Universal parallel transmit pulses for pulse-acquire based whole-brain MRSI

Motivation: Using single-channel transmit coils, the $$$B_1$$$ distribution is very inhomogenous in the brain. This leads to flipangle variations and consequently signal loss in a large portion of the brain. Using parallel transmit these variations might be mitigated. Goal(s): The goal of this work is to develop universal slab-selective homogeneuos excitation pulses for whole-brain MRSI acquisitions. Approach: Slab-selective $$$k_t$$$ points excitation have been calculated under consideration of multiple off-center frequencies. Flip angle homogeneity and excitation phase linearity was examined. Results: Resulting spectra can be quantified using single-channel optimized basis functions. Clear gray matter white matter contrast is visible in metabolic maps Impact: Universal excitation pulses, especially designed for whole-brain MRSI have been applied to pulse-acquire MRSI. Anatomical features could be found in the metabolic maps, even in the cerebellum. This might be a promising step towards reliable whole-brain MRSI.