QUANTIFICATION OF ERYTHROCYTE AGGREGATION BY BLOOD ECHOGENICITY - A PRELIMINARY-STUDY

Many techniques were proposed to assess erythrocyte aggregation in cli nical and experimental investigations in view of in vitro determinatio n. However no methodology until now is available to measure erythrocyt e aggregation in flowing blood in vitro. High resolution ultrasonograp hy provides an original way to quantify erythrocyte aggregation using the echogenicity of blood. We have developed and A-mode ultrasound sca nner coupled with an oscilloscope and a computer allowing the analysis of ultrasonic signals produced by erythrocytes. A closed measurement chamber connected to a calibrated roller-type blood pump where blood w as perfused was used. The echogenicity of blood was determined at diff erent shear rates. Dextran, fibrinogen and other high molecular weight substances were added to increase erythrocyte aggregation. Changes in red blood concentration was also tested. An increase in blood echogen icity rate was observed at low shear. At a given shear rate blood echo genicity increased when fibrinogen or dextran were added. Such determi nation of the echogenicity of flowing blood in vitro will provide an a pproach to the quantification of erythrocyte aggregation in vivo circu lation, especially in the veins where low shear rates are observed.