Spectroscopic Intravascular OCT

Overview

Spectroscopic intravascular OCT (S-OCT) extends conventional OCT by extracting wavelength-dependent tissue optical properties from the broadband interference signal. This enables quantitative characterization of coronary artery tissue composition — distinguishing lipid-rich necrotic cores from fibrous caps and calcified regions — without the need for additional imaging modalities.

Technical Approach

The system is built on a swept-source OCT platform operating at 1310 nm center wavelength with 100 nm bandwidth. Key innovations include:

Inverse algorithm design. We developed a Tikhonov-regularized spectral fitting framework that extracts depth-resolved scattering and absorption coefficients from the OCT signal. The algorithm handles the ill-posed nature of the inverse problem through joint regularization across wavelengths, exploiting the spectral smoothness of biological chromophores as a physical prior.

Polarization-sensitive extension. By incorporating Jones matrix analysis of the polarization state evolution through the catheter and tissue, we add birefringence as a third contrast mechanism alongside scattering and absorption. This is particularly valuable for characterizing collagen organization in fibrous caps.

Real-time processing pipeline. The computational framework is designed for eventual real-time operation during catheterization procedures, using GPU-accelerated spectral processing and pre-computed lookup tables for the inverse solver.

Current Status

The inverse algorithm has been validated on tissue-mimicking phantoms with known optical properties, achieving relative reconstruction error below 5%. We are currently preparing for ex vivo validation on human coronary artery specimens, with in vivo animal studies planned for late 2026.

Impact

Reliable, quantitative tissue characterization during cardiac catheterization could transform the management of coronary artery disease. Current clinical OCT provides structural images but cannot quantify tissue composition — clinicians must infer plaque vulnerability from morphological features alone. S-OCT would provide direct biochemical contrast, enabling more accurate identification of vulnerable plaques and better-informed treatment decisions.