Multi-coil Composite Pulses for Whole-Brain Homogeneity Improved over RF Shimming Alone
Collins C, Smith M, Vaughan J, Wang Z, Mao W, Fang J, Liu W, Adriany G, Ugurbil K
Penn State College of Medicine
In recent years a number of methods for improving image homogeneity in high field MRI have been proposed, some of them relying on separate control of RF coils in a transmit array. Here we combine accurate RF field calculations with accurate representations of the Bloch equation to demonstrate that by using multiple individually-optimized pulses, more homogeneous distributions in available signal intensity over the entire brain volume can be achieved at 300 MHz than when using a single optimized (or RF shimmed) pulse with the same transmit array.