A Comparative Study of the Hepatic Transit Time (HTT) of Different Ultrasound Contrast Agents in Patients with Liver Metastases and Healthy Controls

Purpose: Liver metastases lead to a shortening of the HTT of an echo enhancer. Studies using SonoVue T also showed a shortening of the HTT in healthy controls. Hence the HTT depends on the applied contrast agent. We examined whether the HTT of SonoVue (TM), Luminity (TM) und Levovist (TM) is useful to discriminate between patients with and without liver metastases. Materials and Methods: We compared the arteriovenous HTT of Levovist (TM), Sonovue (TM) und Luminity (TM) T in 20 patients with liver metastases and in 15 controls. An Acuson Sequoia (TM) ultrasound system was used. The HTT results from the difference of the arrival time of the microbubbles in the hepatic artery and a hepatic vein. Results: Using Levovist T six patients and three controls had to be excluded from further analysis. The arrival time was undetectable. The mean HTT values in healthy controls were: Levovsit (TM) 14.75 sec (SD +/- 2.53 sec), SonoVue (TM) 9.27 sec (SD +/- 2.41 sec) and Luminity (TM) 9.2 sec (SD +/- 2.34 sec). In patients the mean HTT values were: Levovist T 9.89 sec (SD +/- 1.04 sec), SonoVue (TM) 6.28 sec (SD +/- 2.41 sec) and Luminity (TM) 6.33 sec (SD +/- 1.37 sec). Using a cut off of 8 sec for SonoVue T and Luminity T, the sensitivity to exclude liver metastases was 75% and 80%. Conclusion: The mean HTT values of all contrast agents were shorter in patients. Levovist T showed a longer HTT in patients and controls than Luminity T and SonoVue T. Levovist T showed the best separation between patients and controls but some patients and controls had to be excluded. The HTT could still be a useful tool to exclude liver metastases but the HTT depends on the contrast agent and the applied contrast technique.