Abstract #2637
The effect of diffusion in the extracellular space on double-PFG measurements of axon size: Insights from Monte-Carlo simulations
Gregory T Baxter 1 , Vitaly Galinsky 1 , Evren Ozarslan 2 , Peter J Basser 3 , and Lawrence R Frank 1,4
1
Center for Scientific Computation in
Imaging, Dept. of Radiology, University of California,
San Diego, CA, United States,
2
Department
of Radiology, Brigham and Women's Hospital, Harvard
Medical School, Boston, MA, United States,
3
Section
on Tissue Biophysics and Biomimetics, PPITS, NICHD,
National Institutes of Health, Bethesda, MD, United
States,
4
Center
for Functional MRI, Dept of Radiology, University of
California, San Diego, CA, United States
We present Monte-Carlo simulations of diffusion within
hexagonally packed arrays of cylinders mimicking the
white-matter, and report the signal behavior for
double-PFG experiments with zero mixing times. We
investigate the accuracy of the axonal diameter
estimates when a bi-compartmental model that assumes
Gaussian diffusion outside the cells is employed.
Despite the substantially underestimated bulk
diffusivity values, cell diameter and volume fraction
estimates are both adequately captured by such a
bi-compartmental model. Some underestimation of cell
diameters is expected only for tightly packed
configurations.
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