Abstract #2632

Inferring Axon Diameter Sizes using Monte Carlo Simulations and Oscillating Gradient Spin Echo Sequences

Sheryl L Herrera ¹ , Trevor J Vincent ^2,3 , Morgan E Mercredi ¹ , Richard Buist ⁴ , Christopher P Bidinosti ^1,2 , and Melanie Martin ^2,5

¹ Physics & Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada, ² Physics, University of Winnipeg, Manitoba, Canada, ³ Astronomy & Astrophysics, University of Toronto, Ontario, Canada, ⁴ Radiology, University of Manitoba, Manitoba, Canada, ⁵ Physics & Astronomy, Radiology, University of Manitoba, Manitoba, Canada

We simulate cylindrical geometries using OGSE and AxCaliber to determine diameter distributions. The fit results agree reasonably with the geometry. Numbers of small axons are underestimated and larger axons are overestimated. The calculated mean radius (1.57 plus-or-minus sign

0.01m) is comparable with the actual mean radius (1.67m). The CHARMED model simulates the extracellular space as hindered, whereas ours was restricted. Because the CHARMED model signal is proportional to r ² , the larger axons are overestimated. With noise the smaller axons are harder to identify. These reasons could account for some discrepancy between the fitted and actual data. Modifications are necessary to the CHARMED model.

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