Effect of ultrasound transmit power on liver enhancement with Imagent® US, a PFC-stabilized microbubble contrast agent
✍ Scribed by Claude B. Sirlin; Michael S. Girard; Gregory C. Steinbach; Kristine G. Baker; Susan K. Broderdorf; Lisa A. Hall; Robert F. Mattrey
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 185 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0899-9457
No coin nor oath required. For personal study only.
✦ Synopsis
The pressure of the ultrasound wave may limit the lonultrasound scatterers and provide varying degrees of echogenic gevity of microbubble-based contrast agents. This study evaluated contrast [4,5,7,10,11]. The intensity of the reflected signal is reliver enhancement over time as a function of transmit power after lated to the sixth power of the bubble's radius [12] and linearly the administration of AFO145 (Imagent US; Alliance Pharmaceutical related to bubble concentration [10,[13][14][15]. The bubbles in Corp., San Diego, CA). Eight rabbits with an avascular liver lesion plasma have comparable dimension and similar rheology as red created by percutaneous injection of 1.0 ml of ethyl alcohol 7 days blood cells and therefore are capable of passage through the prior to scanning were imaged with an Acuson 128XP/10 at 7 MHz pulmonary, systemic, and capillary circulation [2,10,.
before and after four separate intravenous injections of 0.25 ml of Although necessary for transpulmonary passage, the small AFO145 spaced at least 1 h apart. The avascular lesion served as an internal standard against which liver enhancement could be com-bubble size (õ5-8 mm) decreases the longevity of the contrast pared. After contrast injection, scanning over the same plane was effect. A small size is associated with a high surface tension either continuous at (a) maximum or (b) minimum transmit power ( (LaPlace pressure) which, together with the ambient pressure, dB below maximum), or intermittent at (c) minimum power for 5 s exerts a collapsing force that promotes the rapid diffusion of the every 15 s, or (d) for 5 s every 60 s. Each session was terminated highly plasma-soluble air gases out of the bubble, leading to after 15 min or when contrast was no longer visible in the hepatic bubble collapse and loss of reflectivity [11,13,17] within seconds.
parenchyma and blood vessels. Videodensitometry was used to as-
The addition of a protective shell increases bubble longevity to sess liver-to-lesion intensity difference over time. Both the degree one or a few circulation times (approximately 1 min) after intraveand duration of liver enhancement were dependent on the transmit nous injection [11,[19][21], but early-generation bubbles remain power. Liver enhancement with imaging at minimum power for 5 s/ min was nearly two times greater and persisted nearly eight times highly susceptible to hydrostatic pressure as shown by the in vivo longer (P õ 0.01) than at maximum power and continuous insonation.
observation of systolic disappearance of left ventricular contrast
Ultrasound transmit power affects both the peak and duration of liver [22] and by numerous in vitro [13,15,[23][24][25] and isolated heart enhancement. A lower power and shorter insonation time after
[3] experiments.
AFO145 administration dramatically lengthens the imaging window
Several late-generation agents are currently in development for liver lesion detection.