RF coil ringing following an excitation pulse is particularly
problematic at low frequency and can prevent the measurement of signals from
short-T2 samples or tissues; this issue can be addressed by Q-switching. A
Q-switch circuit, designed to operate at 2.5 MHz and reduce the dead-time of an
RF coil following an RF pulse, is described. The resulting reduction in coil
dead-time allows signal to be detected earlier and RF pulses to be spaced
closer together. MOSFETs are used in our design to isolate RF from the DC
control system and the circuit can be inductively coupled to any RF coil. The
device was found to reduce the duration of coil ringing by a factor of five.
