Denis Le Bihan, father of modern diffusion imaging, coined the term intravoxel incoherent motion (IVIM) in the 1980s to refer to the microscopic translation of water molecules within a voxel during an MR experiment. When gradients are applied during evolution of the MR signal, IVIM causes spin dephasing …

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.

MATERIALS AND METHODS: 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. Signal decay over echo time was assessed at different pixel sizes on real and simulated images. Since magnetic properties of changing blood oxygenation (Y) affect the tissue water MRI signal through intravoxel spin dephasing (Kennan et al., 1994), changes in Y can be differentially captured with the transverse relaxation rates as measured by gradient-echo R 2 * and spin-echo (R 2). of MR phenomena due to intra-voxel dephasing is essential for many common MR applications such as spin echo imaging, stimulated echo imaging, high resolution imaging, and gradient spoiling schemes. Because the commonly-available models of human anatomy are generally limited in voxel Jim Pipe, in Diffusion MRI (Second Edition), 2014.

How to decrease intravoxel dephasing and increase SNR: Decrease the voxel size (increase spatial resolution), either by increasing the matrix ( trade-off: will reduce signal-to-noise ratio [ SNR ]) or by reducing the FOV ( trade-off: may cause wraparound). Intravoxel dephasing related to turbulence Accumulation of positive phase shift over the course of the scan Fat-saturation pulses as used in time-of-flight imaging Inflow of unsaturated blood into the slice after the initial 90-degree pulse Flow-related enhancement is caused by 'naive' blood entering the slice. directions result in more rapid dephasing and signal loss termed “intravoxel dephasing.” A commonly encountered CSF flow artifact is the signal void in the dorsal subarachnoid space on sagittal T2-weighted images of the thoracic spine (Fig. 13). This artifact is due to a combination of the respiratory and cardiac- 2015-04-06 Normal CSF has inherent MRI properties of low signal intensity on T1-weighted sequences and high signal intensity on T2-weighted The varied flow velocities and directions result in more rapid dephasing and signal loss termed “intravoxel dephasing. Turbulence dephasing can be reduced by shorter TE sequences and smaller voxel The refocusing mechanism fails if intravoxel dephasing exceeds ±180º manifest by band-like artifacts.

Decreasing the voxel size (increasing matrix/decreasing slice thickness) can reduce the intravoxel dephasing caused by magnetic susceptibility. • Increasing the

This is a consequence of the fact that in 2019-09-30 · At very low diffusion weighting the diffusion MRI signal is affected by intravoxel incoherent motion (IVIM) caused by dephasing of magnetization due to incoherent blood flow in capillaries or other sources of microcirculation. 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. Signal decay due to susceptibility-induced intravoxel dephasing on multiple air-ﬁlled cylinders: MRI simulations and experiments François De Guio · Hugues Benoit-Cattin · In MRI, particularly turbulent blood ﬂow gives rise to intravoxel dephasing, where spins within a voxel have accrued different amounts of phase leading to reduced M xy magni-tude.

The varied flow velocities and directions result in more rapid dephasing and signal loss termed “intravoxel dephasing.” A commonly encountered CSF flow artifact is the signal void in the dorsal subarachnoid space on sagittal T2-weighted images of the thoracic spine ( Fig. 13 ).

Dephasing increases with voxel size so that one simple method of reducing the effect is to use thin slices. Intravoxel dephasing related to turbulence Accumulation of positive phase shift over the course of the scan Fat-saturation pulses as used in time-of-flight imaging Inflow of unsaturated blood into the slice after the initial 90-degree pulse Flow-related enhancement is caused by 'naive' blood entering the slice. Materials and methods Experiments were performed with a 0.2T magnet on a network of small interacting air-filled cylinders along with Magnetic resonance imaging (MRI) simulations integrating intravoxel dephasing. Signal decay over echo time was assessed at different pixel sizes on real and simulated images. The refocusing mechanism fails if intravoxel dephasing exceeds ±180º manifest by band-like artifacts. 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.

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(C) Further lowering of the encoding gradient moment (4.0 mm/π) results in significant improvement in terms of reduced signal loss in the myocardium due to intravoxel dephasing. Politics, Philosophy, Language and Communication Studies.

Shortening the MRI parameter echo time (TE) and decreasing voxel size can be used to reduce the degree of intravoxel dephasing seen on GRE acquisition. less intravoxel dephasing.
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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.

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. Intravoxel dephasing related to turbulence Accumulation of positive phase shift over the course of the scan Fat-saturation pulses as used in time-of-flight imaging Inflow of unsaturated blood into the slice after the initial 90-degree pulse Flow-related enhancement is caused by 'naive' blood entering the slice. Materials and methods Experiments were performed with a 0.2T magnet on a network of small interacting air-filled cylinders along with Magnetic resonance imaging (MRI) simulations integrating intravoxel dephasing.