Effect of stationary reverberations and clutter filtering in strain rate imaging

Stationary reverberations introduce a bias and an increased variance in velocity magnitude estimates based on Doppler ultrasound imaging. Clutter filtering is commonly used to remove the reverberations. For low velocities though, clutter filtering increases the variance and introduces a bias. The newly developed Strain Rate Imaging (SRI) technique is based on estimating the tissue velocity gradient. To study the effect of stationary reverberations and clutter filtering a the strain rate estimate the authors performed an experiment where RF-data from a dynamic in vitro model of myocardial tissue was obtained. Stationary reverberations were simulated and added to the RF-data at different signal-to-clutter ratios (SCR). The results showed that zero order clutter filtering only reduced the variance for SCR=0 dB. For higher SCR the variance increased. Similarly, clutter filtering reduced the fractional bias for SCR=0 and increased it for SCR above 10 dB