Correlation-timing-based erythrocyte velocity measurement using CCD imagery
William J. O'Reilly, Anthony G. Hudetz · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2001
An automated correlation method is introduced to estimate erythrocyte velocity component of erythrocyte flux within the cerebral capillary network. Erythrocyte flux, defined as the number of red blood cells passing through a plane orthogonal to the axis of erythrocyte flow in a vessel per unit time, is considered to be the closest index of capillary flow. Introduced previously is the two-point cross-correlation method, a method whereby a video photometric analyzer captures the voltage produced from two electronic windows placed over a vessel of interest. In our new method, instead of using electronic windows, we use a CCD array, focused on a two- dimensional projection of the three-dimensional capillary structure. Simulations of this method yields accurate velocity measurements at a measured cell intensity of .2 standard deviations above mean noise values or cell counts fewer than 30 cells per minute for image sequences of 180 frames captured over a time interval of three seconds. We conclude that with proper reduction in the measured standard deviation of noise and by increasing the percentage of fluorscently labeled erythrocytes injected into the rat, the correlation timing method of estimating erythrocyte velocity is an accurate substitute for hand-measured velocity calculation.