Tailored B1 Mapping for Multi-Element Transmit Applications

Kay Nehrke¹, Peter Brnert¹

Accurate B₁-mapping is an essential prerequisite for multi-element transmit applications. However, in vivo B₁-mapping is still challenging with respect to scan time and mapping accuracy. Recently, a matrix approach for B₁-mapping has been proposed to avoid adverse error propagation in the limit of low flip-angles. In the present work, this concept is extended to tailor the transmit channel encoding matrix used for the mapping scan with respect to the chosen application. This approach is essentially equivalent to the transformation of the problem to an appropriate virtual coil array. The underlying theory will be briefly outlined, and basic feasibility will be evaluated on phantoms and in-vivo.