Use of the galactose-based contrast agent SHU 508A (Levovist) in renal ultrasonography of the dog

Contrast-enhanced ultrasound analysis of renal perfusion in normal micropigs

Contrast-enhanced ultrasound is one of method for evaluating renal perfusion. The purpose of this project was to assess perfusion patterns and dynamics in normal micropig kidney using ultrasonographic contrast media. Eight young healthy micropigs were included in this study. Micropigs were anesthetized with propofol and received an intravenous bolus of microbubble contrast media through an ear vein. Time/mean pixel value (MPV) curves were generated for selected regions in the right renal cortex and medulla. The parenchyma was enhanced in two phases. The cortex was first enhanced followed by a more gradual enhancement of the medulla. A significant difference in perfusion was detected between the cortex and medulla. Following the bolus injection, the average upslope was 0.68 ± 0.27 MPV/sec, downslope was -0.27 ± 0.13 MPV/sec, baseline was 73.9 ± 16.5 MPV, peak was 84.6 ± 17.2 MPV, and time-to-peak (from injection) was 17.5 ± 6.6 sec for the cortex. For the medulla, the average upslope was 0.50 ± 0.24 MPV/sec, downslope was -0.12 ± 0.06 MPV/sec, baseline was 52.7 ± 7.0 MPV, peak was 65.2 ± 9.3 MPV, and time-to-peak (from injection) was 27.5 ± 5.0 sec. These data can be used as normal reference values for studying young micropigs.

Enhancement of ultrasound contrast agent in high-intensity focused ultrasound ablation

High-intensity focused ultrasound (HIFU) is becoming an increasingly attractive modality for ablation. Enhancement of HIFU is an important issue that has been discussed and investigated worldwide. Ultrasound contrast agents are considered to constitute an efficient medium for changing acoustic characteristics and improving energy deposition in the focal region. The role of microbubbles in inducing enhanced heating, cavitation, and other related events in HIFU ablation has been investigated, with the goal of improving coagulation necrosis volume or decreasing acoustic power and exposure duration. Consequently, with the use of ultrasound contrast agents, applications of HIFU are expected to become more efficient, safe, and accurate and to produce fewer adverse effects. This paper reviews studies that have been conducted to investigate the enhancement of ultrasound contrast agents in HIFU ablation through experiments that were carried out in vitro and in vivo; an analysis of results of this enhancement mechanism is provided.