Ultrasound Planar Array Imaging Metric Analysis

Planar array design makes the tradeoff between the 3-D ultrasound image quality and the system complexity based on the imaging metrics. The -6 dB mainlobe width (MW), mainlobe-to-sidelobe energy ratio (MSR), peak sidelobe level (PSL), and average sidelobe level (ASL) are the common imaging metrics for linear array design. MW is used for lateral resolution evaluation, while MSR, PSL, and ASL are adopted for contrast resolution evaluation. However, simulation results show that these metrics cannot fully evaluate the planar array performance. This article proposes several new imaging metrics for planar array: averaged mainlobe acoustic energy level and mainlobe energy density curve are the lateral resolution metrics, while mainlobe-to-sidelobe energy density ratio is the contrast resolution metric. The new metrics take into account the influence of the mainlobe area on the planar array performance evaluation. PSF analysis and simulated images show that the proposed metrics can evaluate planar array performance more accurately than the existing metrics. Moreover, uniform planar arrays with different scales and random sparse arrays are tested to show how to use the proposed metrics in planar array design.