A high frequency endoscopic ultrasound imaging method combining chirp coded excitation and compressed sensing.

Insufficient imaging penetration and large data acquisition are two of the major challenges of high-frequency ultrasound imaging. Based on the good autocorrelation properties of chirp signal and the feasibility of using compressed sensing theory to reconstruct high-quality ultrasound images with low sampling requirements, this paper proposed a chirp coded excitation combined with compressed sensing (CCE-CS) technique for high-frequency endoscopic ultrasound (HFEUS) imaging. The feasibility of the method was verified by a brief theoretical analysis, and the relevant parameters were selected and analyzed according to the actual engineering situation. Simulated phantoms and in-vitro tissue experiments were used to evaluate the performance of the CCE-CS. Simulation results demonstrate that CCE-CS is capable of reducing the impact of reconstruction errors and improving imaging quality through comparison with conventional methods. The reduction of reconstruction data had less impact on penetration depth, resolution and general contrast general contrast-to-noise ratio (gCNR), and the reconstructed image was closer to the original image with a maximum improvement of 37% in peak signal-to-noise ratio (PSNR). Moreover, comparisons were conducted on the digestive tract of swine, and the results show that CCE-CS is also feasible in the in-vitro environment. These results demonstrated that CCE-CS method has good potential for application to improve the imaging quality of HFEUS while reducing the sampling rate.

Surface Texturing Design to Enhance Echogenicity of Biopsy Needles During Endoscopic Ultrasound Imaging.

The ultrasonic visibility of a biopsy needle tip is of critical importance for the success and safety of endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) procedures. The aim of this study was to design a surface topology, in silico, which enhances the ultrasound visibility of a needle by controlling and optimising the direction of the reflections. Topographic enhancements to needle surface redirect scattered waves back to the transducer to enhance needle visibility, or "echogenicity." Echogenicity enhancement is demonstrated across insonification angles of 30°-90° on full-length scale of biopsy needles used in practice. By applying a textured surface across the full length of the needle surface, the signal being returned to the transducer can be tripled from that of a constant periodic dimple echogenic surface and seven times that of an untextured flat surface. Our first principles model provides a quantitative insight to echogenicity and its enhancement. The model allows in silico design of needles for USG-FNA and biopsy with enhanced echogenicity and consequent improvement in visibility, including but not limited to needle tip area.