Failsafe protection from induced RF current for MRI RF coil assembly having transmit functionality

摘要

An electrically-controlled failsafe switch is included in an MRI transmit-and-receive RF coil assembly so as to protect it from induced RF currents in the event it is disconnected from an MRI system, but inadvertently left linked to strong MRI RF fields during imaging procedures using other RF coils.

主权项

1. An MRI RF coil assembly having RF transmit functionality and RF receive functionality, and which is connectable to an MRI system, said RF coil assembly comprising:
an MRI RF coil configured to electromagnetically transmit MRI RF fields to an object being imaged in an MRI system gantry when MRI RF current is passed through said coil; RF feed circuitry configured to feed MRI RF current to said coil from a connection interface with an MRI system; and a variable impedance electrically connected within or to at least one of said RF coil and said feed circuitry, said variable impedance protecting the coil assembly from damage due to induced RF current flow when the coil assembly is not connected to the MRI system, wherein the variable impedance is configured so that an impedance state thereof adapts to three operational modes of: a first mode in which the RF coil assembly is not connected to the MRI system; a second mode in which the RF coil assembly is connected to the MRI system and the RF transmit functionality operates; and a third mode in which the RF coil assembly is connected to the MRI system and the RF receive functionality operates, wherein the first mode provides a high impedance causing substantial attenuation of induced RF current flow and the second and third modes provide low impedance permitting substantially unimpeded flow of MRI RF imaging currents between the RF feed circuitry and the coil.