Ultrasound Elastography Using Empirical Mode Decomposition Analysis

Ultrasound elastography is a non invasive method which images the elasticity of soft tissues. to make an image, pre and after asmall compression, ultrasound radio frequency (rf) signals are acquired and the time delays between them are estimated. the firstdifferentiation of displacement estimations is called elastogram. in this study, we are going to make an elastogram using the processingmethod named empirical mode decomposition (emd). emd is an analytic technique which decomposes a complicated signal to acollection of simple signals called intrinsic mode functions (imfs). the idea of paper is using these imfs instead of primary rf signals.to implement the algorithms two different datasets selected. the first one was data from a sandwich structure of normal and cookedtissue. the second dataset consisted of around 180 frames acquired from a malignant breast tumor. for displacement estimating, twodifferent methods, cross correlation and wavelet transform, were used too and for evaluating the quality, two conventional parameters,signal to noise ratio (snr) and contrast to noise ratio (cnr) calculated for each image. results show that in both methods after usingemd the quality improves. in first dataset and cross correlation technique cnr and snr improve about 16 db and 9 db respectively. insame dataset by using wavelet technique, the parameters show 14 db and 10 db improvement respectively. in second dataset (breasttumor data) cnr and snr in cross correlation method improve 18 db and 7 db and in wavelet technique improve 17 db and 6 dbrespectively.