Tissue elasticity imaging based on combined autocorrelation method and 3-D tissue model

To obtain an accurate strain distribution under a large displacement, beyond ultrasonic wavelength, we propose a method of reconstructing the strain distribution by modifying the autocorrelation technique. We call this method the `combined autocorrelation method'. The method is capable of rapidly detecting strain in the phase domain processing without aliasing. We also attempt to reconstruct the elastic modulus distribution by solving the inverse problem based on a 3-D finite element tissue model. These methods were applied to obtaining strain and elastic modulus images of a tumor phantom and an extracted breast tissue including a cancer tumor. A tumor with a 10 mm diameter and with poor contrast in a B-mode image was clearly displayed as a region harder than the surrounding soft tissue in the strain and elastic modulus images. These results indicate that the proposed method is a promising means for diagnosing tumor.