Magnetic resonance signal detection using remotely positioned receive coils

摘要

The receive coil arrangement includes an inner coil adjacent the part to be imaged so as to maximize the received MR signal and an outer coil, which may be the built in body coil of the magnet, connected by cable to the signal processing system. Both the coils are individually tuned to the common resonant frequency and the receive coil include an arrangement to halt current flow therein during the transmit stage. The first coil has no cable and is arranged to communicate the MR signal therein to the signal processing system through the outer coil by inducing the MR signal onto the outer coil. Despite inherent losses by interfering with the tuning of the loops and in the inductive coupling this magnifies the MR signal and makes the first coil wireless. Arrangements are provided for generating from the output of the second coil separate signals for separate channels of the signal processing unit.

主权项

1. A method for MR imaging of a body of a patient comprising
operating an MR magnet with gradient coil to generate a variable magnetic field to be applied to the body of the patient; operating an RF transmit coil arrangement for generating RF pulses in a transmit stage to be applied to the body of the patient to be imaged such that the body of the patient generates an MR signal in response to the magnetic field and the RF signal applied; acquiring the MR signal in a receive stage; and processing the MR signal by which an image is generated; wherein the MR signal is acquired by: locating at least one first receive coil inside the body of the patient so as to receive the MR signal; locating at least one second receive coil outside the body of the patient adjacent said at least one first coil; communicating the RF signal in said at least one second coil by a signal communication cable connected to the signal processing system; tuning said at least one second coil and said at least one first coil to a common resonant frequency for receiving said MR signal; preventing the presence of said first and second coils from interfering with the MR signal during the transmit stage; and communicating the MR signal in said at least one first coil to the signal processing system through said at least one second coil by inducing the MR signal thereon onto said at least one second coil; wherein said at least one second receive coil is located at a spacing from said at least one first receive coil such that the signal from said at least one first receive coil is induced onto said at least one second receive coil at an efficiency of induction sufficient that the MR signal on said at least one second receive coil is greater than the MR signal which would be generated in the absence of said at least one first receive coil and mutual inductance between said at least one first receive coil and said at least one second receive coil is insufficient to change the tuned common resonant frequency of said at least one first receive coil and said at least one second receive coil sufficiently to reduce the MR signal at said at least one second receive coil to a value which is less than the MR signal which would be generated in the absence of said at least one first receive coil.