Magnetic resonance imaging (MRI) coil with pin diode decoupling circuit

A circuit for actively decoupling or passively decoupling a radio frequency (RF) coil used in a magnetic resonance imaging (MRI) system, the RF coil comprising at least one series capacitor, the circuit comprising:

• a pair of fast switching PIN diodes comprising a first fast switching PIN diode connected antiparallel with a second, different fast switching PIN diode, where the first fast switching diode has a carrier life time of 100 ns or less, and where the second fast switching diode has a carrier life time of 100 ns or less;
• a first DC blocking capacitor, where the first blocking capacitor is connected in series with the second fast switching PIN diode, or where the first DC blocking capacitor is connected in parallel with the second fast switching PIN diode;
• and
• a decoupling inductor connected in series with the first DC blocking capacitor and the pair of fast switching PIN diodes, where the circuit is connected in parallel with the at least one series capacitor, where the circuit actively decouples the RF coil upon injection of a DC bias into the circuit, and where the circuit passively decouples the RF coil upon generation of an induced voltage in the circuit.

A magnetic resonance imaging (MRI) apparatus comprising:

• a controller;
• a radio frequency (RF) coil operably connected to the controller, where the RF coil comprises an LC circuit comprising at least one series capacitor, where the RF coil participates in the acquisition of MR data by transmitting RF signals into an examination subject or by receiving MR signals from the examination subject, where the controller provides the RF coil with a current, a voltage, or a control signal that causes the RF coil to resonate at a desired transmission frequency;
• and
• a decoupling circuit connected in parallel to the RF coil, where the decoupling circuit actively decouples, upon injection of a DC bias into the decoupling circuit, or passively decouples, upon generation of an induced voltage in the decoupling circuit, the RF coil from one or more other RF coils associated with the MRI apparatus,
• where the decoupling circuit comprises one or more conductors, a pair of PIN diodes, at least one capacitor, and an inductor,
• where the pair of PIN diodes includes a first fast-switching PIN diode connected antiparallel to a second fast-switching PIN diode,
• where the at least one capacitor is a DC blocking capacitor connected in series or connected in parallel with the second fast-switching PIN diode, and
• where the inductor is connected in series with the at least one capacitor and the pair of PIN diodes.

A magnetic resonance imaging (MRI) radio frequency (RF) transmit/receive coil comprising:

• a receive element;
• a transmit element operably connected to the receive element;
• and
• a decoupling circuit operably connected to the transmit element or the receive element, where the decoupling circuit actively decouples the transmit element from the receive element upon injection of a DC bias into the decoupling circuit, where the decoupling circuit passively decouples the receive element from the transmit element upon the production of an induced voltage in the decoupling circuit, the decoupling circuit comprising:
• a first fast switching PIN diode connected antiparallel with a second fast switching PIN diode;
• and
• at least one DC blocking capacitor connected in series or connected in parallel with the second fast switching PIN diode.