NOISE-REDUCTION IN ELASTOGRAMS USING TEMPORAL STRETCHING WITH MULTICOMPRESSION AVERAGING

Elastography uses estimates of the time delay (obtained by cross-corre lation) to compute strain estimates in tissue due to quasistatic compr ession, Because the time delay estimates do not generally occur at the sampling intervals, the location of the cross-correlation peak does n ot give an accurate estimate of the time delay, Sampling errors in the time-delay estimate are reduced using signal interpolation techniques to obtain subsample time-delay estimates, Distortions of the echo sig nals due to tissue compression introduce correlation artifacts in the elastogram. These artifacts are reduced by a combination of small comp ressions and temporal stretching of the postcompression signal, Random noise effects in the resulting elastograms are reduced by averaging s everal elastograms, obtained from successive small compressions (assum ing that the errors are uncorrelated). Multicompression averaging with temporal stretching is shown to increase the signal-to-noise ratio in the elastogram by an order of magnitude, without sacrificing sensitiv ity, resolution or dynamic range, The strain filter concept is extende d in this article to theoretically characterize the performance of mul ticompression averaging with temporal stretching. Copyright (C) 1996 W orld Federation for Ultrasound in Medicine & Biology