Mri current sensing system

A balun-balanced MRI current sensing system, comprising:

• a coil network of a dual-tuned radiofrequency (RF) coil, comprising:
• up to two parallel transmission lines connected to a transmission antenna of the dual-tuned radiofrequency (RF) coil, wherein each of the up to two parallel transmission lines has a length of quarter-wavelength;
• a pair of first shunt capacitors connected across the up to two parallel transmission lines, wherein each first shunt capacitor of the pair of first shunt capacitors is connected in series with a respective PIN diode;
• and
• a pair of baluns connected across the up to two parallel transmission lines;
• a transmission line segment, comprising:
• a first transmission line having a length of a multiple of half-wavelength;
• and
• a pair of second shunt capacitors connected across the first transmission line, wherein each second shunt capacitor of the pair of second shunt capacitors is connected in series with a respective PIN diode;
• a matching network coupled to a power amplifier, comprising:
• a second transmission line having a length of a quarter-wavelength;
• and
• a pair of third shunt capacitors connected across the second transmission line, wherein each third shunt capacitor of the pair of third shunt capacitors is connected in series with a respective PIN diode;
• wherein the respective length of the first transmission line and the second transmission line are configured to tune the current sensing system to a fundamental frequency and to a first odd multiple frequency of the fundamental frequency, wherein the fundamental frequency is a 31P resonant frequency;
• wherein each of the pair of first shunt capacitors, the pair of second shunt capacitors and the pair of third shunt capacitors are configured to tune the current sensing system to a 1H resonant frequency;
• wherein each of the respective PIN diodes of the pair of first shunt capacitors, the pair of second shunt capacitors and the pair of third shunt capacitors are configured to set the current sensing system to at least one of the 31P resonant frequency and the 1H resonant frequency;
• and
• wherein the current sensing system is tuned to at least one of the 31P resonant frequency and the 1H resonant frequency, and is configured to sense a current of the dual-tuned radiofrequency (RF) coil network at a respective tuned resonant frequency by sensing a voltage of the matching network coupled to the power amplifier.