A new ultrasound instrument for in vivo microimaging of mice.

We report here on the design and evaluation of the first high-frequency ultrasound (US) imaging system specifically designed for microimaging of the mouse. High-frequency US or US biomicroscopy (UBM) has the advantage of low cost, rapid imaging speed, portability and high resolution. In combination with the ability to provide functional information on blood flow, UBM provides a powerful method for the investigation of development and disease models. The new UBM imaging system is demonstrated for mouse development from day 5.5 of embryogenesis through to the adult mouse. At a frequency of 40 MHz, the resolution voxel of the new mouse scanner measures 57 microm x 57 microm x 40 microm. Duplex Doppler provides blood velocity sensitivity to the mm per s range, consistent with flow in the microcirculation, and can readily detect blood flow in the embryonic mouse heart, aorta, liver and placenta. Noninvasive UBM assessment of development shows striking similarity to invasive atlases of mouse anatomy. The most detailed noninvasive in vivo images of mouse embryonic development achieved using any imaging method are presented.