Pseudo-random arterial modulation (PRAM): a novel arterial spin labeling approach to measure flow and blood transit times.

PURPOSE

To investigate blood flow and transit time measurement, using the pseudo-random arterial modulation (PRAM).

MATERIALS AND METHODS

PRAM is based on a pseudo-random sequence of inversions and noninversions of the arterial blood at a labeling plane inferior to the imaging plane. To accomplish this, a pseudo-continuous tagging is used to create inversion or noninversion prepulses before a gradient echo sequence and tested on phantoms and human volunteers.

RESULTS

We have shown here that the PRAM technique can measure the velocity profile and the transit time accurately and efficiently both in a phantom and in vivo in a human brain.

CONCLUSION

PRAM does not require separate control and label acquisition as is common in arterial spin labeling (ASL) but rather measures the distribution of transit times to a voxel within one integrated scan. The PRAM method is a model-free approach in measuring transit time distributions, and therefore ultimately should provide more accurate perfusion measurements.