Rapid NMR imaging of dynamic processes using the FLASH technique.

FLASH (Fast Low-Angle SHot) imaging is a new method for rapid NMR imaging which has been demonstrated to provide abdominal images without artifacts due to respiratory or peristaltic motions. The sequence typically employs 15 degrees radiofrequency excitation pulses and acquires a free induction decay signal in the form of a gradient echo. Here FLASH images are recorded in the presence of dynamic processes with time constants even smaller than the measuring time of about 2 s for an image with a 128 X 128-pixel resolution. Experiments are carried out on flow phantoms and on rabbits yielding heart images without gating of the cardiac motion.