Diffusion MRI With High to Ultrahigh b-Values: How It Will Benefit the Discovery of Brain Microstructure and Pathological Changes

ABSTRACT

Diffusion MRI (dMRI) has been widely utilized to probe the random motion of water molecules in tissues. In a dMRI acquisition protocol, diffusion weighting or b-value is one of the most important parameters to consider. In recent years, high and ultrahigh b-values have become popular partly due to advances in hardware. In this mini-review, we will discuss impacts of high/ultrahigh b-values in three different areas: brain microstructure, tractography, and clinical applications. We will emphasize advantages of high b-value in probing diffusion within highly restricted regions or fine structures with enhanced diffusion contrast. A short summary is included at the end of each section to illustrate both advantages and disadvantages of using a high/ultrahigh b-value for each purpose.