The subband processing was applied to ultrasound strain imaging to reduce strain noise. The echo radio frequency signal was separated into several frequency bands by subband filters. The strains of each subband were estimated and then all sub strain images were averaged to produce a compounded strain image. This approach was tested in a commercial strain imaging system by scanning a tissue-mimicking phantom. The experimental results demonstrated that the elastographic signal-to-noise ratio and elastographic contrast-to-noise ratio of strain image can be increased up to 18% and 42% by using subband processing, respectively.
