An ultrasound system for imaging a target is provided. The system includes a plurality of transducer elements; at least one transmitter configured to excite at least one of the transducer elements to emit ultrasound energy to the target; a plurality of samplers configured to sample echo signals received by at least some of the plurality of transducer elements, the echo signals comprising acoustic echoes received from the target responsive to the ultrasound energy; a coherence calculator configured to calculate a plurality of coherence values, each of the coherence values corresponding to a measure of similarity between at least two sample echo signals; an estimator configured to estimate a coherence contribution estimate, the coherence contribution estimate comprising an estimate of a contribution of at least one coherence model to the plurality of coherence values.