Coherence-based quantification of acoustic clutter sources in medical ultrasound | CU Experts

The relative contributions of aberration and incoherent noise sources, such as diffuse reverberation and thermal noise, to image quality in medical ultrasound are not well understood. We present a theoretical framework to predict losses in the correlation of ultrasonic backscatter, i.e., spatial coherence, and imaging contrast in response to combinations of incoherent noise and aberration levels. This framework is based on estimating the beamformer gain and channel SNR, using measurements of spatial coherence. A method to separate the contributions of incoherent noise and aberration in the spatial coherence domain is also explored and applied to predict losses in contrast. Results indicate excellent agreement between theory and simulations for beamformer gain and expected contrast loss. Coherence-predicted contrast loss and measured contrast loss in aberration differ by less than 1.5dB on average, for a −20 dB contrast target and aberrators with RMS time delay errors and spatial autocorrelation profiles similar to those measured in vivo. Results also indicate that the contribution of aberration to contrast loss varies with channel SNR, peaking around 0 dB SNR. This framework shows promise to facilitate novel, targeted clutter reduction strategies by providing a means to isolate and estimate the contributions of correlated and uncorrelated noise.

VIVO