The vast majority of High Angular Resolution Diffusion Imaging (HARDI) modeling methods recover networks of neuronal fibres, using a heuristic extraction of their local orientation. In this paper, we present a method for computing the apparent intravoxel Fibre Population Dispersion (FPD), which conveys the manner in which distinct fibre populations are partitioned within the same voxel. We prov...

Introduction. High Angular Resolution Diffusion Imaging (HARDI) has been proposed to avoid the limitations of the conventional Diffusion Tensor Imaging (DTI) and to better explore white matter micro-structure non-invasively. However, HARDI methods normally require many more samples than DTI. For example, Diffusion Spectrum Imaging (DSI), estimates the diffusion Ensemble Average Propagator (EAP)...

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Stimulated echo acquisition mode (STEAM) diffusion MRI can be advantageous over pulsed-gradient spin-echo (PGSE) for diffusion times that are long compared with T2 . It therefore has potential for biomedical diffusion imaging applications at 7T and above where T2 is short. However, gradient pulses other than the diffusion gradients in the STEAM sequence contribute much greater diffusion weighti...

High angular resolution diffusion imaging (HARDI) permits the computation of water molecule displacement probabilities over a sphere of possible displacement directions. This probability is often referred to as the orientation distribution function (ODF). In this paper we present a novel model for the diffusion ODF namely, a mixture of von Mises-Fisher (vMF) distributions. Our model is compact ...

We present a framework to build a High Angular Resolution Diffusion Image (HARDI) Atlas based on a population of HARDIs from different subjects. The method relies on a non-linear group-wise registration algorithm as well as a set of tools to re-orient the gradient directions of individual subjects and re-interpolate their diffusion weighted signal in a canonical gradient direction set in atlas ...

The insula is a complex structure involved in a wide range of functions. Tracing studies on nonhuman primates reveal a wide array of cortical connections in the frontal (orbitofrontal and prefrontal cortices, cingulate areas and supplementary motor area), parietal (primary and secondary somatosensory cortices) and temporal (temporal pole, auditory, prorhinal and entorhinal cortices) lobes. Howe...

Introduction Diffusion Tensor Imaging (DTI) provides access to fibre pathways and structural integrity in white matter and is an expanding area of the research. It finds important clinical applications in managing neurodegenerative diseases such as Alzheimer’s disease or multiple sclerosis. Many advanced techniques have been recently suggested for the reconstruction of the diffusion orientation...