Efficiency of Single-Loop and Quadrature Surface RF Coils in the Human Brain at 9.4 Tesla

Dinesh K. Deelchand¹, Gregor Adriany¹, Can Akgun¹, Kamil Ugurbil¹, Pierre-Gilles Henry¹, Pierre-Francois Van de Moortele¹

Single-loop and quadrature surface RF coils are often used for NMR spectroscopy since higher signal-to-noise ratio can be achieved in comparison to single channel volume coils. This study shows that single-loop coils are inefficient for human brain spectroscopy studies at 9.4 Tesla because the areas of high values in transmit and receive B₁ fields do not overlap in space. On the other hand, quadrature surface coils can still be used as long as the phase between the two coil elements is optimized for a given region-of-interest in order to increase the B₁ transmit efficiency.