Estimation method for sound velocity distribution for high-resolution ultrasonic tomographic imaging.

PURPOSE: With commercial ultrasonic equipment, the sound velocity is fixed to a constant value of 1530 or 1540 m/s, which is used for beam formation. However, the assumption of a constant sound velocity is not optimal, as the sound velocity in a living body is heterogeneous. In this study, a novel method was proposed to estimate the distribution of the sound velocity in a region of interest.

METHODS: The sound velocity distribution was estimated by fitting the theoretical propagation time of the ultrasonic wave from the scatterer to each of the probe elements with measured values.

RESULTS: In a phantom experiment, the sound velocity distribution was estimated by the proposed method with a maximum estimation error of 0.6%, and the resultant local sound velocity values successfully improved the quality of the ultrasonic image.

CONCLUSION: The proposed method has the potential to improve ultrasonic image quality in in vivo experiments by estimating the sound velocity distribution.