Use of Ultrasound Contrast Agent Microbubbles in Preclinical Research

Abstract

Ultrasound contrast imaging techniques represent a real opportunity to improve efficiency in the preclinical drug discovery and development process. Ultrasound contrast agents (UCAs) combined with specific ultrasound contrast detection modes provide real-time, high spatial resolution of both organ and lesion blood perfusion, the so-called dynamic contrast-enhanced ultrasound imaging. With the advent of targeted UCA, ultrasound molecular imaging is gaining momentum in molecular imaging, particularly because of the simultaneous real-time anatomical and functional/molecular imaging capabilities. In preclinical research, contrast-enhanced ultrasound imaging, with either nontargeted or targeted UCA, is a fast-growing imaging modality that has not yet been standardized compared with other imaging modalities. Contrast-enhanced ultrasound imaging is an operator-dependent imaging modality, requiring adherence to rigorous step-by-step protocols. In this article, which is intended for advanced, hands-on researchers, we report key factors that can lead to variability in preclinical results and recommend some preventive methods to limit or cancel their effect on the final results. Standardized procedures are a prerequisite for acceptance of new contrast-enhanced ultrasound imaging methods to eliminate factors that could distort results, improve the reproducibility between different centers and studies, and, therefore, allow translation to clinical application.

Analysis of Liver Tumors Using Preoperative and Intraoperative Contrast-Enhanced Ultrasound (CEUS/IOCEUS) by Radiologists in Comparison to Magnetic Resonance Imaging and Histopathology

“…The higher intraoperative dose can be attributed to an increased destruction rate of the microbubbles in ventilated patients in connection with the oxygen content of the inhalation gas [20]. The correlation to other protocols also yielded a higher contrast dose under surgical conditions [19].…”

VEGFR2-Targeted Contrast-Enhanced Ultrasound to Distinguish between Two Anti-Angiogenic Treatments

“…BR55 microbubbles were used for the assessment of vascularization ) and VEGFR2 expression (Hyvelin et al 2013). A lipopeptide showing strong and selective interaction with human and murine VEGFR2 is incorporated into the BR55 shell (Pillai et al 2010;Shrivastava et al 2005).…”

“…After 10 s, data were acquired for 10 s to assess recirculating bubbles ( Fig. 1) (Hyvelin et al 2013;Pochon et al 2010;Tardy et al 2010;Willmann et al 2008). Throughout the imaging session, mice were kept on a thermostatically heated stage and anesthetized with 1.5% isoflurane in medical air at 1 L/min (Constantinides et al 2011).…”

“…Injection was performed automatically using a syringe pump in a controlled system implemented in our laboratory and based on a system developed by Bracco Suisse (Dizeux et al 2012;Hyvelin et al 2013). The microbubbles were injected into the tail vein at a dose of 1 mL/kg to provide approximately 5 3 10 7 MBs (Pysz et al 2010).…”

“…Differential targeted enhancement (dTE) was then calculated as signal pre-destruction minus signal post-destruction ( Fig. 1) (Hyvelin et al 2013;Willmann et al 2008). Because of the heterogeneous BR55 uptake, dTE was estimated only in the area of the tumor that exhibited microbubble uptake at any time during the time course of the acquisition, according to the criteria described under Vascularization assessment.…”