Exploration of a low-SAR ihMT-RAGE approach for human whole brain imaging at 7T

Motivation: Inhomogeneous Magnetization Transfer (ihMT) is a recent MRI technique that has raised great interest for myelin imaging. Several ihMT protocols have been proposed for whole brain imaging at clinical field strengths. However, ultra-high field (UHF, 7T) translation remains challenging. Goal(s): ln this work we explore ways to perform ihMT at UHF for clinical applications. Approach: A low-SAR ihMT-RAGE sequence is proposed by shortening the ihMT preparation and enabling partial Fourier MT saturation. Results: This original sequence addresses SAR limitations within relatively short scan times, allowing for whole brain 1.2mm isotropic resolution (resp. 1mm) in 12 minutes (resp. 16 min) at 7T. Impact: Ultra-high field ihMT enables high resolution (1mm iso) myelin specific imaging, opening new perspectives for neuroscience and clinical research. Future developments, such as reduced FOV and compressed sensing sequences could bring scan times further down to 5-10 minutes.