Infusion versus bolus of an ultrasound contrast agent - In vivo dose-response measurements of BR1

RATIONALE AND OBJECTIVES. TO determine the efficacy of an ultrasound contrast agent infusion using Doppler intensitometry estimation of backscatter enhancement in blood, METHODS. Multiple intravenous injections of BR1 (SonoVue) were performed in chronic dog studies, using bolus (0.05-2 mL) and infusion (3-40 mL/h during 6 minutes) administration. The pulsed Doppler signal from the femoral artery was recorded and analyzed for mean Doppler power and integrated fractional enhancement, RESULTS. For bolus injection, time-intensity curves exhibited a rapid first pass (peak 30 dB for 0.45 mL) followed by a slower washout. Integrated fractional enhancement exhibited a Linear relation with the dose (R-2 = 0.99). For infusion administration, peak enhancement increased with the infusion rate from 8 to 22 dB, At rates exceeding 30 mL/h, the enhancement was stable with a plateau-like pattern. CONCLUSIONS. Infusion of BR1 is easily achieved and allows the duration of enhancement to be increased as long as desired. Stable enhancement is obtained for rates greater than 30 mL/h.