Diffusion MRI at 25: Exploring brain tissue structure and function

From Diffusion MRI to Brain

Multi-Spherical Diffusion MRI: Exploring Diffusion Time Using Signal Sparsity

Effective representation of the diffusion signal’s dependence on diffusion time is a sought-after, yet still unsolved, challenge in diffusion MRI (dMRI). We propose a functional basis approach that is specifically designed to represent the dMRI signal in this four-dimensional space – varying over gradient strength, direction and diffusion time. In particular, we provide regularization tools imp...

Diffusion MRI of Brain Connectivity and Microstructure:

What is a “diffusion coefficient” or “diffusion tensor” in living tissue, anyway? While the measurement of the self-diffusivity in an NMR tube represents a "gold standard", in complex media particularly in living tissue, water “diffusivity” ceases to have a clear meaning or definition. The apparent diffusion coefficient (ADC) and apparent diffusion tensor (ADT) concepts were introduced to answe...

Brain Structure and Function

Abstract: The role of spinal dorsal horn propriospinal connections in nociceptive processing is not yet established. Recently described, rostrocaudally oriented axon collaterals of lamina I projection and local-circuit neurons (PNs and LCNs) running in the dorsolateral funiculus (DLF) may serve as the anatomical substrate for intersegmental processing. Putative targets of these axons include la...

Director Field Analysis (DFA): Exploring Local White Matter Geometric Structure in Diffusion MRI

In Diffusion Tensor Imaging (DTI) or High Angular Resolution Diffusion Imaging (HARDI), a tensor field or a spherical function field (e.g., an orientation distribution function field), can be estimated from measured diffusion weighted images. In this paper, inspired by the microscopic theoretical treatment of phases in liquid crystals, we introduce a novel mathematical framework, called Directo...