Effective Hyper-clutter Artifacts Suppression for Ultrafast Ultrasound Doppler Imaging

Objective: Hyper-clutter artifacts (HCA), arising from strong tissue reflections or physiological motion, present persistent challenges in ultrafast ultrasound Doppler imaging, often obscuring surrounding small vessel flow signals, especially in fascial regions such as the renal capsule. This study proposes U-profile-based decluttering (UPBD), a robust and computationally efficient method that exploits singular value decomposition (SVD)-derived spatial singular vectors to suppress HCA in ultrafast Doppler imaging. Methods: UPBD analyzes intensity profile of each pixel along the singular-order dimension of the SVD-derived left singular vectors U. A pixel-wise clutter-energy ratio is computed to derive a spatially adaptive declutter weighting map, which is applied to the SVD-filtered flow signals. Results: UPBD was evaluated on multiple in vivo datasets. Quantitative assessments based on contrast-to-noise ratio (CNR) and contrast-to-tissue ratio (CTR) demonstrated significant improvements over conventional SVD filtering. For example, UPBD enhanced CTR from 7.3 dB to 21.7 dB in contrast-free pig kidney, 17.8 dB to 42.1 dB in contrast-enhanced pig kidney, 8.2 dB to 32.8 dB in human kidney, and -4.9 dB to 3.7 dB in 3D human liver. Conclusion: The proposed UPBD method effectively suppresses HCA while preserving blood flow signals with minimal extra computational cost and no need for extensive parameter tuning. Significance: UPBD serves as a lightweight, easily integrated post-processing method that enhances HCA suppression, enabling broader application of SVD-based ultrafast Doppler imaging.