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Abstract #1567

Diffusion MRI on Undulating Versus Straight Axons: Reduced Fractional Anisotropy and Increased Apparent Axonal Diameter

Hkan Hagsltt1,2, Markus Nilsson3, Henrik Hansson3, Jimmy Ltt1,3, Danielle van Westen1,2

1Center for Medical Imaging and Physiology, Lund University Hospital, Lund, Sweden; 2Department of Diagnostic Radiology, Lund University Hospital, Lund, Sweden; 3Department of Medical Radiation Physics, Lund University, Lund, Sweden

Axons in fibre tracts may be non-straight and have an undulating, approximately sinusoidal course. It is known that axonal undulations are present in the peripheral nervous system and in some parts of the central nervous system that are subjected to strain during locomotion, for instance, the optic nerve. These undulations might affect parameters estimated using diffusion MRI, such as the fractional anisotropy. Furthermore, measurements attempting to estimate the axonal sizes might be biast towards an overestimated axonal size when undulations are present.