Ultrasonic measurement of backscatter from embryonic mouse red blood cells in vivo

The mouse is a tremendously valuable animal model system in which to explore both normal development and human disease models. Because humans share approximately 95% of their genes with the mouse a large number of diseases such as congenital heart disease, cancer and atherosclerosis are now being studied. The present study focuses on the formation of the embryonic mouse heart and in particular on changes in backscatter intensities from the developing blood system. significant changes in brightness of the ultrasound images of the embryonic mouse heart at different ages of gestation have been observed. We hypothesize that these changes are due to the early development of Red Blood Cells (RBCs). In order to quantify these changes, measurements of the frequency dependence of the backscatter coefficient from blood within heart chambers were performed in utero and in vivo. For this calculation 100 radio-frequency lines were collected from the chambers of the embryonic mouse heart positioned at the focal zone of the probe, using a 40 MHz ultrasound biomicroscope (VisualSonics VS40). These signals were corrected for diffraction effects and the system transfer function in order to estimate the backscatter coefficient.