Patent ID: 8269499
Filing Date: 2012-09-18
Classification: G01R

Abstract:
1. A disconnectable MRI RF coil assembly having RF transmit functionality and which is manually connectable to an MRI system having a gantry including a static magnet, a gradient coil set and a built-in fixed RF coil assembly, said disconnectable RF coil assembly comprising: an MRI RF coil configured to electromagnetically transmit MRI RF fields to an object being imaged in the gantry of the MRI system when it is connected to the MRI system and MRI RF current is passed through said coil; RF feed circuitry configured to feed MRI RF current to said disconnectable coil from a manually operated connection interface with the MRI system; and at least one variable impedance electrically connected within or to at least one of said disconnectable RF coil and said feed circuitry, said variable impedance comprising an electrically-connected switch having at least two back-to-back serially connected diodes and being configured to change it impedance to passage of RF current between different first and second impedance states in response to said disconnectable RF coil assembly being disconnected from the MRI system, said at least one variable impedance thereby automatically protecting the disconnectable coil assembly from excessive induced RF current flow generated by transmitted MRI RF fields from the built-in fixed RF coil assembly when the disconnectable coil assembly is not connected to the MRI system.