Using simulation to estimate probability density functions of bound water molecules with DSI

Abstract

In order to explore the physical basis by which high resolution diffusion imaging derives information about fiber alignment and diameter, we simulated a model diffusion experiment employing a random walk paradigm. A simulation of a model diffusion spectrum imaging experiment was written in Java in order to compare the diffusive behavior of particles in a perfectly reflecting channel with the internal compartment of the myofibers contained in an imaged mouse tongue. The simulated probability distribution function (PDF) for diffusion was specifically employed to estimate the myofiber diameter for the cells imaged by tissue imaging of the tongue by DSI. Our group performed a DSI experiment on a mouse tongue with a 4.7 Tesla MRI spin echo experiment in order to reconstruct a set of PDFs for the diameter, which closely correlated with the actual values for cell diameter obtained by 3D microscopic visualization through two photon microscopy of the same tissue. These results provide method for estimating myofiber diameter through the properties of the diffusion PDF obtained by whole tissue magnetic resonance imaging.