MVP-VSASL: measuring MicroVascular Pulsatility using velocity-selective arterial spin labeling.

PURPOSE

By leveraging the small-vessel specificity of velocity-selective arterial spin labeling (VSASL), we present a novel technique for measuring cerebral MicroVascular Pulsatility named MVP-VSASL.

THEORY AND METHODS

We present a theoretical model relating the pulsatile, cerebral blood flow-driven VSASL signal to the microvascular pulsatility index ( ), a widely used metric for quantifying cardiac-dependent fluctuations. The model describes the dependence of the of VSASL signal (denoted ) on bolus duration (an adjustable VSASL sequence parameter) and provides guidance for selecting a value of that maximizes the SNR of the measurement. The model predictions were assessed in humans using data acquired with retrospectively cardiac-gated VSASL sequences over a broad range of values. In vivo measurements were also used to demonstrate the feasibility of whole-brain voxel-wise pulsatility mapping, assess intrasession repeatability of , and illustrate the potential of this method to explore an association with age.

RESULTS

The theoretical model showed excellent agreement to the empirical data in a gray matter region of interest (average value of 0.898 0.107 across six subjects). We further showed excellent intrasession repeatability of the pulsatility measurement ( , ) and the potential to characterize associations with age ( , ).

CONCLUSION

We have introduced a novel, VSASL-based cerebral microvascular pulsatility technique, which may facilitate investigation of cognitive disorders where damage to the microvasculature has been implicated.