Filter based spatial compounding for strain imaging
Ultrasound elastography is the technique of obtaining tissue relative stiffness information, which plays an important role in early diagnosis. Ultrasonic wave interference produces local fluctuations in both phase and envelope, known as speckle. Compounding reduces speckle by averaging envelope detected data from several decorrelated looks and may also be used to improve motion estimates by averaging the estimate from decorrelated looks. In this paper, we propose filter based spatial compounded strain imaging, which uses a filter band to create multiple looks to produce a compounded motion estimate. In conventional frequency compounding, the filters are applied in the axial direction, whereas in this case, they are applied in the lateral direction to create decorrelation between sub-bands. The effect of filter based receive frequency compounding is investigated through phantom experiments, which confirms the reduction in strain image artifact is accomplished with no sacrifice of real-time ultrasonic imaging as well as a measurable improvement in SNRe and CNRe.