Design and construction of a novel ¹H/¹⁹F double-tuned coil system using PIN-diode switches at 9.4T

A double-tuned ¹H/¹⁹F coil using PIN-diode switches was developed and its performance evaluated. The is a key difference from the previous developments being that this design used a PIN-diode switch in series with an additionally inserted inductor in parallel to one of the capacitors on the loop. The probe was adjusted to ¹⁹F when the reverse bias voltage was applied (PIN-diode OFF), whilst it was switched to ¹H when forward current was flowing (PIN-diode ON). S-parameters and Q-factors of single- and double-tuned coils were examined and compared with/without a phantom on the bench. Imaging experiments were carried out on a 9.4T preclinical scanner. All coils were tuned at resonance frequencies and matched well. It is shown that the Q-ratio and SNR of double-tuned coil at ¹⁹F frequency are nearly as good as those of a single-tuned coil. Since the operating frequency was tuned to ¹⁹F when the PIN-diodes were turned off, losses due to PIN-diodes were substantially lower resulting in the provision of excellent image quality of X-nuclei.