Abstract:
:Head motion is a fundamental problem in functional magnetic resonance imaging and is often a limiting factor in its clinical implementation. This work presents a rigid-body motion correction strategy for echo-planar imaging sequences that uses micro radiofrequency coil "active markers" for real-time, slice-by-slice prospective correction. Before the acquisition of each echo-planar imaging-slice, a short tracking pulse-sequence measures the positions of three active markers integrated into a headband worn by the subject; the rigid-body transformation that realigns these markers to their initial positions is then fed back to dynamically update the scan-plane, maintaining it at a fixed orientation relative to the head. Using this method, prospectively-corrected echo-planar imaging time series are acquired on volunteers performing in-plane and through-plane head motions, with results demonstrating increased image stability over conventional retrospective image-realignment. The benefit of this improved image stability is assessed in a blood oxygenation level dependent functional magnetic resonance imaging application. Finally, a non-rigid-body distortion-correction algorithm is introduced to reduce the remaining signal variation.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Ooi MB,Krueger S,Muraskin J,Thomas WJ,Brown TRdoi
10.1002/mrm.22780subject
Has Abstractpub_date
2011-07-01 00:00:00pages
73-81issue
1eissn
0740-3194issn
1522-2594journal_volume
66pub_type
杂志文章abstract::A novel ultra-rapid gradient echo (URGE) NMR imaging technique is introduced, which is capable of continuous high resolution 3D scanning while neither subject to fast gradient switching nor excessive RF power deposition. Sampling free induction decays instead of creating spin echoes enables maintaining a workable stea...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910330123
更新日期:1995-01-01 00:00:00
abstract::Problems with in vivo proton spectroscopy include strong water and lipid signals, and the very complicated structures of the spectra. Multiple-quantum experiments can be designed to overcome these difficulties. Using a volume selective refocusing technique, one can demonstrate how multiple-quantum experiments can be p...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910060311
更新日期:1988-03-01 00:00:00
abstract::Maximal intensity projection (MIP) is routinely used to view MRA and other volumetric angiographic data. The straightforward implementation of MIP is ray casting that traces a volumetric data set in a computationally expensive manner. This article reports a fast MIP algorithm using shear warp factorization and reduced...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10114
更新日期:2002-04-01 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::The dependence of 1/T1 on the magnetic field strength (the relaxation dispersion) has been measured at 37 degrees C on autopsy samples of human brain gray and white matter at field strengths corresponding to proton Larmor frequencies between 10 kHz and 50 MHz (0.0002-1.2 T). Additional measurements of 1/T1 and 1/T2 ha...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910160212
更新日期:1990-11-01 00:00:00
abstract::The combination of a frequency nonselective excitation suppression method (1331 sequence) with selective excitation followed by gradient-induced dephasing of water transverse magnetization yielded suppression ratios of greater than 10,000:1. The need for gradient preemphasis and correction of B0 field shifts is discus...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910090114
更新日期:1989-01-01 00:00:00
abstract:PURPOSE:To test the feasibility of using the SPICE (SPectroscopic Imaging by exploiting spatiospectral CorrElation) technique, which uses the partial separability of spectroscopic data, for high resolution hyperpolarized (HP) 13 C spectroscopic imaging. METHODS:Numerical simulations were performed to investigate the i...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27061
更新日期:2018-08-01 00:00:00
abstract::Alternate methods to quantify mitochondrial activity or function have been extensively used for studying insulin resistance and type 2 diabetes mellitus, namely saturation transfer and phosphocreatine (PCr) recovery. As these methods are in fact determining different parameters, this study aimed to compare saturation ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.23095
更新日期:2012-04-01 00:00:00
abstract::The incorporation of RF coils into the tips of intravascular devices has been shown to enable the localization of catheters and guidewires under MR guidance. Furthermore, such coils can be used for endoluminal imaging. The long cable required to connect the coil with the scanner input inadvertently acts as a dipole an...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(200004)43:4<615::aid-mrm19
更新日期:2000-04-01 00:00:00
abstract::The utility of MRI using magnetization transfer (MT) enhanced pulse sequences to diagnose hepatic cirrhosis in a rat model was investigated. Hepatic T1 was measured with and without MT off-resonance RF pulses in 17 treated and six control rats. The livers were evaluated histologically, and the hydroxyproline content q...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910310513
更新日期:1994-05-01 00:00:00
abstract::Cirrhosis is an important and growing public health problem, affecting millions of Americans and many more people internationally. A pathological hallmark of the progression to cirrhosis is the development of liver fibrosis, so that monitoring the appearance and progression of liver fibrosis can be used to guide thera...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22785
更新日期:2011-04-01 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::Multiple receivers can be utilized to enhance the spatiotemporal resolution of MRI by employing the parallel imaging technique. Previously, we have reported the L-curve Tikhonov regularization technique to mitigate noise amplification resulting from the geometrical correlations between channels in a coil array. Nevert...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21356
更新日期:2007-10-01 00:00:00
abstract::An eight-channel receive-only brain coil and table-top detunable volume transmit coil were developed and tested at 7 T for human imaging. Optimization of this device required attention to sources of interaction between the array elements, between the transmit and receive coils and minimization of common mode currents ...
journal_title:Magnetic resonance in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/mrm.20547
更新日期:2005-07-01 00:00:00
abstract:PURPOSE:To optimize and investigate the influence of bipolar gradients for flow suppression in metabolic quantification of hyperpolarized 13 C chemical shift imaging (CSI) of mouse liver at 9.4 T. METHODS:The trade-off between the amount of flow suppression using bipolar gradients and T2* effect from static spins was ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26578
更新日期:2017-11-01 00:00:00
abstract:PURPOSE:To investigate the effect of realistic microstructural geometry on the susceptibility-weighted MR signal in white matter (WM), with application to demyelination. METHODS:Previous work has modeled susceptibility-weighted signals under the assumption that axons are cylindrical. In this study, we explored the imp...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26689
更新日期:2018-01-01 00:00:00
abstract::31P NMR spectroscopy was used to study renal allografts in rats subjected to allograft rejection, cyclosporine toxicity, ischemia, and ureteral obstruction. Parameters of relative peak areas and intracellular pH were accurately distinguished among the different causes of graft dysfunction. Ureteral obstruction was cle...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910050405
更新日期:1987-10-01 00:00:00
abstract:PURPOSE:The purpose of this study was to investigate the feasibility of in vivo imaging of human pancreatic ductal cells by OATP1B3 reporter gene under MRI. METHODS:A human cell line (PANC-1) derived from the pancreatic ductal epithelium was used in this study. After transduction of OATP1B3, the cellular physiological...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27749
更新日期:2019-08-01 00:00:00
abstract::Optimal control theory has been applied in the past for the design of RF pulses for selective excitation. This was the outcome of having established the controllability of the MR spin system for the selective excitation problem. "Minimum distance" was the main formulation used for the solution. Because of their robust...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910360311
更新日期:1996-09-01 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::Phase-sensitive inversion-recovery (PSIR) imaging may provide enhanced T(1) contrast. However, clinical implementation of PSIR imaging is hindered because image reconstruction with this method often lacks robustness and requires manual intervention, particularly for data acquired in multiple slices and with phased-arr...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20414
更新日期:2005-04-01 00:00:00
abstract::Measurement of myocardial and brain perfusion when using exogenous contrast agents (CAs) such as gadolinium-DTPA (Gd-DTPA) and MRI is affected by the diffusion of water between compartments. This water exchange may have an impact on signal enhancement, or, equivalently, on the longitudinal relaxation rate, and could t...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1188
更新日期:2001-08-01 00:00:00
abstract::Specific absorption rate management and excitation fidelity are key aspects of radiofrequency pulse design for parallel transmission at ultra-high magnetic field strength. The design of radiofrequency pulses for multiple channels is often based on the solution of regularized least-squares optimization problems for whi...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.23004
更新日期:2012-01-01 00:00:00
abstract::With the advent of breath-hold MR cardiac imaging techniques, the minimization of TR and TE for oblique planes has become a critical issue. The slew rates and maximum currents of gradient amplifiers limit the minimum possible TR and TE by adding dead-periods to the pulse sequences. We propose a method of designing gra...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910320613
更新日期:1994-12-01 00:00:00
abstract::We have noninvasively produced low-resolution, quantitative nuclear magnetic resonance images of cerebral blood flow in 2-ml voxels in eight cats. Typical signal-to-noise of 4 to 1 was obtained in cerebral voxels in 16.5-s epochs. Mean flow during normocapnia (paCO2 = 39 +/- 4 mm Hg) and hypercapnia (paCO2 = 62 +/- 4 ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910280105
更新日期:1992-11-01 00:00:00
abstract:PURPOSE:Our clinical understanding of the relationship between 3D bone morphology and knee osteoarthritis, as well as our ability to investigate potential causative factors of osteoarthritis, has been hampered by the time-intensive nature of manually segmenting bone from MR images. Thus, we aim to develop and validate ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27920
更新日期:2020-01-01 00:00:00
abstract:PURPOSE:Multi-echo spin-echo (MSE) transverse relaxometry mapping using multi-component models is used to study disease activity in neuromuscular disease by assessing the T2 of the myocytic component (T2water ). Current extended phase graph algorithms are not optimized for fat fractions above 50% and the effects of ina...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28290
更新日期:2020-11-01 00:00:00
abstract:PURPOSE:To present the results of the first human spinal cord in vivo MRI scans at 9.4T. METHODS:A human brain coil was used to image the human spinal cord at 9.4T. All anatomical images were acquired with a T2 *-weighted gradient-echo sequence. A comparison of the influence of four different B0 shimming routines on t...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28455
更新日期:2021-02-01 00:00:00
abstract::Cortical spreading depression (CSD) was visualized using manganese-enhanced MRI (MEMRI) following topical application of KCl to the exposed rat cortex. MEMRI signal increase in the ipsilateral cortex relative to the contralateral control region was 60 +/- 30% following two KCl applications. MEMRI signal increase for a...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20438
更新日期:2005-04-01 00:00:00
abstract::Adipose tissue as well as other depots of fat (triglycerides) are increasingly being recognized as active contributors to the human function and metabolism. In addition to the fat concentration, also the fatty acid chemical composition (FAC) of the triglyceride molecules may play an important part in diseases such as ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章,评审
doi:10.1002/mrm.28471
更新日期:2021-01-01 00:00:00