Real-time 3D pulse-echo ultrasonic imaging with coded-excitation systems

A new coded-excitation pulse-echo imaging system capable of simultaneous acquisition of a larger number of image lines for real-time 3D imaging is presented. A theoretical formulation of the system based on a discretized received signal model is given. With realistic simplifications, the image reconstruction is realized by a transversal filter bank with each filter designed to extract echoes from a specific direction in the region of interest. The filters are derived from a regularized pseudoinverse image reconstruction operator obtained from the system formulation. Unlike similar coded-excitation systems based on matched filtering, this pseudoinverse-based filter bank decouples echoes from different directions before providing matched filtering along the range direction. The correlation artifacts due to non-ideal coding are thus dramatically reduced. It can also be shown that the system may achieve lateral resolution exceeding the limit of conventional beamforming systems based on the same array. Both simulation and experimental results are provided