Stress field calculation for quantitative ultrasound elastography via integration of force sensors

Most current elastography methods remain qualitative or display only strain information due to the inexact internal stress distribution. A more accurate result may be obtained by employing force sensors to gauge the applied vertical compression force on skin surface through the ultrasound transducer. A computationally efficient superposition algorithm based on Love´s closed-form equation (SLE) is presented. It performs analytical calculation of the 3D dynamic stress field inside a soft tissue phantom with non-free boundary conditions under a non-uniformly stressed rectangular linear array transducer, using the pressure on each element of the contact surface. The validity of the SLE method was tested by comparison to the stress field calculated with Finite Element Analysis (FEA). For the region of interest (directly underneath the ultrasound transducer), the SLE provides a sufficiently precise solution and can be exploited for absolute Young´s modulus reconstruction in real time.