Fine elasticity imaging utilizing the iterative RF-echo phasematching method

摘要

To non-invasively quantify elasticity of soft tissue, wenpreviously developed the iterative two-dimensional (2-D) rf-echo phasenmatching method for accurately measuring a 2-D displacement vector fieldngenerated in vivo in soft tissue during acquisition of two successivenrf-echo data frames. We also developed a stable method for uniquelynreconstructing a shear modulus distribution using strains derived fromnthe measurement data. However, as in our measurement method andisplacement is determined by using the phase characteristics of thenfinite local echo data as the index to iteratively search for thencorresponding local data, change of the local phase characteristics duento tissue deformation deteriorates the accuracy of the determination.nThus, we improve the previous method such that, in principle, thendisplacement can be determined using an infinitesimal phasencharacteristics. That is, we incorporate an effective mechanism into thenprevious iterative phase matching scheme: the local size is madensuitably smaller during the iterative phase matching. The demonstratednability of measurement and reconstruction in simulation, and experimentsnon in vitro in pork rib and in vivo in breast tissue, shows thisnrefinement allows not only better spatial resolution of the shearnmodulus image but also improved accuracy, and indicates that thenimproved method has a high potential to be applied for various softntissues