Ultrasound Imaging, harmonic imaging, coherence-based beamforming, theory
Abstract:
SLSC imaging has been combined with harmonic imaging to combine the benefits of SLSC beamforming and harmonic imaging, but the theory describing its performance was never mathematically derived, which limits understanding of nuances observed when implemented experimentally. The objective of this work is to derive and evaluate coherence theory for harmonic SLSC beamforming of ultrasound images. The spatial coherence of harmonic ultrasound channel data as a function of receive element separation was derived by exchanging the role of transmit and receive apertures relative to fundamental SLSC beamforming theory. Theoretical results were compared with experimental results and the mean spatial coherence function within a hyperechoic region supports the theoretically derived similarity between the harmonic spatial coherence function and a fundamental spatial coherence function. These results demonstrate the potential of our new harmonic SLSC theoretical derivation to explain the vastly different performance of harmonic spatial coherence imaging when applied to different in vivo organs (e.g., heart, liver, fetus, breast).
