A new method for measuring red blood cell aggregation using pattern recognition techniques on backscattered ultrasound Doppler signals

In order to study the important phenomenon of aggregation of red blood cell in vitro, an original ultrasound Doppler in vitro technique has been desig ned and developed in our laboratory. In the experiments held with this new technique, erythrocyte aggregation was examined by adding dextrans of diffe rent molecular weights and concentrations for a wide range of hematocrit va lues. Consequently, a large data base of backscattered ultrasound Doppler s ignals is created. In these signals, various pattern recognition methods ha ve been applied, mainly morphological and statistical ones. It results from the employed analysis that the envelope, energy and area characteristics o f the obtained backscattered signals are quite good indicators of the degre e of RBCs aggregation. In this way, we have been able to: (a) Establish a q uantitative relation between the presence of various dextrans and the degre e of aggregation. (b) Determine the distribution of the size of the formed aggregates in the various experimental solutions. (c) Obtain a most accurat e relation between ultrasound backscattering and actual size of the corresp onding observed aggregates.