Optimum Design of Dead Time of Magnetic Resonance RF Coil

After the end of the RF emission of Magnetic Resonance Imaging (MRI) system, it must wait for the residual energy of the energy storage components such as inductors and capacitors in the RF coil to decay to a certain extent before the RF receiving channel can start collecting MRI signals. Otherwise, the oscillation current formed by the energy decay process will cause interference to the MRI signal. The waiting time, which is the dead time, should be as short as possible. Shorten the disconnection time of RF switch in RF transmission channel, and the earlier the transmit coil detuning, the faster the residual energy decay; Increase the equivalent resistance of the RF coil resonant circuit, so that the RF coil is in a high damping state, the energy in the resistance can be quickly consumed, and the RF oscillation attenuation can be accelerated; Design active detuning and passive detuning RF resonant circuit, so that the resonant point frequency quickly deviates from the Larmor frequency, the RF coil enters a rapid detuning state, and the oscillation current can rapidly attenuate. The dead time can be shortened by shortening the disconnection time of the RF switch in the RF transmit channel, increasing the equivalent resistance of the RF coil resonant circuit, and using an actively detuning or passively detuning RF resonant circuit. All of the above schemes are able to shorten the dead time, but the energy release in the rapid attenuation process reduces the intensity of the MRI signal and the quality factor value of the RF coil.