Elasticity imaging of soft tissue with contact impedance method was performed to quantify medical palpation. Frequency changes of piezoelectric vibrator in contact with soft tissue depends on the elastic modulus of materials. This technique is called “Contact Impedance Method”. Frequency changes of tumor model made by silicone rubber were measured with this system. It was shown that we could detect the tumor under normal tissue that couldn't be detected by stress-strain curve with this method. In order to clarify the mechanism of tumor detection, we calculated the equivalent mass area that decreases frequency. These results suggested a possibility of quantification of medical palpation with elastic modulus imaging of large area. The method can be used for quantitative diagnosing method of disease state.
