Grating-lobes reduction by application of Phase Coherence Factors

Phase Coherence Imaging (PCI) has been recently proposed as a robust method to improve the quality of ultrasound images. Based on a statistical analysis of the instantaneous phase of the aperture data, a Phase Coherence Factor (PCF) is computed for every sampling instant. When used to weight the beamformer output, side and grating lobe levels are reduced and lateral resolution is increased. In this work, its application for grating lobe artifacts reduction is further investigated. Dependence of grating lobes reduction level with signal bandwidth and the number of array elements is analyzed and detection of low amplitude echoes located into the grating lobe region is addressed. Experimental data obtained with a 2-D matrix sparse array are presented. In a second experiment, a standard tissue-mimic phantom and a sparse linear array are used to evaluate the PCI grating lobe reduction performance for medical images.