Correction for partial volume errors in MR heart perfusion imaging.

abstract：PURPOSE:We propose a constrained optimization approach for designing parallel transmit (pTx) pulses satisfying all regulatory and hardware limits. We study the trade-offs between excitation accuracy, local and global specific absorption rate (SAR), and maximum and average power for small flip-angle pTx (eight channels)...

journal_title：Magnetic resonance in medicine

authors： Guérin B,Gebhardt M,Cauley S,Adalsteinsson E,Wald LL

更新日期：2014-04-01 00:00:00

abstract：:The purpose of this study was to demonstrate the feasibility of dynamic oxygen-enhanced MRI in a clinical setting. We hypothesized that dynamic oxygen enhancement can reflect the regional diffusing capacity of the lung. Ten patients with pulmonary emphysema and seven healthy volunteers were examined with a respiratory...

journal_title：Magnetic resonance in medicine

authors： Ohno Y,Hatabu H,Takenaka D,Van Cauteren M,Fujii M,Sugimura K

更新日期：2002-06-01 00:00:00

abstract：PURPOSE:We sought to develop and test a clinically feasible 1-point Dixon, three-dimensional (3D) radial acquisition strategy to create isotropic 3D MR images of (129)Xe in the airspaces, barrier, and red blood cells (RBCs) in a single breath. The approach was evaluated in healthy volunteers and subjects with idiopathi...

journal_title：Magnetic resonance in medicine

authors： Kaushik SS,Robertson SH,Freeman MS,He M,Kelly KT,Roos JE,Rackley CR,Foster WM,McAdams HP,Driehuys B

更新日期：2016-04-01 00:00:00

abstract：PURPOSE:To develop and validate a method for choosing the optimal two-dimensional CAIPIRINHA kernel for subtraction contrast-enhanced MR angiography (CE-MRA) and estimate the degree of image quality improvement versus that of some reference acceleration parameter set at R ≥ 8. METHODS:A metric based on patient-specifi...

journal_title：Magnetic resonance in medicine

authors： Weavers PT,Borisch EA,Riederer SJ

更新日期：2015-06-01 00:00:00

abstract：PURPOSE:Spectrally selective "prewinding" radiofrequency pulses can counteract B0 inhomogeneity in steady-state sequences, but can only prephase a limited range of off-resonance. We propose spectral-spatial small-tip angle prewinding pulses that increase the off-resonance bandwidth that can be successfully prephased by...

journal_title：Magnetic resonance in medicine

authors： Williams SN,Nielsen JF,Fessler JA,Noll DC

更新日期：2018-03-01 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：:We have obtained high-field (11.7 Tesla), high-resolution carbon-13 solid-state "magic-angle" sample-spinning nuclear magnetic resonance (NMR) spectra of a variety of phospholipids, sphingolipids, myelin and white matter samples, resolving and assigning over 40 resonances in the spectra of human and bovine myelin. The...

journal_title：Magnetic resonance in medicine

authors： Husted C,Montez B,Le C,Moscarello MA,Oldfield E

更新日期：1993-02-01 00:00:00

abstract：:Follow-up T(1)-weighted 3D gradient-echo MRI (2.35 T) of murine brain in vivo (N = 5) at 120 microm isotropic resolution revealed spatially distinct signal increases 6-48 hr after subcutaneous application of MnCl(2) (20 mg/kg). The effects result from a shortening of the water proton T(1) relaxation time due to the pr...

journal_title：Magnetic resonance in medicine

authors： Watanabe T,Natt O,Boretius S,Frahm J,Michaelis T

更新日期：2002-11-01 00:00:00

abstract：:A method of post-processing to enhance the image resolution of the distribution of free radical molecules obtained with continuous-wave electron paramagnetic resonance (CW-EPR) imaging is reported. The low spatial resolution of EPR imaging, which has created difficulties in biomedical applications, was overcome by the...

journal_title：Magnetic resonance in medicine

authors： Ikebata Y,Sato-Akaba H,Aoyama T,Fujii H,Itoh K,Hirata H

更新日期：2009-09-01 00:00:00

abstract：PURPOSE:Myocardial effective relaxation time T2* is commonly regarded as a surrogate for myocardial tissue oxygenation. However, it is legitimate to assume that there are multiple factors that influence T2*. To this end, this study investigates the relationship between T2* and cardiac macromorphology given by left vent...

journal_title：Magnetic resonance in medicine

authors： Huelnhagen T,Hezel F,Serradas Duarte T,Pohlmann A,Oezerdem C,Flemming B,Seeliger E,Prothmann M,Schulz-Menger J,Niendorf T

更新日期：2017-06-01 00:00:00

abstract：:The ultra-fast application of the RARE experiment is described in detail, with special emphasis on its multifarious applications with preparation experiments that produce transverse magnetization. The factors affecting the temporal evolution of the magnetization during the experiment are described, and the implication...

journal_title：Magnetic resonance in medicine

authors： Norris DG,Börnert P,Reese T,Leibfritz D

更新日期：1992-09-01 00:00:00

abstract：:Proton magnetic resonance spectroscopy ((1)H MRS) was used to determine brain temperature in healthy volunteers. Partially water-suppressed (1)H MRS data sets were acquired at 3T from four different gray matter (GM)/white matter (WM) volumes. Brain temperatures were determined from the chemical-shift difference betwee...

journal_title：Magnetic resonance in medicine

authors： Childs C,Hiltunen Y,Vidyasagar R,Kauppinen RA

更新日期：2007-01-01 00:00:00

abstract：:This paper describes a technique for characterizing the gradient subsystem of a magnetic resonance (MR) system. The technique uses a Fourier-transform analysis to directly measure the k-space trajectory produced by an arbitrary gradient waveform. In addition, the method can be easily extended to multiple dimensions an...

journal_title：Magnetic resonance in medicine

authors： Alley MT,Glover GH,Pelc NJ

更新日期：1998-04-01 00:00:00

abstract：:T(2) -weighted, cardiac magnetic resonance imaging (T(2) w CMR) can be used to noninvasively detect and quantify the edematous region that corresponds to the area at risk (AAR) following myocardial infarction (MI). Previously, CMR has been used to examine structure and function in mice, expediting the study of genetic...

journal_title：Magnetic resonance in medicine

authors： Beyers RJ,Smith RS,Xu Y,Piras BA,Salerno M,Berr SS,Meyer CH,Kramer CM,French BA,Epstein FH

更新日期：2012-01-01 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

authors： Peters DC,Lederman RJ,Dick AJ,Raman VK,Guttman MA,Derbyshire JA,McVeigh ER

更新日期：2003-02-01 00:00:00

abstract：:T2 measurements of 31P NMR signals of ATP using the Hahn 90 degrees-180 degrees spin-echo sequence imply difficulties whenever the 180 degrees pulse angle is not completely perfect. The reason for this finding is the crucial influence of the J-couplings of the ATP signals which result in intensity modulations and cons...

journal_title：Magnetic resonance in medicine

authors： Jung WI,Straubinger K,Bunse M,Widmaier S,Schick F,Küper K,Dietze G,Lutz O

更新日期：1993-07-01 00:00:00

abstract：:The accuracy of perfusion measurements using dynamic, susceptibility-weighted, contrast-enhanced MRI depends on estimating contrast agent concentration in an artery, i.e., the arterial input function. One of the difficulties associated with obtaining an arterial input function are partial volume effects when both bloo...

journal_title：Magnetic resonance in medicine

authors： Patil V,Johnson G

更新日期：2013-04-01 00:00:00

abstract：:Parallel excitation is being studied intensively for applications in MR imaging and in particular for selecting arbitrary shapes as regions of interest. In this work, parallel excitation was applied to arbitrarily shaped voxel selection in spectroscopy and investigated for different excitation k-space trajectories (ra...

journal_title：Magnetic resonance in medicine

authors： Snyder J,Haas M,Hennig J,Zaitsev M

更新日期：2012-02-01 00:00:00

abstract：:Fitting a model to an experimental spectrum is a difficult nonlinear estimation problem. The solution presented here is to start an iterative search procedure sufficiently close to the optimal model parameter set. This is achieved by providing tissue-dependent a priori peak information and by a novel correlation metho...

journal_title：Magnetic resonance in medicine

authors： Burger C,McKinnon G,Buchli R,Boesiger P

更新日期：1991-10-01 00:00:00

abstract：PURPOSE:To improve signal-to-noise ratio (SNR) for high-resolution spectroscopic imaging using a subspace-based technique known as SPectroscopic Imaging by exploiting spatiospectral CorrElation (SPICE). METHODS:The proposed method is based on a union-of-subspaces model of MRSI signals, which exploits the partial separ...

journal_title：Magnetic resonance in medicine

authors： Ma C,Lam F,Ning Q,Johnson CL,Liang ZP

更新日期：2017-02-01 00:00:00

abstract：PURPOSE:To investigate the heating induced by (pseudo)-continuous arterial spin labeling ((p)CASL) sequences in vivo at 9.4T and to evaluate the benefit of a dedicated labeling coil. METHODS:Temperature was measured continuously in the brain, neck, and rectum of 9 rats with fiber-optic temperature probes while running...

journal_title：Magnetic resonance in medicine

authors： Hirschler L,Collomb N,Voiron J,Köhler S,Barbier EL,Warnking JM

更新日期：2020-01-01 00:00:00

abstract：PURPOSE:To validate an automatic algorithm for offline T2* measurements, providing robust, vendor-independent T2*, and uncertainty estimates for iron load quantification in the heart and liver using clinically available imaging sequences. METHODS:A T2* region of interest (ROI)-based algorithm was developed for robustn...

journal_title：Magnetic resonance in medicine

authors： Bidhult S,Xanthis CG,Liljekvist LL,Greil G,Nagel E,Aletras AH,Heiberg E,Hedström E

更新日期：2016-04-01 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：PURPOSE:Simultaneous brain and spinal cord functional MRI is emerging as a new tool to study the central nervous system but is challenging. Poor B0 homogeneity and small size of the spinal cord are principal obstacles to this nascent technology. Here we extend a dynamic shimming approach, first posed by Finsterbusch, b...

journal_title：Magnetic resonance in medicine

authors： Islam H,Law CSW,Weber KA,Mackey SC,Glover GH

更新日期：2019-02-01 00:00:00

abstract：:The proton T(1) was measured at 132 μT in ex vivo prostate tissue specimens from radical prostatectomies of 35 patients with prostate cancer. Each patient provided two specimens. The NMR and MRI measurements involved proton repolarization, a field of typically 150 mT and detection of the 5.6-kHz signal with a supercon...

journal_title：Magnetic resonance in medicine

authors： Busch S,Hatridge M,Mößle M,Myers W,Wong T,Mück M,Chew K,Kuchinsky K,Simko J,Clarke J

更新日期：2012-04-01 00:00:00

abstract：PURPOSE:Cardiac T1 mapping has become an increasingly important imaging technique, contributing novel diagnostic options. However, currently utilized methods are often associated with accuracy problems because of heart rate variations and cardiac arrhythmia, limiting their value in clinical routine. This study aimed to...

journal_title：Magnetic resonance in medicine

authors： Gensler D,Salinger T,Düring M,Lorenz K,Jahns R,Wech T,Frantz S,Ertl G,Jakob PM,Nordbeck P

更新日期：2019-03-01 00:00:00

abstract：PURPOSE:To improve the quality and speed of electron paramagnetic resonance imaging (EPRI) acquisition by combining a uniform sampling distribution with spinning gradient acquisition. THEORY AND METHODS:A uniform sampling distribution was derived for spinning gradient EPRI acquisition (uniform spinning sampling, USS) ...

journal_title：Magnetic resonance in medicine

authors： Johnson DH,Ahmad R,Liu Y,Chen Z,Samouilov A,Zweier JL

更新日期：2014-02-01 00:00:00

abstract：PURPOSE:To accelerate dynamic MR applications using infimal convolution of total generalized variation functionals (ICTGV) as spatio-temporal regularization for image reconstruction. THEORY AND METHODS:ICTGV comprises a new image prior tailored to dynamic data that achieves regularization via optimal local balancing b...

journal_title：Magnetic resonance in medicine

authors： Schloegl M,Holler M,Schwarzl A,Bredies K,Stollberger R

更新日期：2017-07-01 00:00:00

abstract：:A new k-space direct matrix inversion (DMI) method is proposed here to accelerate non-Cartesian SENSE reconstructions. In this method a global k-space matrix equation is established on basic MRI principles, and the inverse of the global encoding matrix is found from a set of local matrix equations by taking advantage ...

journal_title：Magnetic resonance in medicine

authors： Qian Y,Zhang Z,Wang Y,Boada FE

更新日期：2006-08-01 00:00:00

abstract：:Velocity-encoded phase contrast imaging is being used increasingly in clinical imaging for quantization of blood flow. In this study, the accuracy and precision of ascending aorta flow measurements were found to depend on several subtle aspects of the scan prescription and image analysis. While the usual scan paramete...

journal_title：Magnetic resonance in medicine

authors： Buonocore MH,Bogren H

更新日期：1992-07-01 00:00:00