Chirp-Coded Pulse Excitation for Ultrasound Elasticity Imaging

We first designed two chirp-coded excitation/ compression schemes which were applied to ultrasound elasticity imaging in simulation method using Field II. The simulation results demonstrate that in low echo-signal-to-noise ratio (eSNR) conditions, the performance of chirp-coded pulse for elasticity imaging is much better than the conventional short pulse, and indicate that elastographic signal-to-noise ratio (SNRe) of strain images for chirp-coded pulse is a function of attenuation, electronic noise, applied strain, pulse length, compression filter and depth. Comparing the effects of two chirp-coded excitation/compression schemes on strain imaging, we demonstrate that under the conditions of low eSNR, the first scheme, the combination of chirp excitation pulse with window and matched compression filter, is suitable to be used in low attenuation situations, and the second scheme, the combination of chirp excitation pulse without window and mismatched compression filter, is fit to be used in high attenuation situations. Finally, we applied the second chirp-coded scheme to a real-time freehand ultrasound strain imaging system and phantom experimental results are consistent with that in simulation method.