A technique of double‐resonant operation of ¹⁹F and ¹H quadrature birdcage coils

A technique was developed to change the resonant frequency of a rotating field birdcage coil from 19F resonance (76.14 MHz) to 1H resonance (80.92 MHz). This was done by inserting an additional shield with a smaller radius on the coil which resonates at 19F. It was shown that the inhomogeneity introduced by reducing the shield radius is not significant. A working coil built with this technique produced both 19F and 1H images satisfactorily.