Egg white as a blood coagulation surrogate.

Egg white, a protein-containing solution, is characterized as a blood coagulation surrogate for the acoustical and thermal evaluation of therapeutic ultrasound, especially high intensity focused ultrasound (HIFU) devices. Physical properties, including coagulation temperature, frequency dependent attenuation, sound speed, viscosity, and thermal properties, were measured as a function of temperature (20-95 degrees C). Thermal coagulation and attenuation (5-12 and 1 MHz) of cow blood, pig blood, and human blood also were assessed and compared with egg white. For a 30 s thermal exposure, both egg white and blood samples (3 mm thickness) started to denature at 65 degrees C and coagulate into an elastic gel at 85 degrees C. The attenuation of egg white was found to be similar to that of the blood samples, having values of 0.23f(1.09), 1.58f(0.61), and 2.7f(0.5) dB/cm at 20, 75, and 95 degrees C, respectively. This significant attenuation increase with temperature was determined to be caused mainly by bubble cavity formation. The other temperature-dependent parameters are also similar to the reported values for blood. These properties make egg white a potentially useful bench testing tool for the safety and efficacy evaluation of therapeutic ultrasound devices.