A multi-scale algorithm for ultrasonic strain reconstruction under moderate compression

Since the waveform of an echo is more distorted under larger compression, elastography can be applied in cases where the compression is only a few percent. To reduce errors due to distortion of the echo waveform, a novel algorithm (i.e. the multi-scale correlation algorithm) for strain profile reconstruction is proposed in this article. The basic idea of this method is to simulate human vision: first, we locate the region of the target, and then match the detail within this region and make a comprehensive criterion. Based on this concept, three different approach algorithms are proposed and investigated: (1) the two-step method, (2) the multi-scale correlation algorithm, and (3) the extended multi-scale correlation algorithm. To evaluate the algorithms proposed in this work, a computer simulation model is used and a sequence of simulation experiments are performed. The correlating specificity is used as a criterion for evaluating the performance characteristics of the correlation estimation. The results show that the extended multi-scale correlation algorithm performs significantly better than the other two methods proposed in this article under moderate compression ratios. The extended multi-scale correlation algorithm is applicable to both small and moderate compression ratios. This novel algorithm may provide a useful tool for the clinical application of elastograms.