John T. Spear1,
2, Zhongliang Zu2, 3, John C. Gore, 3
1Department
of Physics and Astronomy, Vanderbilt University, Nashville, TN, United
States; 2Vanderbilt University Institute of Imaging Science,
Nashville, TN, United States; 3Department of Radiology, Vanderbilt
University, Nashville, TN, United States
A new method is reported for quantifying the spatial scales of susceptibility variations based on the effect of diffusion through internal gradients on the spin-lattice relaxation rate in the rotating frame R1rho (=1/T1rho). Model systems with internal field gradients exhibited significant dispersions in R1rho and fastidious analysis of these dispersions revealed three important locking fields. Three images were subsequently taken at these locking fields and combined in a novel image subtraction technique to delineate the average spatial frequency of magnetic inhomogeneities. This technique has the potential to quantitatively characterize magnetically inhomogeneous regions of tissue such as microvasculature in vivo.