A Filter-Based Pulse-Echo Coded-Excitation System for Real-Time Cardiac Imaging

A new filter-breed approach to pulse-echo imaging capable of parallel processing of multiple image lines has been developed. A major application of this approach is in true real-time 3D imaging, e.g., in cardiac imaging. The new approach utilizes a set of coded waveforms on transmit and conventional beamforming on receive. The transmitted codes produce a coded wavefront in the region of interest (ROI) and the receive beam is designed to be wide enough to allow echoes from the ROI to be received while rejecting echoes from outside the ROI. Image formation is achieved using a filter bank structure (post-beamforming) with every filter designed to extract echoes from a given direction in the ROI. The filter bank is derived from a regularized pseudoinverse operator of the (discretized) propagation operator from the ROI to the receiving array. Image reconstructions from specklegenerating phantoms using the new approach demonstrate its robustness and its potential in medical imaging applications. A complete description of the algorithm and its fundamental spatial and contrast resolution limits will be presented with illustrative experimental data. System architectures for robust real-time implementation will be discussed.