Quantitative imaging of magnetization transfer exchange and relaxation properties in vivo using MRI

We describe a novel imaging technique that yields all of the observable properties of the binary spin-bath model for magnetization transfer (MT) and demonstrate this method for in vivo studies of the human head. Based on a new model of the steady-state behavior of the magnetization during a pulsed MT-weighted imaging sequence, this approach yields parametric images of the fractional size of the restricted pool, the magnetization exchange rate, the T-2 of the restricted pool, as well as the relaxation times in the free pool. Validated experimentally on agar gels and samples of uncooked beef, we demonstrate the method's application on two normal subjects and a patient with multiple sclerosis. (C) 2001 Wiley-Liss, Inc.