2I-5 Analysis of 40 MHz Annular Array Imaging Performance In Mouse Embryos

Current high frequency ultrasound imaging, or ultrasound biomicroscopy (UBM) systems have the capability of imaging mouse embryos with a frame rate of up to 200 frames per second. 3D datasets can also be acquired with the appropriate hardware. Because of the limited depth of field (DOF), effective volumetric analysis is limited to approximately 2 mm about the passive focus for a fixed-focus transducer operating at 40 MHz. This shortcoming imposes a size limit which the current technology can effectively be used to segment out accurate volumetric anatomy of the embryonic mouse, Previously we reported the fabrication a five-element 40-MHz annular array and an array imaging system. Wire phantom measurements with this array reveals an increase in DOF from 1-2 mm (fixed-focus) to more than 10 mm with array focusing. When imaging attenuating media such as mouse embryos, it is expected that the figures of merit for the array images, such as the signal to noise ratio (SNR) and the depth of field (DOF) will be reduce. Images from mouse embryos from at gestational ages 11 (E11.5) and 13 (E13.5) were acquired with this annular array system, and show the superior image definition and quality over the fixed-focus images. Quantitative estimates of the SNR and DOF were calculated, and segmentation of the brain ventricles was accomplished for both gestational ages