Quantitative magnetization transfer imaging (qMTI) methods are able to estimate fundamental sample parameters, such as the relative size of the solid-like macromolecular proton pool and the spin exchange rate between this pool and the directly measured free water protons. One such method is selective inversion recovery (SIR), in which the free water protons are selectively inverted and the signal is fit to a biexponential function of the inversion time (TI). SIR uses only low-power pulses and requires no separate RF (B1) or static field (B0) field maps, and the analysis is largely independent of the macromolecular pool lineshape. These are all advantages over steady-state off-resonance saturation qMTI methods. However, up to now, SIR has been implemented only with repetition times TR>>T1. This paper describes a modification of SIR with smaller TR values and a greater signal-to-noise ratio (SNR) efficiency.
Copyright (c) 2007 Wiley-Liss, Inc.