Optimization of fast Quantitative Multiparameter Mapping (MPM) at 7T using parallel transmission

Synopsis

We propose a fast MPM protocol at 7T using skipped-CAIPI 3D-EPI with simple PTx water-excitation based on 3 kT-points. By comparison to corresponding CP mode scans, the 3 kT-points excitation mainly improves the B1+ field homogeneity in the Cerebellum. Using MPM B1+ field correction, this simple improvement is sufficient to achieve good and homogeneous T1, PD and T2* estimates throughout the brain. However, the lack of MT homogenization still results in the inadequate MTsat CNR. By combining MPM with EPI and PTx, we obtained quantitative whole-brain parameter maps of high quality, except for Cerebellar MTsat within 3 minutes scan time.

Summary of Main Findings

Fast MPM is achieved at 7T using 3D-EPI with PTx pulses to reduce B1+ field variation. The weighted PTx images are more homogeneous in the Cerebellum. The residual variations are corrected by B1+ map in the MPM framework, resulting in high-quality parameter maps.