Abstract #5226

# Influence of the size and curvedness of neural projections on the orientationally averaged diffusion MR signal

Evren Özarslan1, Cem Yolcu1, Magnus Herberthson2, Hans Knutsson1, and Carl-Fredrik Westin1,3

1Department of Biomedical Engineering, Linköping University, Linköping, Sweden, 2Department of Mathematics, Linköping University, Linköping, Sweden, 3Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States

We studied the orientationally averaged diffusion weighted MR signal for diffusion along general curves at all three temporal regimes of the traditional pulsed field gradient measurements. We found that long fibers as well as short fibers that are straight could yield the $$q^{-1}$$$decay. The absence of such a decay suggests fibers that are short and curvy. We note that the true asymptotic behavior of the signal decay is characterized by the Debye-Porod law, which suggests $$\bar{E}(q)\propto q^{-4}$$$ at very large $$q$$\$-values. This study is expected to provide insights for interpreting the diffusion-weighted images of the central nervous system.

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