In one aspect, a method for imaging fluid flow and/or perfusion using spin
labeling is provided. The method comprises applying a first magnetic
gradient sequence at least to a labeling region, applying a first pulsed
radio frequency (RF) sequence to the labeling region to label the fluid,
the first pulsed RF sequence comprising a first plurality of pulses
wherein an amplitude envelope is non-zero, the first plurality of pulses
each separated by a respective first plurality of intervals wherein the
amplitude envelope is substantially zero, and acquiring at least one
first signal emitted from an imaging region a predetermined delay after
applying the first pulsed RF sequence.