Direct strain estimation in ultrasound elastography using a novel dynamic programming approach

Quasi-static elastography methods often calculate the displacement field from ultrasound data and calculate strain by performing spatial derivative of the displacement field. In this paper, a strain imaging technique called SHORTCUT is introduced in which the strain field is estimated directly from the RF data using a novel dynamic programming (DP) technique. The DP cost function is formulated in terms of strain and incorporates similarity of echo amplitudes and strain continuity into a cost function. This is in contrast to previous work wherein the cost function was formulated in terms of displacement and enforced displacement continuity. This approach has several advantages. First, a much smaller search range for the displacement derivative will cover a much larger search range of the displacement field. This will substantially reduce the computational complexity of DP. Second, the new framework substantially reduces the bias introduced by the displacement continuity constraint. And third, the strain is directly estimated from DP and no spatial derivation step is needed. Our results on phantom and in vivo patient data show that SHORTCUT substantially outperforms previous work.