DIFFERENCES IN MYOCARDIAL CONTRAST PRODUCED WITH TRANSIENT-RESPONSE IMAGING WHEN USING INTRAVENOUS MICROBUBBLES CONTAINING GASES OF DIFFERENT MOLECULAR-WEIGHT

The purpose of this study was to determine the effect of different mic robubble gases on. the amount of myocardial contrast (MC) produced fro m intravenously (TV) injected dextrose albuinin microbubbles when usin g a new imaging modality termed transient response imaging (TRI). In 6 dogs (4 closed chest, 2 open chest) the peak anterior myocardial vide ointensity (PMVI) and visual degree of MC were determined following IV injections of equivalent doses of perfluorocarbon exposed sonicated d extrose albumin (PESDA), sulfur hexafluoride-exposed sonicated dextros e albumin (SHESDA), and room air exposed sonicated dextrose albumin (R ASDA) microbubbles. TRI was performed by triggering ultrasound impulse s to I point every one to two cardiac cycles. The PMVI produced with T RI was compared to conventional 30 Hz frame rate imaging (CI) for each gas. Visual anterior and posterior MC was evident with TRI in, all si x: dogs using PESDA, but not in any dog with CI. Although RASDA and SH ESDA did not produce MC with CI, visually evident anterior MC was seen after 7 of 8 SHESDA and 4 of 9 RASDA injections when using TRI with b oth gases. PESDA produced the higest peak PMVI of all three microbubbl es when using TRI, while SHESDA produced a significantly higher PMVI t han RASDA. We conclude that although MC can be produced with TRI using microbubble gases of lower molecular weight, the brightest and most c onsistent contrast is produced with fluorocarbon. containing microbubb les.