Mapping Tactile Imaging Information: Parameter Estimation and Deformable Registration

Medical Tactile Imaging uses an array of pressure sensors mounted on a rigid scanhead to record the surface pressures that result when the scanhead is pressed into biological tissue. The resulting tactile data quantifies palpation, and contains information on the stiffness of the underlying tissue as well as the geometric distribution of the stiffness. Tactile imaging shows promise for clinical use in breast palpation and in assessing tissue properties in organs such as the liver. To date, tactile information has been used to estimate tissue geometry but not stiffness. We develop a linear algorithm to estimate the salient tissue parameters from a simple model of a solid lesion attached to the substrate of soft tissue. The parameters of interest are the background stiffness and thickness, and the stiffness and diameter of a round lesion. The algorithm is developed using finite element models, and results obtained on physical models show errors of 5.4% in estimating lesion modulus. This work was extended to the case of a solid lesion floating in soft tissue,