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 contra st agent infusion using Doppler intensitometry estimation of backscatter en hancement 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 durin g 6 minutes) administration. The pulsed Doppler signal from the femoral art ery was recorded and analyzed for mean Doppler power and integrated fractio nal 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 fra ctional 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 stabl e 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 obtai ned for rates greater than 30 mL/h.