Signal Eigenvalue Factor for Synthetic Transmit Aperture Ultrasound Imaging

Synthetic transmit aperture (STA) ultrasound imaging that obtain bi-directional focusing can create a high-resolution image. Delay-and-sum (DAS) approach is performed in both transmit and receive modes, which leads to low contrast and high sidelobe. Adaptive weighting technology is effective in improving image quality. This paper proposes a new adaptive weighting factor namely signal eigenvalue factor (SEF) for STA imaging. SEF performs eigenvalue decomposition on transmitting aperture, and then it uses the larger eigenvalues as the weighting factor to carry out the adaptive imaging. For comparison, conventional coherence factor (CF) method is also presented. Simulation and experimental results show that SEF method can get higher resolution than CF and DAS. In addition, the contrast radio and contrast-to-noise radio can be enhanced, especially for massive cyst.