MRI Edge Enhancement as a Diffusive Discord of Spin Phase Structure

Stepišnik, Janez; Duh, Andrej; Mohorič, Aleš; Serša, Igor

doi:10.1006/jmre.1998.1678

Cited by 10 publications

(11 citation statements)

References 16 publications

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“…Figure 2 (right) shows the compartment magnetization when varying δ. The well known edge effects [2][3][4][5] are noticeable already for δ = 10 −3 ∆ and increase to be extreme roughly at δ = 0.1 ∆. For longer δ the averaging effect of the diffusion effectively prevents a build up of a strong local magnetization.…”

Section: Resultsmentioning

confidence: 90%

An Iterated Complex Matrix Approach for Simulation and Analysis of Diffusion MRI Processes

Knutsson

Herberthson

Westin

2015

Lecture Notes in Computer Science

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Abstract. We present a novel approach to investigate the properties of diffusion weighted magnetic resonance imaging (dMRI). The process of restricted diffusion of spin particles in the presence of a magnetic field is simulated by an iterated complex matrix multiplication approach. The approach is based on first principles and provides a flexible, transparent and fast simulation tool. The experiments carried out reveals fundamental features of the dMRI process. A particularly interesting observation is that the induced speed of the local spatial spin angle rate of change is highly shift variant. Hence, the encoding basis functions are not the complex exponentials associated with the Fourier transform as commonly assumed. Thus, reconstructing the signal using the inverse Fourier transform leads to large compartment estimation errors, which is demonstrated in a number of 1D and 2D examples. In accordance with previous investigations the compartment size is under-estimated. More interestingly, however, we show that the estimated shape is likely to be far from the true shape using state of the art clinical MRI scanners.

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Section: Resultsmentioning

confidence: 90%

An Iterated Complex Matrix Approach for Simulation and Analysis of Diffusion MRI Processes

Knutsson

Herberthson

Westin

2015

Lecture Notes in Computer Science

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“…This has been discussed by several authors in various contexts (see, e.g., [32,33,34,35] and references therein). Exact 2D simulations are introduced here to evaluate edge enhancement effects in our imaging situations, with results given for these simulations in B.…”

Section: Exact 2d Simulationsmentioning

confidence: 89%

Achieving high spatial resolution and high SNR in low-field MRI of hyperpolarised gases with Slow Low Angle SHot

Safiullin¹,

Talbot²,

Nacher³

2013

Journal of Magnetic Resonance

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MRI of hyperpolarised gases is usually performed with fast data acquisition to achieve high spatial resolutions despite rapid diffusion-induced signal attenuation. We describe a double-cross k-space sampling scheme suitable for slow low angle shot (SLASH) acquisition and yielding an increased SNR. It consists of a series of anisotropic partial acquisitions with a reduced resolution in the read direction, which alleviates signal attenuation and still provides a high isotropic resolution. The advantages of SLASH imaging over conventional FLASH imaging are evaluated analytically, using numerical lattice calculations, and experimentally in phantom cells filled with hyperpolarised 3 He-N2 gas mixtures. Low-field MRI is performed (here 2.7 mT), a necessary condition to obtain long T * 2 values in lungs for slow acquisition. Two additional benefits of the SLASH scheme over FLASH imaging have been demonstrated: it is less sensitive to the artefacts due to concomitant gradients and it allows measuring apparent diffusion coefficients for an extended range of times.

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“…The results perfectly correspond to the calculations based on the spin phase averaging using the cumulant expansion in the Gaussian approximation. This theory gives the spin-echo signal of confined spins as (6,7,10) …”

Section: Spin-echo Distribution In a Porementioning

confidence: 99%

“…Clearly, VCF depends on the duration of the measurement as well as on the location of the jth spin subensemble. The phasing factor F aj (10) represents the average dephasing of a spin in the jth subensemble, which is, in generalized form,…”

Section: Spin-echo Distribution In a Porementioning

confidence: 99%

“…These are the propagator method (1,3,4) and the method of the cumulant expansion in the Gaussian approximation (5)(6)(7)(8). The purpose of this paper is to test these methods with the results of computer simulation of the spin-echo signal distribution in an entirely closed pore, as well as with the previously published results of simulation (9) and experiments on magnetic resonance imaging (MRI) diffusion edge enhancement (10).…”

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

Computer Simulation of the Spin-Echo Spatial Distribution in the Case of Restricted Self-Diffusion

Duh

Mohorič

Stepišnik

2001

Journal of Magnetic Resonance

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MRI Edge Enhancement as a Diffusive Discord of Spin Phase Structure

Cited by 10 publications

References 16 publications

An Iterated Complex Matrix Approach for Simulation and Analysis of Diffusion MRI Processes

An Iterated Complex Matrix Approach for Simulation and Analysis of Diffusion MRI Processes

Achieving high spatial resolution and high SNR in low-field MRI of hyperpolarised gases with Slow Low Angle SHot

Computer Simulation of the Spin-Echo Spatial Distribution in the Case of Restricted Self-Diffusion

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