US 11,668,775 B2
Integrated active detuning for magnetic resonance imaging
Ian Robert Oliphant Connell, Toronto (CA)
Assigned to Synaptive Medical Inc., Toronto (CA)
Filed by Synaptive Medical Inc., Toronto (CA)
Filed on Jun. 29, 2021, as Appl. No. 17/362,005.
Application 17/362,005 is a continuation of application No. 16/419,098, filed on May 22, 2019, granted, now 11,073,581.
Prior Publication US 2021/0325490 A1, Oct. 21, 2021
Int. Cl. G01R 33/36 (2006.01); G01R 33/34 (2006.01)
CPC G01R 33/3621 (2013.01) [G01R 33/34076 (2013.01); G01R 33/3614 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A coil assembly for performing magnetic resonance (MR) imaging of a subject immersed in a main magnet, comprising:
a radio frequency (RF) coil shaped and sized to cover at least a portion of the subject immersed in the main magnet,
wherein the RF coil includes multiple legs, each with a characteristic impedance, and
where each leg is connected to a cable choke with a characteristic impedance smaller than the characteristic impedance of the leg connected thereto;
a quarter-wave transformer coupled to the RF coil and configured to transform a characteristic impedance of the RF coil to match an impedance of a power amplifier that drives the RF coil; and
a diode placed behind the quarter-wave transformer and away from the RF coil, wherein:
when the diode is forward biased, the diode turns the quarter-wave transformer into an open circuit such that the power amplifier provides sufficient electrical power via at least one cable choke for the RF coil to transmit an RF pulse into the portion of the subject; and
(ii) when the diode is provided zero or reverse bias, the diode turns the quarter-wave transformer into a short circuit in parallel with the at least one cable choke such that the RF coil is detuned from a Lamor frequency of nuclei from the portion of the subject immersed in the main magnet.