Abstract:
Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety of phase cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and undesired signals are canceled.
Abstract:
A multicoil NMR detection and imaging apparatus allows multicoil NMR detection and imaging to be performed efficiently at low operating frequencies. The apparatus comprises an AC voltage generator, a transmit switching circuit, a coil switching network, an array of two or more detection coils, a set of receive switching circuits with one switching circuit for each detection coil, and a set of preamplifier circuits with input impedance substantially greater than the impedance of each respective detection coil at the intended operating frequency. The AC generator produces an alternating current waveform that is routed through one of more detection coils during transmit mode while the preamplifier circuits are isolated from the detection coil(s). During receive mode the AC generator is isolated from the detection coils to prevent noise from the transmitter from degrading the quality of received signals.