Diffusion-weighted magnetic resonance imaging at ultra-high field: From ex vivo to in vivo imaging of the human brain

The main goal of this methodological thesis was to present optimised magnetic resonance imaging (MRI) sequences for ex vivo and in vivo studies in ultra-high field scanners (UHF, from 7 T and above, beyond the conventional 1.5 or even 3 T available in the clinics). The researchers mainly worked with the STEAM sequence, which overcame several of its restrictions in these scanners. It resulted in ultra-high resolution whole-brain MRI data for ex vivo studies (achieving 400 μm , or 0.4 mm, isotropic resolution), and very highly accelerated acquisition protocols for in vivo studies (up to x 54 times the current total possible acceleration). With the current feasibility of acquiring ultra-high resolution data and highly sampled multi-contrast MRI images, data-expensive signal models can be employed; but above all, the biological microstructure features in the brain can be easily more revealed from the resulted analysis.