title: Contrast imaging in mouse embryos using high-frequency ultrasound.
abstract: Ultrasound contrast-enhanced imaging can convey essential quantitative information regarding tissue vascularity and perfusion and, in targeted applications, facilitate the detection and measure of vascular biomarkers at the molecular level. Within the mouse embryo, this noninvasive technique may be used to uncover basic mechanisms underlying vascular development in the early mouse circulatory system and in genetic models of cardiovascular disease. The mouse embryo also presents as an excellent model for studying the adhesion of microbubbles to angiogenic targets (including vascular endothelial growth factor receptor 2 (VEGFR2) or αvβ3) and for assessing the quantitative nature of molecular ultrasound. We therefore developed a method to introduce ultrasound contrast agents into the vasculature of living, isolated embryos. This allows freedom in terms of injection control and positioning, reproducibility of the imaging plane without obstruction and motion, and simplified image analysis and quantification. Late gestational stage (embryonic day (E)16.6 and E17.5) murine embryos were isolated from the uterus, gently exteriorized from the yolk sac and microbubble contrast agents were injected into veins accessible on the chorionic surface of the placental disc. Nonlinear contrast ultrasound imaging was then employed to collect a number of basic perfusion parameters (peak enhancement, wash-in rate and time to peak) and quantify targeted microbubble binding in an endoglin mouse model. We show the successful circulation of microbubbles within living embryos and the utility of this approach in characterizing embryonic vasculature and microbubble behavior.
authors: Department of Medical Biophysics, University of Toronto; Sunnybrook Research Institute; Janet.denbeigh@utoronto.ca.
authors: Janet M
authors: JM
authors: Denbeigh
authors: Department of Medical Biophysics, University of Toronto; Sunnybrook Research Institute.
authors: Brian A
authors: BA
authors: Nixon
authors: Department of Medical Biophysics, University of Toronto; Sunnybrook Research Institute; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto.
authors: Mira C
authors: MC
authors: Puri
authors: Department of Medical Biophysics, University of Toronto; Sunnybrook Research Institute.
authors: F Stuart
authors: FS
authors: Foster
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D004622:Embryo, Mammalian / Q000098:blood supply / Q000000981:diagnostic imaging*; D000071063:Endoglin; D005260:Female; D007089:Image Enhancement / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051379:Mice / Q000196:embryology*; D008822:Mice, Transgenic; D045423:Microbubbles; D015203:Reproducibility of Results; D014465:Ultrasonics / Q000379:methods*; D014463:Ultrasonography; D040301:Vascular Endothelial Growth Factor Receptor-2
chemical_list: D003287:Contrast Media; D000071063:Endoglin; C502004:Eng protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D040301:Vascular Endothelial Growth Factor Receptor-2