High-intensity-focused ultrasound and phase-sensitive optical coherence tomography for high resolution surface acoustic wave elastography

Elastography has the ability of quantitatively evaluating the mechanical properties of soft tissue, thus is helpful for diagnosis and treatment monitoring for many diseases, e.g. skin diseases. Surface acoustic waves (SAWs) have been proven to be a noninvasive, non-destructive method for accurate characterization of tissue elastic properties. Current surface acoustic wave elastography using high energy laser pulse or mechanical shaker still have some problems. In order to improve SAW elastography in medical application, a new technique was proposed in this paper, which combines high intensity focused ultrasound (HIFU) as a SAWs impulse inducer and PhS-OCT as a SAWs detector. 2% agar-agar phantom and ex-vivo porcine skin were tested. The data were processed by a new algorithm based on the Fourier analysis. The results show that the proposed method has the capability of quantifying the elastic properties
of soft tissue mimicking materials. The lateral resolution of the elastogram has been significantly improved and the different layers in heterogeneous material could also been distinguished. Our improved technique of SAW elastography has a large potential to be widely applied in clinical use for skin disease diagnosis and treatment monitoring.