THE INFLUENCE OF DIFFERENT GASES ON ACOUSTIC PROPERTIES OF A SPHEROSOME-BASED ULTRASOUND CONTRAST AGENT (BY963)

Ultrasound contrast agents improve the signal-to-noise ratio of reflec ted ultrasound, enhancing the diagnostic value of transcranial Doppler (TCD). In dog studies, we investigated the time course of TCD signal amplitude after application of a phospholipid-containing ultrasound co ntrast agent (BY963) filled with different gases. The median time of D oppler amplitude enhancement exceeding 5 dB was determined using isofl urane-, isopentane-, trichlortrifluoroethane-, air-, argon-, and perfl uoropentane-filled BY963 (69, 72, 75, 78, 88, and 245 seconds respecti vely). The decrease of time-intensity curve and the duration of signal enhancement showed significant differences comparing the different ga ses (p = 0.04 and 0.03, respectively). The time course of in vitro sta bility of BY963 agitated with the different gases measured by absorban ce of light (500 nm) showed a retarded decay for perfluoropentane, a r apid decrease for air, isopentane, trichlortrifluoroethane, and argon, and a very rapid decrease using isoflurane. The time course of the di fferent gases depended on the physicochemical properties (lipophilicit y and the solubility in water) of the gas encoated in the phospholipid shell. Perfluoropentane-filled BY963 showed the highest in vitro stab ility and the longest duration of TCD enhancement compared with the ot her gases used.