Non-elevation-focused probe (NEFP) designed for pure plane-wave ultrasound imaging

Plane-wave ultrasound imaging has been widely used in many frontier research areas in medical ultrasound due to its ultra-high frame rate. To improve its image quality, many novel beamforming methods have been proposed and in-depth studied, such as coherent compounding method and methods based on compressive sensing. However, the influence of the structure and working mode of the ultrasound probe on the image's lateral resolution and contrast is still rarely studied. Convenient ultrasound probe is always self-focused with an acoustic len in the elevation direction, and thus the acoustic energy distributed in the y-z plane is not uniform. We hypothesized that, if the probe is not focused in the elevation direction, the quality of the image obtained with a kind of “pure plane-wave” will be increased. To verify our hypothesis, the non-elevation-focused probe (NEFP) was fabricated, and the plane-wave ultrasound images obtained with NEFP were compared with those obtained with the traditional elevation-focused probe (EFP). The experiments were conducted with a ultrasound driven/acquire system and a general purpose ultrasound imaging phantom. The two images were obtained with coherent compounding method by 9 plane-wave images. The image obtained using NEFP visually has a lower speckle noise background than the one obtained using EFP in the shallow region. It is shown that, in the deeper region, the contrast of NEFP image are much better than the EFP image. However, the difference of their lateral resolution is unapparent. The results of this study indicates that, the NEFP probe is actually better than EFP probe in some respects, and this may provide us an additional way to enhance the image quality of plane-wave ultrasound imaging technique.