Journal of Magnetic Resonance - Research Outputs - Lund

Journal of Magnetic Resonance - Forskningsoutput - Lunds

470-476. ISSN 0740-3194 Full text not available from this repository. (Request a copy) Abstract Phase-contrast (PC) MRI is a non-invasive technique to assess cardiovascular blood flow. However, this technique is not accurate in the case of atherosclerotic disease and vascular and valvular stenosis due to intravoxel dephasing secondary to disturbed blood flow, flow recirculation, and turbulence distal to the narrowing, resulting in flow-related artifacts. Background: Recently a small cohort study demonstrated that intravoxel incoherent motion (IVIM) diffusion MRI can detect early stage liver fibrosis. Using modified IVIM data acquisition parameters, the current study aims to confirm this finding.

Intravoxel dephasing mri

27 May 2016 Magnetic resonance imaging (MRI) is a versatile and useful imaging modality In MRI, intravoxel dephasing causes signal loss in regions of Steady-state free precession (SSFP) imaging is a magnetic resonance imaging ( MRI) The refocusing mechanism fails if intravoxel dephasing exceeds over ± 180º manifest by band-like artifacts. During the last decade modern scanners have& 14 Jul 2013 Complexity of aortic flow pattern and intravoxel dephasing Practical value of cardiac magnetic resonance imaging for clinical quantification of MR vessel wall imaging refers to MRI techniques used to evaluate for disease pulse) and/or intravoxel dephasing (spins moving with different velocities due to Magnetic resonance imaging is utilized as an important tool in radiation oncol- refocus dephasing due to main magnetic field inhomogeneities or spin-spin Spatial Localization Mri Instrument Overview Gradient Dephasing And Rephasing Gradient Echoes And Intravoxel Phase Dispersion Factors Which Affect Eddy Current Correction in PC-MRI: An Analysis of Local and Global Static motion artifacts, chemical shift effects, intravoxel dephasing effects, gradient-. 18: Intravoxel dephasing helps in distinguishing arachnoid cysts from webs. Findings and procedure details. Commonly encountered artifacts on MRI due to CSF (increasing matrix/decreasing slice thickness) can reduce the intravoxel dephasing Magnetic resonance imaging of metal artifact reduction sequences in the 5.

During the last decade modern scanners have overcome these limitations making True FISP a viable and useful sequence on most mid- and high-field systems. Intravoxel incoherent motion (IVIM) imaging is a concept and a method initially introduced and developed by Le Bihan et al. to quantitatively assess all the microscopic translational motions that could contribute to the signal acquired with diffusion MRI. Experiments were performed with a 0.2 T magnet on a network of small interacting air-filled cylinders along with Magnetic resonance imaging (MRI) simulations integrating intravoxel dephasing.

Journal of Magnetic Resonance - Forskningsoutput - Lunds

The simulator consists of two parts. 2006-07-08 mechanism is intravoxel dephasing: Luminal blood contains spins travelingatvaryingvelocities(eg,duetolaminarflow).Betweenthe time of excitation and readout, these spins move through the mag-netic field gradients at different rates, resulting in intravoxel phase dispersion with signal loss.8 One may further exploit the intravoxel Objective Characterization of magnetic susceptibility artefacts with assessment of the gradient-echo signal decay function of echo time, pixel size, and object geometry in the case of air-filled cylinders embedded in water. Materials and methods 2004-08-01 While a T1 weighted MRI pulse sequence is diffusion sensitive, thereby accelerating intravoxel incoherent motion (IVIM) signal loss. Dephasing is proportional to the square of the time (diffusion time) during which the gradients are switched on and the strength of the applied gradient field.

Software Simulation of Magnetic Resonance Imaging - Ca Da Alt N

0.2 T magnet on a network of small interacting air-filled cylinders along with Magnetic resonance imaging (MRI) simulations integrating intravoxel dephasing. MRI. Magnetic resonance imaging. NMR. Nuclear magnetic resonance. FOV. Field of view. RO ated with intravoxel dephasing that over the course of a. 18 Oct 2010 Summary: Since the first 3 Tesla (3T) magnetic resonance imaging Decreases in voxel size can also limit the amount of intravoxel dephasing.

29. Chemical fat-saturation should be avoided. intravoxel dephasing phase difference between stationary nuclei and flowing nuclei in voxel, nuclei insame voxel are out of phase with each other, results inredirection of signal amplitude flow phenomena compensation These symmetrical gradient lobes have the sole purpose of enhancing dephasing of spins, thereby accelerating intravoxel incoherent motion (IVIM) signal loss.
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Cite as: http://hdl.handle.net/11858/00-001M-0000-0013-026C-B By decomposing the T2 * MRI technology further into 2 steps, 6 3D convolution for tissue magnetization and intravoxel dephasing for T2 * image formation, we will show that the T2 * MRI nonlinearity is largely due to the T2 * magnitude and phase calculations from a T2 * complex image. 2019-02-15 · Beside random capillaries blood flow may also experience incoherent intravoxel dephasing in larger vessels, considering that laminar flow (or even more turbulent flow) leads to a distribution of velocities within the vessel lumen and to an IVIM signal attenuation which could be much larger than the perfusion-driven IVIM effect. Part 3 of 4The yellow arrow represents the sum of the individual vectors (this is the actual MRI signal that can be measured).It decreases as dephasing gets Intravoxel Dephasing due to Wave Gradients. This article assumes prior knowledge of Wave-CAIPI[1]. In particular, this article attempts to describe the methodology used to generate Figure 9 of [1].

Since the excitation pulse is "Balanced" means that the net gradient-induced dephasing over a TR interval is zero.
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Software Simulation of Magnetic Resonance Imaging - Ca Da Alt N

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Displacement encoding with stimulated echoes (DENSE) with a meta-DENSE readout and RF phase cycling to suppress the STEAM anti-echo is described for reducing intravoxel dephasing signal loss.

The last artifact to consider is the dephasing of spins within a given voxel over the duration of the EPI sampling trajectory. All spins are completely in phase at the instant of the spin echo, but immediately begin to dephase at a rate proportional to the amount of magnetic field inhomogeneity within the voxel. Signal decay due to susceptibility-induced intravoxel dephasing on multiple air-filled cylinders: MRI simulations and experiments. Magnetic Resonance Materials in Physics, Biology and Medicine, 21 (4), 261-271.