Figure 1 |.

Overview of the procedure for estimation of solid stress in tumors. (Top left) Examples of clinically relevant tumor models are developed via orthotopic implantation of cancer cells into the desired organs (see Table 2 for details on tumor models). (Steps 1–5) Solid stress is released and the stress-induced deformation is obtained via three different methods: the planar-cut method, in which solid stress is released by a planar cut at the plane of interest; the slicing method, in which the stress is released by cutting the tumor in a thin slice; and the needle-biopsy method, in which the stress is released by punching a cylindrical void into the tissue of interest. (Steps 7 and 8) The stress-induced deformation is imaged in 3D by high-resolution ultrasound or optical modalities such as optical coherence tomography (OCT) techniques. (Step 6) The material properties, such as Young’s modulus, are obtained at the microscale via atomic force microscopy, and at the macroscale by the unconfined compression test. Recently developed optical methods, such as laser speckle rheology¹⁶ and Brillouin scattering¹⁵ can also be used to provide a 2D map of stiffness in the plane of the cut. (Step 9) In the cases of the planar-cut and needle-biopsy methods, the stress-induced deformation and material properties are incorporated into a finite-element model to estimate the solid-stress component that is fully released. In the case of the slicing method, the area expansion of the slice is considered to be a bulk measure of the in-plane solid stresses. Parts of the figure are adapted from ref. 9, Springer Nature.