Xiao-Hong Zhu1, Wei Chen1
1CMRR, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, United States
This study aims to exploit new MR approaches for noninvasively measuring the rotational correlation time (τ c) and hydrodynamic radius (Rh) of the brain tissue water. in vivo 17O MRS was used to measure T1 of the quadrupolar 17O spin of water in the rat brain at 9.4T, and to calculate τ c according to a simple, field-independent relation. 1H MRI was applied to image the brain translational diffusion coefficient (Dt); and the value of Rh was derived from the Dt/T1 ratio. It was found that i) the brain water τ c was in a range of several picoseconds and sensitive to brain temperature change, ii) Rh was about 1 that is in line with the water molecular size. This work indicates excellent utilities of in vivo 17O MRS for potentially imaging the microscopic matrix of brain tissue water properties in vivo.