Surface-Wave-Induced Photoacoustic Elastography in the Feasibility Study of Tissue Biomechanical Properties

Understanding the mechanical properties of biological tissue is crucial in comprehending pathophysiological conditions, facilitating disease diagnosis, and advancing treatment options. It serves as a diagnostic biomarker for various life-threatening diseases (including cancer). In this article, we have demonstrated a low-cost external vibration-based photoacoustic elastography technique that enables the characterization of tissue stiffness and the monitoring of thermal coagulation through the mapping of biomechanical properties. To substantiate the proposed technique, we experimented on agar phantoms with different concentrations (~2%, 3%, and 4%) and coagulated chicken tissues. For each experiment, displacement of the tissue under external vibration is evaluated to gain the knowledge about stiffness or hardness of the tissue material. The proposed method demonstrated its potential to differentiate the elasticity of tissue-mimicking agar phantoms with different concentrations. In the case of coagulated chicken tissue, a sharp distinction in displacement reduction is observed with a longer tissue coagulation time. An increment in elasticity caused by higher tissue coagulation time is clearly reflected in displacement changes. Therefore, our proposed method enables us to monitor tissue coagulation studies based on biomechanical property characterization. With the inclusion of real-time processing from photoacoustic tomography (PAT), this elastography technique could be a great asset for measuring tissue stiffness in the fields of dermatology, oncology, rehabilitation, and orthopedics.