Effect of US contrast agents on spectral velocities: In vitro evaluation

PURPOSE: To evaluate the effect of ultrasonographic (US) contrast agents on measurements of peak velocity with spectral Doppler US in stenotic and non stenotic flow states. MATERIALS AND METHODS: Nonpulsatile flow was established in a flow phantom with 0%, 50%, 75%, and 90% stenoses. SH U 508A perflenapent emulsion, and p erfluorohexane emulsion were the contrast agents evaluated. Before and afte r administration of each contrast agent, two peak velocity measurements obt ained proximal to, at the site of, and distal to the stenosis in each vesse l model were averaged. The percentage difference in peak velocity after con trast agent administration was calculated for each site interrogated. The m ean, SD, and coefficient of variation of the percentage difference in peak velocity were calculated. RESULTS: Percentage differences in peak velocity after contrast agent admin istration at different sample volume sites were not significantly different irrespective of the degree of stenosis or the contrast agent evaluated. CONCLUSION: The contrast agents evaluated do not produce a statistically si gnificant increase in peak velocity. If this result is corroborated in clin ical practice, contrast agents can be used without reevaluating existing Do ppler US thresholds for stenosis.