A practical double‐tuned 1 H/ 31 P quadrature birdcage headcoil optimized for 31 P operation

A double‐tuned 1 H/ 31 P birdcage head coil for use with humans at 1.5 T is described. The coil was designed for proton‐decoupled 31 P excitation and reception and incorporated a number of practical features including optimized sensitivity for 31 P, quadrature operation at 1 H and 31 P frequencies, and a radiofrequency (RF) mirror for improved B 1 homogeneity. The design achieved similar B 1 homogeneity at both 31 P and 1 H frequencies. Inductive matching was used to accommodate samples with large loading differences. A facile method for tuning and matching over a variety of sample loadings is presented, along with capacitively shortened bazookas for suppression of cable braid currents. The proton sensitivity, although down by approximately a factor of two compared with an optimized 1 H birdcage head coil, was still ample for shimming and generation of scout images. Advantages of the design are discussed and proton‐decoupled 31 P spectra of human brain are presented. Magn Reson Med 42:173–182, 1999. © 1999 Wiley‐Liss, Inc.