Enhanced phase extraction in optical coherence elastography using discrete cosine transform for localized tissue characterization

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Abstract We develop a novel enhanced laser-based elastography technique that utilizes an optical coherence tomography (OCT) imaging system. This enhancement combines the capabilities of OCT with an advanced phase extraction technique, aiming to increase the precision of biomechanical measurements in soft tissues. Our approach utilizes the discrete cosine transform (DCT) for phase extraction, overcoming the limitations of vector-based methods in handling complex geometries and large displacements. Unlike fast Fourier transform-based unwrapping, DCT ensures thar the result is artifact-free. This advancement refines spatial detail in optical coherence elastography (OCE), enabling accurate mapping of tissue elasticity and structural variations. By eliminating windowing constraints, our method offers a faster, more robust solution for biomechanical diagnostics. In this study, we introduce a micro-elastography system that utilizes a 4 ohm speaker as a mechanical excitation source to apply controlled, quasi-static compressions. This system, combined with a high-speed, 100 kHz swept-source OCT laser, enables rapid data acquisition and straightforward phase-to-strain conversion. Our findings demonstrate the system’s capability of providing accurate strain mapping across a range of samples, delivering reliable elastic information despite the challenges posed by non-linear and non-uniform tissue boundaries. This study showcases the potential of DCT-based OCE to enhance clinical diagnostics and improve the characterization of diseased and tumor boundaries in soft tissues.