40 MHz Doppler characterization of umbilical and dorsal aortic blood flow in the early mouse embryo

Cardiovascular Assessment of Fetal Mice by In Utero Echocardiography

“…Due to differences in experimental procedure and equipment design, it is difficult to make comparisons with ultrasound studies carried out with ultra-high frequency biomicroscopes. In some of the biomicroscope studies, a semi-invasive procedure involving exteriorizing the uterine horns was used, which can affect lhemodynamic function (Phoon et al, 2000(Phoon et al, , 2004. The slower frame rates of biomicroscopes (8-30 Hz as compared to 60 Hz in clinical ultrasound systems) also made it difficult to obtain images of the heart at true end-diastole and end-systole.…”

“…Mouse fetal echocardiography has been carried out using standard clinical ultrasound systems (Gui et al 1996;Spurney et al 2004), as well as ultra-high frequency ultrasound systems, also referred to as ultrasound biomicroscopes (Srinivasan et al 1998;Phoon et al 2000Phoon et al , 2004Foster et al 2002;Zhou et al 2002Zhou et al , 2003. Ultra high frequency ultrasound systems equipped with 30-40 MHz transducers have greatly improved 2D spatial resolution that allow even very early mouse embryos (from embryonic day 5.5) to be imaged (Srinivasan et al 1998;Phoon et al 2000;Foster et al 2002).…”

“…Ultra high frequency ultrasound systems equipped with 30-40 MHz transducers have greatly improved 2D spatial resolution that allow even very early mouse embryos (from embryonic day 5.5) to be imaged (Srinivasan et al 1998;Phoon et al 2000;Foster et al 2002). However, the higher ultrasound frequencies cause reduced penetration depth, making it more difficult to obtain optimal ultrasound imaging planes for cardiac assessments (Zhou et al 2003).…”

“…However, the higher ultrasound frequencies cause reduced penetration depth, making it more difficult to obtain optimal ultrasound imaging planes for cardiac assessments (Zhou et al 2003). To overcome this limitation in imaging depth, mouse fetuses examined by ultrasound biomicroscopy have been exteriorized (Phoon et al, 2000(Phoon et al, , 2004, which raises some concerns that hemodynamic function may be perturbed. In contrast, clinical ultrasound systems have higher penetration depth, and as result, the acquisition of images in the desired ultrasound imaging planes is greatly facilitated.…”

Multimodal imaging of mouse development: Tools for the postgenomic era

“…Since the initial study of mouse embryos in utero (Turnbull et al, 1995a), ultrasonography has been used for imaging and staging early postimplantation embryos in utero (Turnbull, 1999;Chang et al, 2003), and both transcutaneous and transuterine UBM has become a standard method for assessing normal and defective cardiovascular development in mice (Srinivasan et al, 1998;Fatkin et al, 1999;Phoon et al, 2000Phoon et al, , 2002Phoon et al, , 2004Ji et al, 2003;Phoon and Turnbull, 2003;Lickert et al, 2004;Mai et al, 2004;Ji and Phoon, 2005). Many of these studies have also used Doppler echocardiography, a highly sensitive method for measuring the direction and velocity of blood flow (see Phoon and Turnbull, 2003, for review).…”