2021 FDA Science Forum
Developing a Test Method for Acoustic Characterization of an Ultrasound Contrast Agent
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Contributing OfficeCenter for Devices and Radiological Health
Abstract
Ultrasound contrast agents (UCA) have been approved by FDA for improving echocardiography and ultrasonography in the liver and urinary tract. This study aims to develop UCA acoustic characterization methodology in order to find critical physical properties to evaluate different UCA products. LumasonTM (sulfur hexafluoride lipid type-A microbubble suspension) was selected as a FDA-approved UCA for this study. The dependence of microbubble echogenicity on various physical properties was evaluated. For example, the backscattering performance is an important effectiveness parameter in ultrasonography. A theoretical simplification of the multi-bubble backscattering property was derived and compared with experimentally obtained data of UCAs. The backscattering coefficients of varying dilutions (500×, 1000×, 2000×, 4000×, and 10000× in 0.9% sodium chloride at room temperature) was measured using a broadband pulse echo technique with a circular focused (1.5” focal length) broadband transducer. The microbubble size distribution and concentration were also measured using a Beckman Coulter Counter 4e. The final results of the backscattering property demonstrated a dependence on acoustic frequency and bubble volume density, matching our experimental observation. This work could streamline the acoustic bench testing protocol; thereby, improving the FDA regulatory review process for future UCA products.
