Objective: To evaluate the influence of different Doppler system settings on time-intensity curves after ultrasound contrast agent (UCA) bolus injection. This is important for the comparison of different UCAs.
Methods: Six sedated dogs were investigated with a transcranial Doppler system and Doppler power, sample volume size and high pass filter settings were modified during the procedure. Mean time intensity curves were determined and peak values of mean intensity as well as the decrease in Doppler intensity were compared for the different system settings. Three different UCAs were used (SonoVue(TM), BY963 and Levovist(TM)).
Results: The Doppler time intensity curves showed a typical two phase decrease with a distribution phase alpha and an elimination phase beta with all three UCAs. Altering the system settings had a significant effect on the mean peak Doppler intensity for SonoVue(TM) (P=0.02) but not for BY963 or Levovist(TM) (P=0.07 and P=0.39, respectively), due to high variation of the Levovist(TM) and BY963 intensity values. There were no significant differences between the alpha slopes of BY963 and Levovist(TM) (P=0.96), or the beta slope of Levovist(TM) and SonoVue(TM) (P=0.62), when the results of all system settings were combined.
Conclusion: Different Doppler system settings show no significant influence on the decrease of mean Doppler intensity, but have a significant effect on peak intensity.