Quantification of ultrasound contrast agent in an in vitro perfusion phantom

Contrast agents improve the diagnostic capability of ultrasonic imaging. Optimized methods for agent administration and quantification of signal enhancement, however, remain under development. The authors' purpose was to develop an in vitro perfusion phantom in order to compare quantification methods. The acoustic response of contrast agent was measured simultaneously with a reference method (radio frequency RF signal analysis) and techniques more readily available in the clinic (continuous wave CW Doppler, B-mode and power Doppler cineloops). Quantitative parameters (RF integrated backscatter and attenuation; CW Doppler, B-mode and power Doppler intensity) were compared as a function of time after injection of EchoGen(R) or SonoVue/sup TM/. A good correlation was found between integrated backscatter, CW Doppler and power Doppler intensities. Shadowing in B-mode images of the phantom were found to be correlated with measured attenuation. The relationships established provide a first step toward more quantitative clinical assessment of contrast enhancement.