Quantitative nonlinear shear modulus mapping using freehand scanning

Nonlinear shear modulus (NLSM) can potentially distinguish between benign and malignant breast lesions. Although studies have demonstrated the potentials of quantitative NLSM mapping techniques, the prospect of using these techniques in clinic is limited due to the challenges they pose during data acquisition. NLSM imaging requires large tissue deformation and measurement of both tissue strain and shear wave speed involving two different types of elastography techniques. It is challenging to acquire such data at multiple compression levels while maintaining the speckle correlation within a plane. Additionally, deformation induced from free-hand scanning is compound in nature, containing both compression and shear components, which is not well-modeled. In this work, we developed a freehand NLSM imaging technique that overcomes these challenges. First, we utilized a recently developed analytic model that estimates NLSM at lower levels of compound motion. Second, we developed acquisition sequences that allow rapid acquisition of strain and shear wave elastographic data.