Through-Plane Signal Loss Recovery & B1 Inhomogeneity Reduction In Vivo at 7T using Parallel Transmission

Hai Zheng¹, Tiejun Zhao², Yongxian Qian³, Tamer Ibrahim^1,3, Fernando Boada^1,3

T2*-weighted functional MRI images at ultra high field (UHF, >3T) is severely affected by through-plane signal loss and B1 inhomogeneity in areas near air/tissue interfaces in the brain. In this study, we demonstrate a parallel transmission technique to simultaneously mitigate signal loss and B1 inhomogenetiy based on the concatenation of multi-slices main magnetic field and B1+ maps during RF pulse design. Our results demonstrate that the approach is a practical means for the reduction of signal loss during in vivo T2*-weighted functional MRI at 7T.