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Related papers: Mapping axonal density and average diameter using …

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We enable the estimation of the per-axon axial diffusivity from single encoding, strongly diffusion-weighted, pulsed gradient spin echo data. Additionally, we improve the estimation of the per-axon radial diffusivity compared to estimates…

Medical Physics · Physics 2022-07-07 Marco Pizzolato , Erick Jorge Canales-Rodríguez , Mariam Andersson , Tim B. Dyrby

Variable kernel density estimation allows the approximation of a probability density by the mean of differently stretched and rotated kernels centered at given sampling points $y_n\in\mathbb{R}^d,\ n=1,\dots,N$. Up to now, the choice of the…

Statistics Theory · Mathematics 2018-05-07 Ilja Klebanov

Axon diameter and myelin thickness affect the conduction velocity of action potentials in the nervous system. Imaging them non-invasively with MRI-based methods is thus valuable for studying brain microstructure and function. Electron…

Axonal damage is the primary pathological correlate of long-term impairment in multiple sclerosis (MS). Previous work has demonstrated a strong, quantitative relationship between decrease in axial diffusivity and axonal damage. In the…

Computational Engineering, Finance, and Science · Computer Science 2024-10-15 Nand Sharma

To study axonal microstructure with diffusion MRI, axons are typically modeled as straight impermeable cylinders, whereby the transverse diffusion MRI signal can be made sensitive to the cylinder's inner diameter. However, the shape of a…

Medical Physics · Physics 2020-08-18 Hong-Hsi Lee , Sune N. Jespersen , Els Fieremans , Dmitry S. Novikov

Magnetic resonance imaging (MRI) is the method of choice for noninvasive studies of micrometer-scale structures in biological tissues via their effects on the time/frequency-dependent ("restricted") and anisotropic self-diffusion of water.…

Soft Condensed Matter · Physics 2021-11-16 Omar Narvaez , Maxime Yon , Hong Jiang , Diana Bernin , Eva Forssell-Aronsson , Alejandra Sierra , Daniel Topgaard

We introduce and demonstrate a new paradigm for quantitative parameter mapping in MRI. Parameter mapping techniques, such as diffusion MRI and quantitative MRI, have the potential to robustly and repeatably measure biologically-relevant…

Image and Video Processing · Electrical Eng. & Systems 2024-11-19 Moucheng Xu , Yukun Zhou , Tobias Goodwin-Allcock , Kimia Firoozabadi , Joseph Jacob , Daniel C. Alexander , Paddy J. Slator

Mapping tissue microstructure accurately and noninvasively is one of the frontiers of biomedical imaging. Diffusion Magnetic Resonance Imaging (MRI) is at the forefront of such efforts, as it is capable of reporting on microscopic…

Medical Physics · Physics 2019-03-26 Noam Shemesh

Quantitative Magnetic Resonance Imaging (MRI) is based on a two-steps approach: estimation of the magnetic moments distribution inside the body, followed by a voxel-by-voxel quantification of the human tissue properties. This splitting…

This study aims to validate if MRI can measure anisotropic mesoscopic Larmor frequency shifts from white matter axonal microstructure relative to the B0 direction and if dMRI can estimate this anisotropy. Recent models describe how…

Medical Physics · Physics 2024-12-19 Anders Dyhr Sandgaard , Sune Nørhøj Jespersen

Diffusion magnetic resonance imaging (dMRI) is a relatively modern technique used to study tissue microstructure in a non-invasive way. Non-Gaussian diffusion representation is related to the restricted diffusion and can provide information…

Signal Processing · Electrical Eng. & Systems 2020-09-17 Tomasz Pieciak , Maryam Afzali , Fabian Bogusz , Aja-Fernández , Derek K. Jones

Objectives: Magnetic resonance elastography (MRE) is a noninvasive technique for assessing the viscoelastic properties of soft biological tissues in vivo, with potential relevance for pediatric tumor evaluation. This study aimed to evaluate…

The problem of determining a current density confined to a volume from measurements of the magnetic field it produces exterior to that volume is known to have non-unique solutions. To uniquely determine the current density, or the…

Medical Physics · Physics 2014-07-03 Daniel J. Sheltraw

Oscillating-gradient spin-echo diffusion-weighted magnetic resonance imaging (OGSE-DWI) has been promoted as a promising technique for studying the microstructure of complex hydrated matter in the frequency domain. The target of the…

Medical Physics · Physics 2023-09-15 Jeff Kershaw , Takayuki Obata

Performing k-space variable density sampling is a popular way of reducing scanning time in Magnetic Resonance Imaging (MRI). Unfortunately, given a sampling trajectory, it is not clear how to traverse it using gradient waveforms. In this…

Optimization and Control · Mathematics 2015-02-25 Nicolas Chauffert , Pierre Weiss , Marianne Boucher , Sébastien Mériaux , Philippe CIUCIU

A nonparametric kernel density estimator for directional-linear data is introduced. The proposal is based on a product kernel accounting for the different nature of both (directional and linear) components of the random vector. Expressions…

Masked autoencoders (MAE) have shown great promise in medical image classification. However, the random masking strategy employed by traditional MAEs may overlook critical areas in medical images, where even subtle changes can indicate…

Computer Vision and Pattern Recognition · Computer Science 2026-05-27 Joao Batista Florindo , Viviane de Moura

In this paper we propose methods for inference of the geometric features of a multivariate density. Our approach uses multiscale tests for the monotonicity of the density at arbitrary points in arbitrary directions. In particular, a…

Statistics Theory · Mathematics 2016-04-18 Konstantin Eckle , Nicolai Bissantz , Holger Dette , Katharina Proksch , Sabrina Einecke

In radial fast spin-echo MRI, a set of overlapping spokes with an inconsistent T2 weighting is acquired, which results in an averaged image contrast when employing conventional image reconstruction techniques. This work demonstrates that…

Medical Physics · Physics 2016-03-02 Kai Tobias Block , Martin Uecker , Jens Frahm

Diffusion magnetic resonance imaging is an imaging technology designed to probe anatomical architectures of biological samples in an in vivo and non-invasive manner through measuring water diffusion. The contribution of this paper is…

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