Detecting Solid Masses in Phantom Breast Using Mechanical Indentation

Palpation is an economical, safe and effective method to detect breast cancer among other expensive and sometimes limited diagnostic tools such as mammography and magnetic resonance imaging (MRI). To understand the mechanics of palpation, a rigid inclusion was embedded in a phantom gel to simulate the lesion. An array of indents using a rigid indenter was made over an assigned area of the phantom surface, while the applied load, F, was measured as a function of instantaneous indentation depth, w. When the local stress field interacted with a sufficiently shallow inclusion, the mechanical response F(w) yielded an augmented apparent stiffness C. A 2-dimensional spatial map of C shows the presence, depth, and geometry of the simulated lesion. A camcorder was used to capture the in-situ movement of the inclusion during indentation, which showed consistency with the finite element (FEA) prediction. Results provide preliminary confirmation that mechanical indentation is a good tool to complement existing imaging techniques and has the potential to guide design and fabrication of an automatic palpation device.