Spatial Multi-Rate De-Aliasing with Multi-Row, Multi-Pitch Arrays for Fundamental Grating-Lobe Suppression in Ultrasound Imaging
Affiliation Type:
Academia
Keywords:
beamforming, grating lobes, multi-rate signal processing, multi-row arrays
Abstract:
Grating lobes are a fundamental barrier, particularly to high-frequency and 2-D ultrasound arrays, where meeting the spatial Nyquist limit imposes pitch constraints that are difficult to fabricate and that exacerbate inter-element crosstalk. Existing mitigations, such as aperiodic layouts or adaptive apodization, reduce artifact amplitudes but do not eliminate the underlying spatial aliasing. We extend time-domain multi-rate de-aliasing to the spatial domain by pairing a spatial de-aliasing algorithm with a multi-row, multi-pitch array that places two sub-Nyquist pitches on adjacent rows within a single aperture, thereby capturing correlated echoes whose overlapping spatial spectra are separated by the algorithm to recover unaliased channel data. Validated with Field II simulations and in vitro phantom measurements from a 5 MHz two-row array configured for sub-Nyquist sampling, the framework achieved ~10 dB and ~7 dB of grating-lobe suppression, respectively. Unlike conventional methods that only mitigate artifact amplitudes, this approach fundamentally resolves spatial aliasing, providing a deterministic design pathway for advanced multidimensional arrays.
