Enhancement characteristics of the microbubble agent Levovist: reproducibility and interaction with aspirin

We investigated the reproducibility of Doppler enhancement indices following intravenous bolus injections of Levovist (Schering AG, Berlin) microbubbles. We also aimed to determine whether observations from animal studies suggesting that aspirin potentiates microbubble enhancement were reproducible in humans. In five healthy volunteers, time enhancement profiles of Doppler intensity following repeated bolus injections of Levovist were acquired from the common carotid artery, hepatic vein and kidney using spectral and power Doppler before and after oral aspirin (600 mg). Peak enhancement (PE), area under the curve (AUC) and decay slopes (lambda) were calculated. Hepatic vein contrast arrival time (AT) was determined subjectively. Well-defined carotid enhancement was seen in 19/20 injections. Reproducibility was high (r > 0.8). PE and AUG were unaffected by aspirin, but lambda was slightly reduced (P = 0.02). Renal power Doppler profiles were well defined (10/10) with no significant changes of AUC, PE or lambda after aspirin. Our study demonstrates good reproducibility of carotid spectral Doppler time intensitometry with Levovist in man. Aspirin does not have a significant effect on enhancement indices except carotid spectral Doppler decay. We conclude that aspirin is unlikely to potentiate microbubble enhancement, as seen in animal studies.