Optical Coherence Elastography with Needle-based Piezoelectric-driven Probe

Abstract

Biomechanical properties can give key information about the health, structure, and function of tissues. In particular, information about biomechanical properties of cardiac tissue could be useful in determining tissue damage due to ischemia. In this study, we use a piezoelectric-driven blunt needle elastography probe to create longitudinal shear waves, allowing us to determine cardiac tissue biomechanical properties. A lensed fiber was connected to a 200kHz swept-source optical coherence tomography (SSOCT) system. The fiber was inserted through the lumen of a PZT ring and then through a blunt needle which was attached to the PZT. The blunt needle was used to maintain contact between the tissue and the probe, while the lensed fiber was recessed within the needle for imaging. The probe was used to gather data from 2% and 2.5% agar phantoms as well as a mouse heart. The PZT was excited at 1KHz to induce longitudinal shear waves through the samples. M-mode images were acquired simultaneously from the probe setup(200kHz) at the center of excitation for all samples. To verify the generation of longitudinal shear wave, MB-mode images were acquired simultaneously from another 30 kHz SSOCT setup. To analyze the wave speed, spatiotemporal maps of wave propagation were created and speed was determined by linear fitting. The 2% and 2.5% agar phantoms sample exhibited wave speeds of 1.93 m/s and 2.47 m/s, respectively. For the mouse cardiac tissue, the wave speed was determined to be 1.98 m/s. Our results show that this probe can effectively measure longitudinal shear wave propagation and may be suitable for clinical applications.

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Harshdeep Singh Chawla
1Department of Biomedical Engineering, University of Houston
United States

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