Advantages of using multiple-echo image combination and asymmetric triangular phase masking in magnetic resonance venography at 3 T

Brainovich, Valentina; Sabatini, Umberto; Hagberg, Gisela E.

doi:10.1016/j.mri.2008.05.006

Cited by 23 publications

(17 citation statements)

References 37 publications

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“…Higher signals are obtained at shorter TEs, and higher susceptibility eŠects are achieved at longer TEs. 2,3 In addition, multiple acquisitions result in an increased number of signals averaged and thus a decrease in random noise eŠects. Use of single-echo-long TE scans to achieve a strong susceptibility eŠect lead to geometric distortion and chemical shift artifacts.…”

Section: Discussionmentioning

confidence: 99%

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Clinical Value of 3D T2-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2-weighted Imaging and 3D Phase-sensitive MR Imaging

Kunimatsu¹,

Suzuki²,

Hagiwara³

et al. 2012

magn reson med sci

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Susceptibility-weighted angiography (SWAN) is a state-of-the-art 3-dimensional (3D) T 2 *-weighted imaging (T 2 *WI) technique with multiple echo acquisitions, but its clinical utility remains to be determined. We compared the utility of susceptibility-weighting sequences among SWAN, 3D phase-sensitive magnetic resonance (MR) imaging (PSI), and conventional 2-dimensional (2D) T 2 * WI in routine clinical practice. Our results indicate that SWAN can achieve susceptibility weighting more eŠectively than conventional 2D T 2 *WI and as eŠectively as PSI and requires a much shorter scan time than PSI.

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Section: Discussionmentioning

confidence: 99%

“…Higher signals are obtained at shorter TEs, and higher susceptibility eŠects are achieved at longer TEs. 2,3 SWAN uses only magnitude and not phase information of MR signals from the tissues and theoretically oŠers a diŠerent tissue contrast from 3D susceptibilityweighted MR imaging, which utilizes both magnitude and phase information.…”

Section: Introductionmentioning

confidence: 99%

Clinical Value of 3D T2-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2-weighted Imaging and 3D Phase-sensitive MR Imaging

Kunimatsu¹,

Suzuki²,

Hagiwara³

et al. 2012

magn reson med sci

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“…For example, the effective transverse relaxation rate (R 2 ‫ء‬ ), which can be extracted from multiecho gradient-echo data via voxelwise curve fitting, is a metric that scales linearly with iron concentration in the brain. 6 Brainovich et al 7 described a postprocessing scheme for dualecho gradient-echo data. In this scheme, average phase and average magnitude volumes were generated and subsequently used to produce a single SWI volume.…”

mentioning

confidence: 99%

Comparison of Multiecho Postprocessing Schemes for SWI with Use of Linear and Nonlinear Mask Functions

Quinn¹,

Gati²,

Klassen³

et al. 2013

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE:SWI is an MR technique conventionally implemented with single-echo gradient-echo data. The purpose of this study was to compare single-echo SWI processing and 2 multiecho SWI processing schemes: postaverage, where an SWI image is created for each echo and then averaged to create a single volume; and frequency-based, where a SWI image is generated from an average frequency image. Linear and nonlinear mask functions were investigated for all 3 processing schemes.

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“…(Noll et al, 1991). This method was chosen because I hypothesised that phase changes caused by external magnetic fields such as those generated by the heart and imperfect field gradients concentrated at low spatial frequencies (Brainovich et al, 2009;Hagberg et al, 2012). The high-pass filtering can be stated as…”

Section: Methodsmentioning

confidence: 99%

“…The subject's motion relative to the scanner has been reported to be a dominant source of phase noise in MRI signals Brainovich et al, 2009;Petridou et al, 2009;Hagberg et al, 2012). Motion may be caused by physiological processes, such as respiration and cardiac action, and scanner vibration.…”

Section: Experiments 3: Phase Noise Due To Motionmentioning

confidence: 99%

Realistic models for detection of neuronal currents with magnetic resonance imaging

Du¹

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A great challenge facing brain research is to "see" neurons in action at high spatial and temporal resolution in the living human brain. While existing non-invasive techniques, such as electroencephalography (EEG), magnetoencephalography (MEG), and functional magnetic resonance imaging (fMRI), have either poor spatial or temporal resolution, neuronal current MRI (nc-MRI) may hold the potential to revolutionize cognitive neuroscience by imaging neuronal activity at high temporal and spatial resolutions.However, the implementation of nc-MRI using existing instrumentation is yet to be convincingly demonstrated.In this project, I investigated the feasibility of nc-MRI via computer simulations. To allow realistic neuronal current simulations, the laminar cortex model (LCM) was first developed.The LCM incorporates the laminar architecture of the cerebral cortex into a continuum cortex model (previously developed by Wright et al.) to simulate the collective activity of cortical neurons. As validations, the LCM has been used to simulate the local field potentials (LFP) of the primary visual cortex. The LCM produced spontaneous LFPs exhibited frequency-inverse (1/f) power spectrum behaviour. The LCM also captured the fundamental as well as the high order harmonics under intermittent light stimulation.To model neuronal currents, I decomposed the neuronal activity simulated by the LCM into action potentials and postsynaptic potentials. The geometries of dendrites and axons were generated dynamically to account for neuronal morphology diversity. Magnetic fields produced by action potentials and postsynaptic potentials were calculated for the cases of spontaneous and stimulated cortical activity, from which the nc-MRI signal was determined. The MRI signal magnitude change was found to be below currently detectable levels (< 0.1 part-per-million), but signal phase change was potentially detectable (in the order of 0.1 milli-radian). Furthermore, nc-MRI signals were sensitive to temporal and spatial variations in neuronal activity and independent of the intensity of neuronal activation. Synchronous neuronal activity produces large phase changes, up to 1 milliradian, and the signal phase oscillated with neuronal activity.Based on the computer simulation results, I proposed to image oscillatory neuronal currents using a multi-echo spin echo (MESE) and a synchronised multi-echo gradient recalled echo (MEGRE) sequences. A MESE sequence can accumulate phase changes for multiple neuronal activity oscillation periods through applying radio-frequency (RF) -Iexcitation pulses at the times when neuronal magnetic fields change sign. MEGRE sequence could be used to extract neuronal current signal from noisy MRI signals, because neuronal current signal but not blood-oxygen-level dependent (BOLD) effect or noise, varies with neuronal oscillation. Because a MEGRE sequence is capable of acquiring MRI signals at a series of closely-spaced time points, the inherent oscillation of neuronal current signals may potentially be deduced from ...

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Advantages of using multiple-echo image combination and asymmetric triangular phase masking in magnetic resonance venography at 3 T

Cited by 23 publications

References 37 publications

Clinical Value of 3D T2-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2-weighted Imaging and 3D Phase-sensitive MR Imaging

Clinical Value of 3D T2-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2-weighted Imaging and 3D Phase-sensitive MR Imaging

Comparison of Multiecho Postprocessing Schemes for SWI with Use of Linear and Nonlinear Mask Functions

Realistic models for detection of neuronal currents with magnetic resonance imaging

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Advantages of using multiple-echo image combination and asymmetric triangular phase masking in magnetic resonance venography at 3 T

Cited by 23 publications

References 37 publications

Clinical Value of 3D T2*-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2*-weighted Imaging and 3D Phase-sensitive MR Imaging

Clinical Value of 3D T2*-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2*-weighted Imaging and 3D Phase-sensitive MR Imaging

Comparison of Multiecho Postprocessing Schemes for SWI with Use of Linear and Nonlinear Mask Functions

Realistic models for detection of neuronal currents with magnetic resonance imaging

Contact Info

Product

Resources

About

Clinical Value of 3D T2-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2-weighted Imaging and 3D Phase-sensitive MR Imaging

Clinical Value of 3D T2-weighted Imaging with Multi-echo Acquisition: Comparison with Conventional 2D T2-weighted Imaging and 3D Phase-sensitive MR Imaging