Design of a Quadrature 1H/31P Coil Using Bent Dipole Antenna and Four-Channel Loop at 3T MRI

摘要

MRI using nuclei other than protons is of clinical interest due to the important role of these nuclei in cellular processes. Phosphorous-31 (^{31P), for example, plays an important role in energy metabolism. However, measurement of31P can be challenging, as the receive signal is weak compared with that of proton (1H). Consequently, it is often necessary to integrate1H elements for localizations and B₀shimming in RF coils intended for31P measurements. Good decoupling between the1H and the31P elements is therefore essential. In this paper, bent dipole antennas tuned to1H were integrated with a four channel31P loop coil array, in a manner providing strong geometric decoupling between dipoles and loops. As the physical length of a resonant dipole antenna is too long at 3T, the dipole antennas were bent around the load. The loss of31P elements due to the presence of the dipole antennas was evaluated by measuring scattering parameters and comparing the SNR of31P spectra with and without the presence of the dipole antennas. The performance of the bent dipole antenna was evaluated by simulation and sensitivity measurement. The Q-factors and the SNR of the four-loop array were reduced by less than 5% when the bent dipole antennas were introduced. The measured sensitivity of the bent dipole was higher (15%) than that of dual-tuned birdcage. The combined bent dipole and loop array is therefore a promising design for1H/31P applications at 3T.}