Precision velocimetry with digital cross-correlation for flow measurements during thrombus growth.

A precise velocimetry with good frequency response is an indispensable prerequisite to studying hemodynamic effects. The need to monitor minute changes of velocity prompted the development of a software-driven velocimeter that uses a laboratory computer without implementation of specialized arithmetic hardware. Without an on-line output, this setup offers high precision (6000 time shifts), extension of the measuring range to lower velocities by nearly two orders of magnitude, an excellent temporal resolution, and resistance to bad signal-to-noise ratios. The system is described and its characteristic parameters are demonstrated. Velocimetry was performed during experiments on thrombogenesis with and without pretreatment with antithrombotic agents and was found to be valuable in assessing thrombus growth and thrombus stability in vivo.