Elastography for breast cancer diagnosis using radiation force: system development and performance evaluation

The use of impulsive acoustic radiation force for strain imaging was investigated. A focused ultrasound transducer was used to apply localized radiation force to a small volume of tissue mimic (100 mm3) for durations of 8 ms. A conventional real-time ultrasound imaging probe was used to obtain echo signals. The resulting strains were mapped using ultrasound correlation-based methods. The instantaneous strain immediately following cessation of the radiation force was observed at depth within homogeneous gels and within stiff inclusions, and was seen to vary approximately linearly with Young's modulus of the material. The highly localized and transient strain that is produced may permit the sensing of variations in tissue elastic properties that are difficult to detect with conventional elastography because of greater independence from boundary conditions. For example, the characteristic, bi-directional, high strain artefacts attributable to stress concentration, often seen with static elastography at tissue-inclusion interfaces, do not appear using the transient radiation force strain imaging technique.