Abstract:
:A birdcage coil possesses various intrinsic resonant modes. One of the modes produces sinusoidal current distribution around the rung elements of the birdcage and generates a highly uniform B(1) field in the transverse plane. Another mode is the end-ring resonant mode, in which there are no currents in the rungs of the birdcage, leaving the currents flowing in the top and bottom end-rings. Thus, this mode behaves like a "Helmholtz pair," producing a highly uniform B(1) field along the axis of the birdcage. By combining the sinusoidal resonant mode and the end-ring resonant mode at the same frequency, a quadrature birdcage coil for a vertical B(0) field is made possible. In particular, the coil dimension can be chosen such that the two end-ring loops behave as a Helmholtz pair, assuring the optimized B(1) field uniformity around the coil center region. The coil is well suited for a vertical B(0) MRI system, as both B(1) fields are perpendicular to the vertical B(0) field. To mimic a vertical B(0) field orientation, an existing horizontal bore MRI system was used with the RF coil oriented to simulate a "vertical" B(0) field. This is a report of the successful quadrature implementation of this novel birdcage coil.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Fujita H,Braum WO,Morich MAdoi
10.1002/1522-2594(200010)44:4<633::aid-mrm18>3.0.csubject
Has Abstractpub_date
2000-10-01 00:00:00pages
633-40issue
4eissn
0740-3194issn
1522-2594pii
10.1002/1522-2594(200010)44:4<633::AID-MRM18>3.0.Cjournal_volume
44pub_type
杂志文章abstract::Kinetic analysis with mathematical models has become increasingly important to quantify physiological parameters in computed tomography (CT), positron emission tomography (PET), and dynamic contrast-enhanced MRI (DCE-MRI). The modified Kety/Tofts model and the graphical (Patlak) model have been widely applied to DCE-M...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22819
更新日期:2011-09-01 00:00:00
abstract::The aim of this work was to identify ventricular shape-based biomarkers in MR images to discriminate between patients with Alzheimer's disease (AD) and healthy elderly. Clinical MR images were collected for 58 patients and 28 age-matched healthy controls. After normalizing all the images the ventricular cerebrospinal ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21471
更新日期:2008-02-01 00:00:00
abstract::In this study we utilized manganese-enhanced MRI (MEMRI) to evaluate the in vivo transneuronal efficiency of manganese ion (Mn(2+)) movement as a means to assess overall changes in neuronal function. We designated this extension the manganese transfer index (MTI) value. To evaluate the MTI value as an index of transne...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21648
更新日期:2008-07-01 00:00:00
abstract::Localized 1H NMR homonuclear J editing spectroscopy was used to measure the concentration of 2-pyrrolidinone (PRDN) in the human occipital lobe of five normal and six epileptic subjects taking vigabatrin. PRDN is a lactam cyclization product of gamma-aminobutyric acid (GABA). From a localized volume of 13.5 cm3 in the...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199905)41:5<889::aid-mrm6>
更新日期:1999-05-01 00:00:00
abstract::Phase contrast flow velocity measurements were performed in six healthy volunteers and 30 patients with arteriosclerotic disease. The iliac arteries were investigated in 8 cases and the femoral arteries in 28 cases. In the first 24 patients, 16 evenly distributed data sets were acquired during one cardiac cycle. In th...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910340508
更新日期:1995-11-01 00:00:00
abstract::MnCl(2) was injected intrathecally through the cisterna magna in rats, allowing infusion of divalent manganese ions (Mn(++)) into the CSF space and thence into the brain, without breaking the blood-brain barrier (BBB). Mn(++) uptake and washout dynamics in the brain were measured by serial T(1)-weighted MRI and EPI T(...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20047
更新日期:2004-05-01 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
pub_type: 杂志文章
doi:10.1002/mrm.1910080406
更新日期:1988-12-01 00:00:00
abstract::Imaging delayed hyperenhancement of myocardial infarction is most commonly performed using an inversion recovery (IR) prepared 2D breathhold segmented k-space gradient echo (FGRE) sequence. Since only one slice is acquired per breathhold in this technique, 12-16 successive breathholds are required for complete anatomi...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20061
更新日期:2004-05-01 00:00:00
abstract::Previous theoretical reports described the dependence of interpretation of the observed phase of the NMR signal on the time origin(s) of moment calculations and position's Taylor series expansion. This work provides experimental confirmation of predictions derived from that theory. For accelerative motion, experimenta...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910320111
更新日期:1994-07-01 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
pub_type: 杂志文章
doi:10.1002/mrm.20455
更新日期:2005-05-01 00:00:00
abstract::The purpose of this study was to determine the value of a blood-pool contrast media (NC100150, Nycomed Imaging (now Amersham Health) Oslo, Norway) for evaluation of venous thrombosis of the deep veins of the pelvis and lower extremities. Twelve patients were prospectively evaluated with conventional X-ray venography (...
journal_title:Magnetic resonance in medicine
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1002/mrm.10607
更新日期:2003-11-01 00:00:00
abstract::Proton T(1rho)-dispersion MRI is demonstrated for indirect, in vivo detection of (17)O in the brain. This technique, which may be readily implemented on any clinical MRI scanner, is applied towards high-resolution, quantitative mapping of cerebral blood flow (CBF) in the rat by monitoring the clearance of (17)O-enrich...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10403
更新日期:2003-03-01 00:00:00
abstract::Continuous arterial spin labeling (CASL) was used to obtain an index of cerebral blood flow (ICBF) in the normal mouse brain and in an orthotopic mouse model of human U87 high-grade glioma at 8.5 T. Under the assumption of a constant tissue:blood partition coefficient for water in different tissues, the mean ICBF (n =...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20029
更新日期:2004-05-01 00:00:00
abstract:PURPOSE:To remove nuisance signals (e.g., water and lipid signals) for (1) H MRSI data collected from the brain with limited and/or sparse (k, t)-space coverage. METHODS:A union-of-subspace model is proposed for removing nuisance signals. The model exploits the partial separability of both the nuisance signals and the...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25635
更新日期:2016-02-01 00:00:00
abstract::The eigenimage filter was used to evaluate the results of a MRI study of cerebral ischemia in a rat model. This linear filter segments a desired feature in an image sequence from other features which may interfere with its observation. The animals were imaged temporally, after occlusion of the middle cerebral artery, ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910260207
更新日期:1992-08-01 00:00:00
abstract::This study determines the accuracy and feasibility of using localized spin-lattice (T1) relaxation time measurements from magnetic resonance (MR) images to follow changes in extracellular/intracellular fluid ratios in defined subvolumes of living tissue. A red blood cell suspension was used as a test system and a simp...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910150107
更新日期:1990-07-01 00:00:00
abstract:PURPOSE:MRI-guided thermal ablations require reliable monitoring methods to ensure complete destruction of the diseased tissue while avoiding damage to the surrounding healthy tissue. Based on the fact that thermal ablations result in substantial changes in biomechanical properties, interventional MR elastography (MRE)...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25694
更新日期:2016-03-01 00:00:00
abstract::A novel center-out 3D trajectory for sampling magnetic resonance data is presented. The trajectory set is based on a single Fermat spiral waveform, which is substantially undersampled in the center of k-space. Multiple trajectories are combined in a "stacked cone" configuration to give very uniform sampling throughout...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22918
更新日期:2011-11-01 00:00:00
abstract::A modified Look-Locker acquisition using saturation recovery (MLLSR) for breath-held myocardial T(1) mapping is presented. Despite its reduced dynamic range, saturation recovery enables substantially higher imaging efficiency than conventional inversion recovery T(1) mapping because it does not require time for magnet...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24137
更新日期:2012-03-01 00:00:00
abstract::MRI of hyperpolarized (129)Xe dissolved in pulmonary tissues, and blood has the potential to offer a new tool for regional evaluation of pulmonary gas exchange and perfusion; however, the extremely short T2* and low magnetization density make it difficult to acquire the image. In this study, an ultrashort echo-time se...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24452
更新日期:2013-07-01 00:00:00
abstract::Function and morphology of the cerebral vasculature were studied in the amyloid (Abeta) plaque-containing double-transgenic (TG) B6.PS2APP Alzheimer's disease (AD) mouse model with MRI at an age range of 10 to 17 months. Perfusion, blood volume, and average vessel geometry were assessed in the brain and compared to ag...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21985
更新日期:2009-07-01 00:00:00
abstract:PURPOSE:To present a new method that can simultaneously and efficiently measure T1 and B1 (+) maps using reference region variable flip angle (RR-VFA) imaging. METHODS:Assuming T1 relaxation time in a reference region such as fat is well characterized, and the reference region sufficiently covers smoothly varying B1 (...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24904
更新日期:2013-10-01 00:00:00
abstract::In this study undersampled projection reconstruction (PR) was used for rapid catheter imaging in the heart, employing steady-state free precession (SSFP) contrast. Active catheters and phased-array coils were used for combined imaging of anatomy and catheter position in swine. Real-time imaging of catheter position wa...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10390
更新日期:2003-02-01 00:00:00
abstract::A novel multiple quantum filtering method is proposed that uses a doubly selective pulse termed Delays Alternating with Nutations for Tailored Excitation (DANTE) for multiple quantum preparation. This method selectively prepares GABA-3 and GABA-4 into a multiple quantum state and suppresses all other resonances at 3.0...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10104
更新日期:2002-03-01 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
pub_type: 杂志文章
doi:10.1002/mrm.1910370404
更新日期:1997-04-01 00:00:00
abstract::Noninvasive molecular imaging of angiogenesis could play a critical role in the clinical management of peripheral vascular disease patients. The alpha(nu)beta(3)-integrin, a well-established biomarker of neovascular proliferation, is an ideal target for molecular imaging of angiogenesis. This study investigates whethe...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22447
更新日期:2010-08-01 00:00:00
abstract::A new approach to autocalibrating, coil-by-coil parallel imaging reconstruction, is presented. It is a generalized reconstruction framework based on self-consistency. The reconstruction problem is formulated as an optimization that yields the most consistent solution with the calibration and acquisition data. The appr...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22428
更新日期:2010-08-01 00:00:00
abstract::Magnetic resonance images of the lungs of a guinea pig have been produced using hyperpolarized helium as the source of the MR signal. The resulting images are not yet sufficiently optimized to reveal fine structural detail within the lung, but the spectacular signal from this normally signal-deficient organ system off...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910330219
更新日期:1995-02-01 00:00:00
abstract::Myocardial MR first-pass perfusion time courses are contaminated by signals from the ventricles (spillover) as a consequence of partial volume effects and motion. An early increase in the signal intensity from the myocardium is an indicator of contamination. This contamination leads to under- or overestimation of perf...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20015
更新日期:2004-04-01 00:00:00
abstract::In this work, a new double quantum filter for glutathione (GSH) editing is introduced, combined with the point-resolved spectroscopy localization sequence (PRESS), and demonstrated in vivo. Compared to the conventional double quantum coherence filter, the new filter has two major advantages. First, it eliminates the n...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20788
更新日期:2006-03-01 00:00:00