Probing axons using multi-compartmental diffusion in multiple sclerosis
In: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6764633/
Objects The diffusion-based spherical mean technique (SMT) provides a novel model to relate multi-b-value diffusion magnetic resonance imaging (MRI) data to features of tissue microstructure. We propose the first clinical application of SMT to image the brain of patients with multiple sclerosis (MS) and investigate clinical feasibility and translation. Methods Eighteen MS patients and nine age- and sex-matched healthy controls (HCs) underwent a 3.0 Tesla scan inclusive of clinical sequences and SMT images (isotropic resolution of 2 mm). Axial diffusivity (AD), apparent axonal volume fraction (V-ax), and effective neural diffusivity (D-ax) parametric maps were fitted. Differences in AD, V-ax, and D-ax between anatomically matched regions reflecting different tissues types were estimated using generalized linear mixed models for binary outcomes. Results Differences were seen in all SMT-derived parameters between chronic black holes (cBHs) and T2-lesions (P <= 0.0016), in V-ax and AD between T2-lesions and normal appearing white matter (NAWM) (P < 0.0001), but not between the NAWM and normal WM in HCs. Inverse correlations were seen between V-ax and AD in cBHs (r = -0.750, P = 0.02); in T2-lesions D-ax values were associated with V-ax (r = 0.824, P < 0.0001) and AD (r = 0.570, P = 0.014). Interpretations SMT-derived metrics are sensitive to pathological changes and hold potential for clinical application in MS patients. ; Sources of support include: extramural program of the National Institutes of Health (NIH) (NIBIB K01 EB009120, R01 EB000461, and K25 EB013659), the Clinical and Translational Science Awards (UL1TR000445-06 from National Center for Advancing Translational Sciences/NIH), the European Union Horizon 2020 (EU H2020 634541-2), the EPSRC (Engineering and Physical Sciences Research Council), United Kingdom (UK) (UK EPSRC EP/M020533/1, UK EPSRC EP/N018702/1), the National MS Society (MS Clinical Mentorship Program, NMSS PP-180129686 and NMSS RG-1501-02840).