The sensitivity of diffusion MRI to microstructural properties and experimental factors

Maryam Afzali, Tomasz Pieciak, Sharlene Newman, Eleftherios Garifallidis, Evren Özarslan, Hu Cheng, Derek K Jones
2020 Journal of Neuroscience Methods  
Diffusion MRI is a non-invasive technique to study brain microstructure. Differences in the microstructural properties of tissue, including size and anisotropy, can be represented in the signal if the appropriate method of acquisition is used. However, to depict the underlying properties, special care must be taken when designing the acquisition protocol as any changes in the procedure might impact on quantitative measurements. This work reviews the state-of-the-art methods for studying brain
more » ... crostructure using diffusion MRI and their sensitivity to microstructural differences and various experimental factors. Microstructural properties of the tissue at a micrometer scale can be linked to the diffusion signal at a millimeter-scale using modeling. In this paper, we first give an introduction to diffusion MRI and different encoding schemes. Then, signal representation-based methods and multi-compartment models are briefly explained. The sensitivity of the diffusion MRI signal to the microstructural components and the effects of curvedness of axonal trajectories on the diffusion signal are reviewed. Factors that impact on the quality (accuracy and precision) of derived metrics are then reviewed, including the impact of random noise, and variations in the acquisition parameters (i.e., number of sampled signals, b-value and number of acquisition shells). Finally, yet importantly, typical approaches to deal with experimental factors are depicted, including unbiased measures and harmonization. We conclude the work with some future directions and recommendations on this topic.
doi:10.1016/j.jneumeth.2020.108951 pmid:33017644 pmcid:PMC7762827 fatcat:oi3x6utivvh6pbqalmbg3zr5tm