Strain Tensor Elastography: 2D and 3D Visualizations

Abstract

Elastography measures the elastic properties of soft tissues using principally ultrasound (US) or magnetic resonance (MR) signals. The elastic behavior of tissues can be analyzed with tensor signal processing. Different approaches have been developed to estimate and image the elastic properties in the tissue. In ultrasound elastography, the estimation of the displacement and strain fields is mostly based on measures computed from the Radio Frequency signals, such as time-domain cross-correlation. We propose to estimate the displacement field from two consecutive B-mode images using a multiscale optical flow method. The tensor strain field can then be plotted as ellipsoids, visualizing in a single image the standard scalar parameters that are usually represented separately. This technique can offer physicians the possibility of extracting new discriminant and useful parameters related to the elastic behavior of tissues. Although clinical validation is still needed, our experiments from finite element and ultrasound simulations display consistent and reliable results.