Feasibility of mitral flow assessment by echo-contrast ultrasound, part I:Determination of the properties of echo-contrast agents

Data on the ultrasonic properties of commercially available contrast agents are limited by being instrument-dependent, especially with regard to their backscattering properties, The present work describes methods of measureme nts that provide instrument-independent estimations of a contrast agent's a ttenuation coefficient and integrated backscatter index and provide them as functions of its concentration. The two studied commercially available con trast agents were Albunex(R) and Levovist(R) SHU 508-A, both representative of agents in common use for echocardiography. The attenuation coefficients and integrated backscatter indices of both agents were found to be a linea r function of their concentrations, Proportionality coefficients +/- their standard deviations are provided. Actually, square root values of the avera ged backscatter indices normalized with respect to the rms of the reference signal were determined. The coefficients of proportionality were found to be: C-A = 3.11 +/- 0.1813 dB/mm; C-L = 0.07 +/- 0.005 dB/mm for attenuation coefficients of the Albunex(R) and Levovist(R) contrast agents, respective ly, and the corresponding values for backscattering were: D-A = 0.07 +/- 0. 0054; D-L = 0.02 +/- 0.0012. Being apparatus-independent, the findings of t he study are important prerequisites for the use of these echo-contrast age nts as an indicator in research for a quantitative assessment of blood flow . (C) 2000 World Federation for Ultrasound in Medicine & Biology.