Asynchronous, semi-reverberant elastography

Area of Science:

• Biomedical Optics
• Medical Imaging
• Biophysics

Background:

• Optical coherence elastography (OCE) measures tissue elasticity, crucial for diagnosing pathologies like tumors, atherosclerosis, and ocular diseases.
• Wave-based elastography, including reverberant elastography, uses shear waves to determine tissue stiffness but often requires complex synchronization with imaging systems.
• Existing OCE methods face challenges in clinical adoption due to the need for precise synchronization between shear wave excitation and optical coherence tomography (OCT) imaging.

Purpose of the Study:

• To develop and demonstrate a method for recovering the complete harmonic shear wave field using a conventional, asynchronous, raster-scanning OCT system.
• To overcome the synchronization limitations of current OCE techniques, facilitating wider clinical translation.
• To enable sensitive elasticity measurements with reduced motion artifacts in real-time.

Main Methods:

• Developed a novel approach to model raster-scanning OCT as an amplitude modulation of the displacement field.
• Implemented a technique for complete recovery of the complex-valued shear wave field from only two B-scans.
• Utilized reverberant elastography principles adapted for asynchronous OCT systems.

Main Results:

• Successfully recovered the entire spatially and temporally coherent complex shear wave field.
• Reduced the time scale for motion sensitivity from minutes to tens of milliseconds.
• Achieved the first in vivo demonstration of reverberant elastography on a human subject using a conventional frame-rate, raster-scanning OCT system.

Conclusions:

• The presented method enables robust shear wave recovery in asynchronous OCT systems, overcoming previous synchronization barriers.
• This advancement significantly expands the potential for widespread clinical adoption of advanced elastography techniques.
• The findings represent a major step towards translating OCE for routine diagnostic applications.