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Updated: Jun 15, 2025

Diffusion Imaging in the Rat Cervical Spinal Cord
Published on: April 7, 2015
Nonparametric distributions of tensor-valued Lorentzian diffusion spectra for model-free data inversion in
Omar Narvaez1, Maxime Yon2, Hong Jiang2
1A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
Abstract:
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- and frequency-dependent (restricted) and anisotropic self-diffusion of water. While new designs of time-dependent magnetic field gradient waveforms have enabled disambiguation between different aspects of translational motion that are convolved in traditional MRI methods relying on single pairs of field gradient pulses, data analysis for complex heterogeneous materials remains a challenge. Here, we propose and demonstrate nonparametric distributions of tensor-valued Lorentzian diffusion spectra, or "D(ω) distributions," as a general representation with sufficient flexibility to describe the MRI signal response from a wide range of model systems and biological tissues investigated with modulated gradient waveforms separating and correlating the effects of restricted and anisotropic diffusion.
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