Image Quality Enhancement in Spectral-Domain Synthetic Transmit Aperture Ultrasound Imaging for 3D Volumetric Reconstruction Using Golay Coded Sequences

Spectral-domain (SD) ultrasound imaging techniques offer much faster reconstruction rates compared to conventional time-domain (TD) methods, such as synthetic transmit aperture (STA). Nevertheless, they often fail to deliver sufficient imaging depth, which remains a significant limitation. In this study, we propose employing coded transmission using Golay complementary coded sequences (GCCS) to enhance SD image reconstruction by improving imaging performance metrics such as signal-to-noise ratio (SNR) and visualization depth. Specifically, we introduce a modification to the 3D SD STA method (SD-STA) that integrates SD data processing with sub-aperture STA data acquisition and plane-wave transmission. This modification incorporates matched filtering and the compression of Golay-coded signals directly within the spectral domain, enhancing its efficiency in terms of transmission, detection, and processing of GCCS signals. The proposed imaging approach was validated using synthetic datasets generated with the Field II simulation program in MATLAB® and experimental data obtained from a perfect reflector and a commercial, general-purpose phantom using a Verasonics Vantage 256™ research ultrasound system equipped with a dedicated 1024-element 2D matrix transducer. We generated 16-bit Golay-coded sequences and measured key imaging performance metrics – namely axial resolution, SNR, side-lobe level (SLL), and visualization depth – comparing them against parameters obtained using a conventional short-pulse transmit signal. Experimental results demonstrated a 14 dB increase in echo amplitude when using GCCS with matched filtering. Furthermore, phantom tests under low-voltage conditions showed a ∼6 dB SNR gain and a twofold increase in imaging depth, both of which are consistent with simulation results.