Shear modulus imaging by direct visualization of propagating shear waves with phase-sensitive optical coherence tomography

We propose an integrated method combining low-frequency mechanics with optical imaging to map the shear modulus within the biological tissue. Induced shear wave propagating in tissue is tracked in space and time using phase-sensitive optical coherence tomography (PhS-OCT). Local estimates of the shear-wave speed obtained from tracking results can image the local shear modulus. A PhS-OCT system remotely records depth-resolved, dynamic mechanical waves at an equivalent frame rate of ∼47  kHz with the high spatial resolution. The proposed method was validated by examining tissue-mimicking phantoms made of agar and light scattering material. Results demonstrate that the shear wave imaging can accurately map the elastic moduli of these phantoms.