Dynamic and Quantitative Evaluation of Blood Plasma Coagulation Employing Impulsive Acoustic Radiation Force

Various disorders, such as disseminated intravascular coagulation, may increase or reduce the fibrinogen concentration in the blood with the consequence of modifying the viscoelastic properties, such as the shear modulus, µ, of the blood clots. Therefore, measuring µ for blood, or plasma, clots can become one way of determining the fibrinogen concentration. An ultrasonic system operating in pulse-echo mode (probing system) with nominal frequency of 5 MHz and another ultrasonic system based on impulsive acoustic radiation force (IARF) were used to quantify the time-changing shear modulus of a normal control plasma and of a plasma with fibrinogen lower concentration during plasma clotting. The IARF-based ultrasonic system transmitted bursts with frequency of 2.03406 MHz, 500 cycles and 1.249 Hz of pulse repetition frequency to generate an IARF on a glass sphere (3.0 mm in diameter and density of 2500 kg/m³) embedded in a plasma sample, causing a transient displacement that was monitored by a probing system. The employed ultrasonic method was able to quantify the shear modulus of normal control plasma and plasma with fibrinogen concentration of 0.8 g/L throughout the coagulation process. The results indicate that this method can be used clinically because it uses small amounts of plasma sample and has the ability to detect differences in µ as a function of fibrinogen concentrations.