：:The cytosol of intact human red blood cells was loaded with 28.1 +/- 3.4 mM of dysprosium DTPA-BMA using a hypoosmotic technique. When loaded cells were diluted with saline and control cells to give an average dysprosium concentration of 3.3 +/- 0.5 mM, the transverse relaxation rate constants R(*)(2) and R(2) increas...

journal_title：Magnetic resonance in medicine

authors： Johnson KM,Tao JZ,Kennan RP,Gore JC

更新日期：2001-05-01 00:00:00

abstract：:A new fully automatic algorithm for the segmentation of the brain and total intracranial cerebrospinal fluid (CSF) from T(1)-weighted volume MRI scans of the head, called Exbrain v.2, is described. The algorithm was developed in the context of serial intracranial volumetry. A brain mask obtained using a previous versi...

journal_title：Magnetic resonance in medicine

authors： Lemieux L,Hammers A,Mackinnon T,Liu RS

更新日期：2003-05-01 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

authors： Grist TM,Jesmanowicz A,Kneeland JB,Froncisz W,Hyde JS

更新日期：1988-03-01 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

authors： Wurnig MC,Donati OF,Ulbrich E,Filli L,Kenkel D,Thoeny HC,Boss A

更新日期：2015-11-01 00:00:00

abstract：PURPOSE:Going to ultrahigh field MRI (e.g., 7 Tesla [T]), the nonuniformity of the B1+ field and the increased radiofrequency (RF) power deposition become challenging. While surface coils improve the power efficiency in B1+, its field remains nonuniform. In this work, an RF pulse was designed that uses the slab selecti...

journal_title：Magnetic resonance in medicine

authors： van Kalleveen IM,Boer VO,Luijten PR,Klomp DW

更新日期：2015-08-01 00:00:00

abstract：:A new model of compartmentalized relaxation--that which occurs for spins (protons) exchanging between compartments of different relaxation rates--is presented. This model generalizes previous ones by allowing spatially dependent relaxation within compartments. Solutions for the diffusion-Bloch equations are found via ...

journal_title：Magnetic resonance in medicine

authors： Barsky D,Pütz B,Schulten K

更新日期：1997-05-01 00:00:00

abstract：PURPOSE:To propose a phase error correction scheme for monopolar time-interleaved multi-echo gradient echo water-fat imaging that allows accurate and robust complex-based quantification of the proton density fat fraction (PDFF). METHODS:A three-step phase correction scheme is proposed to address a) a phase term induce...

journal_title：Magnetic resonance in medicine

authors： Ruschke S,Eggers H,Kooijman H,Diefenbach MN,Baum T,Haase A,Rummeny EJ,Hu HH,Karampinos DC

更新日期：2017-09-01 00:00:00

abstract：PURPOSE:A systematic study of the short-term and long-term variability of regional alveolar partial pressure of oxygen tension (pA O2 ) measurements using (3) He magnetic resonance imaging was presented. Additionally, the repeatability of the average evaluated pA O2 was compared with that of the standard pulmonary func...

journal_title：Magnetic resonance in medicine

authors： Hamedani H,Kadlecek SJ,Ishii M,Emami K,Kuzma NN,Xin Y,Rossman M,Rizi RR

更新日期：2013-12-01 00:00:00

abstract：:For patients with impaired breath-hold capacity and/or arrhythmias, real-time cine MRI may be more clinically useful than breath-hold cine MRI. However, commercially available real-time cine MRI methods using parallel imaging typically yield relatively poor spatio-temporal resolution due to their low image acquisition...

journal_title：Magnetic resonance in medicine

authors： Feng L,Srichai MB,Lim RP,Harrison A,King W,Adluru G,Dibella EV,Sodickson DK,Otazo R,Kim D

更新日期：2013-07-01 00:00:00

abstract：:In rapidly acquired gradient echo images, lipid regions usually appear as areas of high signal intensity. In 2D inflow angiograms processed by the maximum intensity projection algorithm, this high lipid signal may prevent angiographic visualization of some blood vessels. We present a new approach to suppress the lipid...

journal_title：Magnetic resonance in medicine

authors： Doyle M,Matsuda T,Pohost GM

更新日期：1991-09-01 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