Multi-frame elastography using a handheld force-controlled ultrasound probe.
We propose a new method for strain field estimation in quasi-static ultrasound elastography based on matching RF data frames of compressed tissues. The method benefits from using a handheld force-controlled ultrasound probe, which provides the contact force magnitude and therefore improves repeatability of displacement field estimation. The displacement field is estimated in a two-phase manner using triplets of RF data frames consisting of a pre-compression image and two post-compression images obtained with lower and higher compression ratios. First, a reliable displacement field estimate is calculated for the first post-compression frame. Second, we use this displacement estimate to warp the second post-compression frame while using linear elasticity to obtain an initial approximation. Final displacement estimation is refined using the warped image. The two-phase displacement estimation allows for higher compression ratios, thus increasing the practical resolution of the strain estimates. The strain field is computed from a displacement field using a smoothness- regularized energy functional, which takes into consideration local displacement estimation quality. The minimization is performed using an efficient primal-dual hybrid gradient algorithm, which can leverage the architecture of a graphical processing unit. The method is quantitatively evaluated using finite element simulations. We compute strain estimates for tissue-mimicking phantoms with known elastic properties and finally perform a qualitative validation using in vivo patient data.
Andrey
A
Kuzmin
Aaron M
AM
Zakrzewski
Brian W
BW
Anthony
Victor
V
Lempitsky
D000465:Algorithms; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D015203:Reproducibility of Results