Built-in coil current sensing for 1H/23NA MRI

A current sensing system for a multi-tuned magnetic resonance imaging (MRI) scanner, comprising:

• a coil network of a multi-tuned radiofrequency (RF) coil, comprising:
• up to two parallel transmission lines connected to a transmission antenna of the multi-tuned radiofrequency (RF) coil, wherein each of the up to two parallel transmission lines have a length of quarter-wavelength;
• and
• 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;
• a transmission line segment, comprising:
• a first transmission line having a length selected from a multiple of half-wavelength and a multiple of double quarter-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 in combination with 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 at least one of a 1H resonant frequency and a 23Na 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 1H resonant frequency and the 23Na resonant frequency;
• and
• wherein the current sensing system tuned to at least one of the 1H resonant frequency and the 23Na resonant frequency one or more resonant frequencies is configured to sense a current of the multi-tuned radiofrequency (RF) coil at a respective tuned resonant frequency by sensing a voltage of the matching network coupled to the power amplifier.

A method for sensing current of a radiofrequency (RF) coil of a dual-tuned magnetic resonance imaging (MRI) scanner, comprising:

• connecting a coil network comprising up to two parallel transmission lines, each with a length of a quarter-wavelength to a transmission antenna of the radiofrequency (RF) coil;
• connecting a matching network comprising a transmission line with a length of a quarter-wavelength to a power amplifier of the magnetic resonance imaging (MRI) scanner;
• connecting the matching network and the coil network using a transmission line segment with a length of at least one of a multiple of half-wavelength and a multiple of double quarter-wavelength;
• tuning the coil network, the matching network, and the transmission line segment to a first resonant frequency of the dual-tuned magnetic resonance imaging (MRI) scanner;
• tuning the coil network, the matching network, and the transmission line segment to a second resonant frequency of the dual-tuned magnetic resonance imaging (MRI) scanner using three pairs of shunt capacitors with each pair of shunt capacitors connected across each of the coil network, the matching network, and the transmission line segment;
• setting the coil network, the matching network, and the transmission line segment to at least one of the first resonant frequency and the second resonant frequency of the dual-tuned magnetic resonance imaging (MRI) scanner using six PIN diodes, wherein each of the six PIN diodes is connected in series to each of the shunt capacitor of the three pairs of shunt capacitors;
• and
• sensing a current of the radiofrequency (RF) coil of the dual-tuned magnetic resonance imaging (MRI) scanner tuned to at least one of the first resonant frequency or the second resonant frequency by measuring a voltage across the matching network connected to the power amplifier,
• wherein at least one of the first resonant frequency and the second resonant frequency is a 23Na resonant frequency.