Q-space Propagator Maps of Mouse Spinal Cord Provide Insight into Regional Axonal Architecture
Ong H, Wehrli S, Wright A, Saha P, Wehrli F, Souza A, Schwartz E
Department of Radiology, University of Pennsylvania
Q-space imaging offers potential for indirect tissue architecture quantification by exploiting regularity in porous systems. Using a custom-built 50T/m z-gradient/RF coil set, we have created high-resolution propagator maps at 0.65 micron resolution of cervical and thoracic spinal cord regions for three healthy adult mice. The calculated propagator FWHM, which is proportional to axon diameter, was assigned to each pixel location. Focusing on three WM tracts that showed characteristically different mean axon diameters (cuneatus, gracilis, and rubrospinal tract), the propagator maps showed significant differences in FWHM between each region that correlated with mean diameters as computed from histologic images.