Abstract:
A method for measuring the velocity of a fluid in a conduit, for example, blood in a blood vessel, using pulsed nuclear magnetic resonance, in which velocity is derived from measuring the mean instantaneous frequency of FID or spin echo signals. A feedback loop is used to monitor the velocity of the fluid and to generate either FID or spin echo signals depending upon the fluid velocity and/or decay of the FID signal. Radio frequency pulses are applied to suitable static axial magnetic gradients to obtain flow measurement from within a specific volume.