Assessment of Mean Apparent Propagator-based indices as biomarkers of axonal remodeling after stroke

Recently, a robust mathematical formulation has been introduced for the closed-form analytical reconstruction of the signal and the %Ensemble Average Propagator (EAP) Mean Apparent Propagator (MAP) in diffusion MRI. This is referred to as MAP-MRI or 3D-SHORE depending on the chosen reference frame. % that is Cartesian in the first case and polar in the second. From the MAP, microstructural properties can be inferred by the derivation of indices that under certain circumstances allow the estimation of of pores' geometry and local diffusivity, holding the potential of becoming the next generation of microstructural numerical biomarkers.In this work, we propose the assessment and validation of a subset of such indices that is %Return to Axis Probability (RTAP), axon diameter (D) and Propagator Anisotropy (PA) RTAP, D, and PA for the quantitative analysis of axonal remodeling in the uninjured motor network after stroke. Diffusion Spectrum Imaging (DSI) was performed on %a cohort of 20 subjects (ten patients and ten controls at different time points and the indices were derived and exploited for tract-based quantitative analysis. Our results provide quantitative evidence on the eligibility of the derived indices as microstructural biomarkers.