Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography

Area of Science:

• Biomedical Optics
• Medical Imaging
• Fluid Dynamics

Background:

• Optical coherence tomography (OCT) and optical coherence microscopy (OCM) measure axial blood flow using Doppler shifts.
• Current methods struggle with measuring lateral blood flow, which is perpendicular to the optical axis in many tissues.
• Existing techniques for lateral flow measurement are limited to simplified optical systems.

Purpose of the Study:

• To develop a generalized model for analyzing OCT/OCM system parameters influencing Doppler spectra.
• To establish a framework for quantitatively measuring both axial and lateral flow velocity components.
• To present an optimized protocol and algorithm for accurate flow reconstruction in OCT/OCM.

Main Methods:

• Developed a generalized model to analyze the impact of light source spectrum, numerical aperture, and beam geometry on Doppler spectra.
• Derived a framework relating Doppler frequency mean and variance to axial and lateral flow velocities.
• Designed an optimized acquisition protocol and reconstruction algorithm for quantitative flow measurement.

Main Results:

• The generalized model successfully relates OCT/OCM system parameters to Doppler spectral characteristics.
• The developed framework enables the separation and quantification of both axial and lateral flow velocities.
• Validated the approach by quantitatively measuring flow in a capillary using extended focus OCM and OCT.

Conclusions:

• The presented model and algorithm provide a robust method for quantitative lateral and axial flow measurement using OCT/OCM.
• This advancement overcomes limitations of previous methods, enabling broader applications in biological tissue analysis.
• The validated approach offers precise blood flow quantification critical for various biomedical applications.