The Efficiency Optimization of a Triple-Tuned (2H/23Na/31P) Body Coil at 7T

Motivation: Low B1+ field 1)increases the RF pulse duration which jeopardizes SNR in the short T2 of 23Na spins and 2)limits of the excitation bandwidth which might be insufficient to excite the full chemical shift dispersion of 31P spins. Goal(s): To improve the efficiency of a triple-tuned (2H/23Na/31P) body coil. Approach: Reducing the total loss on a birdcage design by decreasing the number of multi-tuned circuits. Results: The 8-rungs (i.e., 16 triple-tuned circuits) design wins 3dB in efficiency against a conventional 24-rungs (i.e., 48 double-tuned circuits) design, while covering one more excitation frequency, and the homogeneity is practically unaffected. Impact: The high loss of the multi-tuned circuits is a determinant in multi-tuned borecoil designs. Reducing the number of multi-tuned circuits used in the design substantially improves the B1 efficiency of a body coil facilitating even triple tuning.