Rapid Mapping of the RF Field
University of Utah
A rapid method of 3D B1 mapping is presented which uses a combination of RF pulses played about orthogonal axes to create transverse magnetization with phase varying almost linearly with B1 strength over a wide range of flip angles. Previously described limitations of this technique caused by off-resonance from B0 inhomogeneity and chemical shift are overcome by making the RF excitation as rapid as possible. This phase-sensitive method has favorable SNR characteristics and may be useful for B1 mapping for B1 inhomogeneity compensation with multidimensional pulses, coil profile measurement for parallel excitation, and coil sensitivity mapping for improved parallel imaging.