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Shear modulus imaging based on full-field laser speckle contrast analysis for improved spatial resolution

Shear wave elastography, often based on ultrasound imaging, has been used to provide mechanical information of the imaged biological tissue for assisting pathologic diagnosis. To improve the sensitivity and spatial resolution of shear wave imaging, several optical imaging modalities have been investigated and implemented. In this study, laser speckle contrast imaging (LSCI) is used for detecting shear wave propagation in a tissue-mimicking phantom. Shear wave is induced by acoustic radiation force generated using a single element focused ultrasound transducer, driven by an ultrasonic burst with 100 μs duration. This imaging technique has shown good accuracy in estimating the shear wave velocity, which is justified by a commercial ultrasound system, with the deviation found to be less than 6% for soft and hard phantoms. Furthermore, this imaging system has exhibit a good sensitivity for detecting small shear wave displacement (approximately tens of nanometer), as well as distinguish small variation in phantom stiffness. With improvement in imaging sensitivity and spatial resolution (315 μm achieved in this study), LSCI has potential for providing detailed elasticity distribution analysis.