A computationally efficient pulse compression method of Barker-coded excitation using a mismatched filter in medical ultrasound imaging.

purposeBarker-coded excitation, which is well suited for portable ultrasound imaging because it preserves frame rate and uses binary encoding, exhibits a high range sidelobe level of 1/N after pulse compression. This limitation can be mitigated by employing a mismatched filter, albeit at the cost of increased computational complexity. This study proposes a pulse compression technique that applies a mismatched filter for Barker-coded excitation with reduced computational complexity.

methodsIn the proposed method, pulse compression is performed using complex baseband in-phase and quadrature (IQ) data after decimation rather than beamformed radio-frequency (RF) data. By decimating both the IQ data and the coefficients of the compression filter, hardware complexity can be reduced by a factor of L² (where L is the decimation factor) through the use of time-shared multipliers. The proposed approach was implemented in a custom-built portable ultrasound imaging system, and its performance was evaluated through simulations as well as phantom and in vivo experiments.

resultsFrom the simulation and phantom experiments, the proposed method achieved an identical -6 dB axial resolution compared to the conventional approach, i.e., pulse compression using RF data. The range sidelobes were comparable between the conventional and proposed methods, and consistent results were also obtained in the in vivo experiment.

conclusionThese findings demonstrate that the proposed method substantially reduces computational complexity while maintaining pulse compression performance.