Angle sub-sampling methods for enhanced ultrasound coherent plane wave compounding

Coherent plane wave compounding ultrasound imaging combines low-resolution frames acquired from multiple angles to generate a high-quality image. However, achieving an optimal balance between frame rate and image quality is challenging, as increasing the number of emission angles leads to a reduction in frame rate. In scenarios with sub-sampled angles, selecting an optimal subset of angles becomes crucial to minimizing data acquisition time while preserving image quality comparable to all-angle transmission. To address this challenge, we propose two methods: Coprime sub-sampled angle (CSA) and semi sub-sampled angle (SSA). These approaches strategically select two subsets of angles to effectively suppress grating lobes resulting from down-sampling in the transmission angle intervals. Unlike traditional methods like random or periodic subsampling, CSA and SSA offer controlled and robust suppression of grating lobes while maintaining image quality, making them ideal for sub-sampled angle configurations. Our validation with the Plane-wave Imaging Challenge in Medical Ultrasound dataset shows that CSA achieves comparable resolution with an 8.4% contrast ratio improvement using only 25.3% of all available angles. Meanwhile, SSA achieves similar resolution with a 7.7% contrast gain, using 36% of the angles, while effectively preserving speckle quality.