Suppression of Grating Lobe Artifacts in Ultrasound Images Formed from Diverging Transmitting Beams by Modulation of Receiving Beams

Abstract

In linear array transducers, owing to regular spacing of the array elements, grating lobes exist in transmission and reception. In ultrasonic imaging involving the use of diverging (unfocused) transmitting beams and steered receiving beams by linear transducer arrays, aperture apodization and spatial combination of steered receiving beams from multiple transmissions are not sufficient to suppress receive-grating lobe artifacts. To further suppress receive-grating lobe artifacts in reconstructed B-mode images, we propose a technique of modulating the receiving beams by a factor that is governed by the envelope of a corresponding signal, which is formed by filtering the receiving beam with a zero-phase low-pass filter with a cut-off frequency that is determined by the receiving beam steering angle. This technique suppressed receive-grating lobe artifacts without significant loss in spatial resolution in offline reconstructed B-mode images from simulation, phantom and in vivo imaging of the carotid artery. In a simulation of point scatterers, a relative reduction in grating lobe artifacts of 40 dB was realized in images from diverging beam scanning.