Poroelastography: estimating and imaging the poroelastic properties of tissues

In the field of elastography, biological tissues are typically assumed to be purely linear elastic solids. However, several tissues including brain, cartilage and edematous soft tissues, have long been known to be poroelastic. The authors recently developed a method to estimate the local Poisson's ratio in linear elastic solids (see Ultrasound in Medicine and Biology, vol. 24, no. 8, p. 1183-99, 1998). In the current study the authors use the same method to measure the time-dependent effective Poisson's ratio in poroelastic materials. The resulting time-sequenced poroelastograms show the spatial distribution of the fluid within the solid at each time instant and give insight into the Poisson's ratio of the solid and its permeability to the fluid. Results were obtained from both finite-element simulations and experimental poroelastic phantoms.