Axonal Diameter Mapping using High Performance Gradients: Feasibility study and Repeatability of Estimates

High performance gradients allow for the exploration of an expanded diffusion parameter space, that simplifies biophysical model at ultra-high b=7-30 ms/μm2. The choice of b-encoding space can suppress contributions from extra-axonal water signal while utilization of high performance gradient systems allows for maintaining short echo times (TE<63 ms) with adequate SNR. In this study, the feasibility and reproducibility of mapping effective axonal diameter distributions in the in-vivo brain was assessed by making use of a test-retest paradigm. Whole brain white-matter and parcel based reproducibility and sensitivity were evaluated for this promising biomarker.