Quantification of microbubble destruction of three fluorocarbon-filled ultrasonic contrast agents

The assessment of myocardial blood velocity using ultrasonic contrast agent s is based on the premise that the vast majority of contrast microbubbles w ithin a myocardial region can be destroyed by an acoustic pulse of sufficie nt magnitude. Determination of the period of time after destruction that a region of myocardium needs to reperfuse may be used to assess myocardial bl ood velocity. In this study, we investigated the acoustic pressure sensitiv ity of three solutions of intravenous fluorocarbon-filled contrast agents a nd the magnitude of acoustic pulse required to destroy the contrast agent m icrobubbles. A novel tissue-mimicking phantom was designed and manufactured to investigate the relationships between mean integrated backscatter, inci dent acoustic pressure and number of frames of insonation for three fluoroc arbon-filled contrast agents (Definity(R), Optison(R), and Sonazoid(R), for merly NC100100), Using a routine clinical ultrasound (US) scanner (Acuson X P-10), modified to allow access to the unprocessed US data, the contrast ag ents were scanned at the four acoustic output powers. All three agents init ially demonstrated a linear relationship between mean integrated backscatte r and number of frames of insonation. For all three agents, mean integrated backscatter decreased more rapidly at higher acoustic pressures, suggestin g a more rapid destruction of the microbubbles, In spite of the fact that t here was no movement of microbubbles into or out of the beam, only the resu lts from Definity(R) suggested that a complete destruction of the contrast agent microbubbles had occurred within the total duration of insonation in this study, (C) 2000 World Federation for Ultrasound in Medicine & Biology.