Dual-channel transmit-SENSE for flip-angle homogenization in the human brain at 7 Tesla: a feasibility study

Introduction: Transmit-SENSE gives the opportunity to implement short excitation pulses with good flip-anglehomogeneity [1]. Commonly, a transmitarray system used for brain imaging at 7 Tesla consists of 8 independently modulated amplifiers in combination with a dedicated 8-channel RF coil. Due to the additional degrees of freedom introduced by the separate transmit-channels, uniform excitation can be achieved with short excitation pulses. On the other hand, including additional transmit-channels is not only financially demanding, it also complicates B1-mapping and optimized pulse design. Considering the basis set of orthogonal birdcage coil modes, inclusion of the anti-circularly-polarized modes only marginally improve transmit-SENSE applications [2]. In this work we explore the possibility to drive an 8-element transmit coil with only 2 independent transmit-channels, while retaining the ability to perform adequate flip-angle(FA) homogenization in the human brain at 7 Tesla.