Range/velocity limitations for time-domain blood velocity estimation.

The traditional range/velocity limitation for blood velocity estimation systems using ultrasound is elucidated. It is stated that the equation is a property of the estimator used, not the actual physical measurement situation, as higher velocities can be estimated by the time domain cross-correlation approach. It is demonstrated that the time domain technique under certain measurement conditions will yield unsatisfactory results, when trying to estimate high velocities. Various methods to avoid these artifacts using temporal and spatial clustering techniques are suggested. The improvement in probability of correct detection is derived, and several examples of simulations are shown.