Enhanced Diverging-Wave Iterative Adaptive Approach Beamforming Using Spatial Subspace Filtering
Affiliation Type:
Academia
Keywords:
Diverging Wave, Adaptive beamforming, High Frame Rate imaging
Abstract:
Diverging wave (DW) imaging achieves high frame-rate ultrasound by covering wide fields using few transmissions. However, adaptive beamformers like the Iterative Adaptive Approach (IAA) assume received echoes are spatially coherent and narrowband with respect to a specific steering direction. Wide-angle insonification introduces incoherent, off-axis signal components that violate this assumption, degrading both contrast and resolution. We address this limitation while enhancing image quality without increasing the number of transmissions. We introduce a spatial pre-filtering step between time-delay focusing and IAA beamforming. The focused data is projected onto a low-rank subspace spanned by Discrete Prolate Spheroidal Sequences (DPSS), selectively preserving directionally coherent signals while attenuating off-axis interference. This filtering mimics the angular selectivity of focused or compounded transmit acquisitions without requiring additional transmissions. Angular pre-filtering in our method enhances IAA beamforming in diverging-wave imaging by selectively suppressing post-time-delay off-axis interference, thereby improving both contrast and resolution, without requiring additional transmissions.
