Video endoscopy remains the most common means of examining the upper gastrointestinal tract. However, white-light widefield imagery is limited in diagnostic sensitivity and specificity for conditions such as Barrett’s esophagus. To provide cross-sectional imaging that yields more accurate diagnosis, optical coherence tomography (OCT) has been implemented for upper GI screening and diagnosis in several form factors, such as inflatable balloons and tethered capsules.
We now present an alternative configuration for esophageal OCT. Our OCT probe is contained within an articulating paddle that attaches to the end of an upper GI endoscope via flexible cuff. This arrangement allows regions of interest to be visually identified by the physician operating the endoscope and targeted for OCT imaging by application of the paddle.
The probe housing was 3D printed using biocompatible dental resin. The flexible cuff was also 3D printed using a silicone-based resin to allow a tight fit to the endoscope. The optical probe was a rotating fiber-optic design, consisting of a gradient-index lens and prism on the distal end, wound steel torque coil, a polymer sheath, and a fiber-optic rotary junction. The OCT system was a spectral domain configuration with custom spectrometer operating at 20,000 A-lines per second. The illumination source was a superluminescent diode centered at 1310 nm.
A clinical pilot study at the University of North Carolina Endoscopy Center is scheduled to begin imminently.
Optical imaging techniques generally offer shallow penetration depths due to high scattering in biological tissue. We have recently developed dual-axis optical coherence tomography (DA-OCT) for interferometric imaging at extended depths. By illuminating and collecting at oblique angles, multiply forward scattered photons from deeper penetration depths were favorably detected. A Monte Carlo study demonstrated a >12-fold increase in signal-to-background ratio (SBR) in skin tissue at 1 mm depth by DA-OCT. A 1300 nm DA-OCT system was designed and constructed, offering an imaging depth of up to 2 mm in skin tissue