Endoscopic en-face optical coherence tomography and fluorescence imaging using correlation-based probe tracking

TL;DR

This paper presents a method to create a 2D endoscopic imaging system combining OCT and fluorescence imaging using a 1D probe with motion correction, enabling real-time en-face imaging despite probe movement.

Contribution

It introduces a correlation-based motion correction technique that transforms a 1D scanning probe into a 2D imaging system for endoscopic OCT and fluorescence imaging.

Findings

Real-time en-face OCT and fluorescence imaging achieved.

Motion correction handles out-of-plane speeds up to 4 mm/s.

Lateral resolution of approximately 20 micrometers.

Abstract

Forward-viewing endoscopic optical coherence tomography (OCT) provides 3D imaging in vivo, and can be combined with widefield fluorescence imaging by use of a double-clad fiber. However, it is technically challenging to build a high-performance miniaturized 2D scanning system with a large field-of-view. In this paper we demonstrate how a 1D scanning probe, which produces cross-sectional OCT images (B-scans) and 1D fluorescence T-scans, can be transformed into a 2D scanning probe by manual scanning along the second axis. OCT volumes are assembled from the B-scans using speckle decorrelation measurements to estimate the out-of-plane motion along the manual scan direction. Motion within the plane of the B-scans is corrected using image registration by normalized cross correlation. En-face OCT slices and fluorescence images, corrected for probe motion in 3D, can be displayed in real-time during the scan. For a B-scan frame rate of 250 Hz, and an OCT lateral resolution of approximately 20 micrometers, the approach can handle out-of-plane motion at speeds of up to 4 mm/s.