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Abstract #0710

Large axon diffusion MRI modelling in the sciatic nerve in vivo

Ratthaporn Boonsuth1,2, Francesco Grussu1,3, Anestis Passalis1, Marco Battiston1, Claudia A. M. Gandini Wheeler-Kingshott1,4,5, and Marios C. Yiannakas1
1NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, 2Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand, 3Radiomics Group, Vall d’Hebron Institute of Oncology, Vall d’Hebron Barcelona Hospital Campus, Barcelona, Spain, 4Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy, 5Digital Neuroscience Centre, IRCCS Mondino Foundation, Pavia, Italy

Synopsis

Keywords: Diffusion Modeling, Diffusion Modeling, Peripheral Nervous System (PNS), Intra-axonal fraction, Diffusion-weighted MRI

Motivation: The “stick”, a standard zero-radius diffusion model, can bias intra-axonal fraction (fa) estimation when large axons (e.g., radii ≥ 4 µm) are present, as in the peripheral nervous system (PNS).

Goal(s): To compare signal models for in vivo fa characterization in the PNS: Ball-and-Stick (BS), Two-Axon Population (TAP) and general Gamma Distribution Axon Population (GDAP).

Approach: Maps of fa and other diffusion properties were compared in healthy and diseased (Multiple Sclerosis) sciatic nerves in vivo through BS, TAP and GDAP.

Results: TAP and GDAP models provided higher estimates of fa than BS and may thus offer promising new PNS biomarkers.

Impact: We demonstrate that diffusion MRI can accurately resolve axon diameter information in the sciatic nerve in vivo using Two-Axon Population (TAP) and Gamma Distribution Axon Population (GDAP) imaging. These methods provide higher intra-axonal signal fraction estimates than the Ball-and-Stick model

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Keywords