Pulsed saturation of the standard two-pool model for magnetization transfer. Part II: The transition to steady state

The transition of the tissue signal to steady state under periodic selective saturation of macromolecular magnetization can be observed by single-shot echo-planar imaging. The general solution for a two-pool system with linear exchange kinetics contains two transient components. The rapid minor transient causes an initial delay of the transition for fast pulse repetition (PR) and weak saturation. The slow major transient combines progressive direct saturation and transferred saturation. Its PR-dependence provides similar information as the steady state, but is less sensitive to direct saturation and fitting errors. Sampling at different PR allows to quantify all system parameters. (C) 2004 Wiley Periodicals, Inc.