Optimization of T2-selective binomial pulses for magnetization transfer.

Accurate rules have been established to build binomial pulses up to fifth order, for selectively saturating protons at any given T2 with minimum power deposition. Pulse performance and sensitivity to experimental defects have been evaluated; the third order is generally found to be best suited. It is shown, by combining theory and experiment performed at 0.1 T, that matching the saturation pulse to T2 of the motionally restricted pool is essential to reveal exchange with free water protons. It is emphasized that, to date, lack of magnetization transfer contrast with binomial pulses is due mainly to insufficient RF level available with most MR imaging systems, especially at high magnetic field.