Esophageal OCT Imaging Using a Paddle Probe Externally Attached to Endoscope

Honeycomb effect elimination in differential phase fiber-bundle-based endoscopy

Fiber-bundle-based endoscopy, with its ultrathin probe and micrometer-level resolution, has become a widely adopted imaging modality for in vivo imaging. However, the fiber bundles introduce a significant honeycomb effect, primarily due to the multi-core structure and crosstalk of adjacent fiber cores, which superposes the honeycomb pattern image on the original image. To tackle this issue, we propose an iterative-free spatial pixel shifting (SPS) algorithm, designed to suppress the honeycomb effect and enhance real-time imaging performance. The process involves the creation of three additional sub-images by shifting the original image by one pixel at 0, 45, and 90 degree angles. These four sub-images are then used to compute differential maps in the x and y directions. By performing spiral integration on these differential maps, we reconstruct a honeycomb-free image with improved details. Our simulations and experimental results, conducted on a self-built fiber bundle-based endoscopy system, demonstrate the effectiveness of the SPS algorithm. SPS significantly improves the image quality of reflective objects and unlabeled transparent scattered objects, laying a solid foundation for biomedical endoscopic applications.

Diagnosis of Skin Burn-Induced Colon Circulatory Disorders Using Optical Coherence Tomography Angiography and Laser Doppler Flowmetry (Experimental Study)

The condition of gastrointestinal tract determines in many respects the regenerative capacity and the risk of complications in patients with extensive skin burns. However, the mechanism of developing vascular dysfunction in the colon in the burned individuals has so far been poorly studied. The aim of the investigation is to study intramural circulatory disorders of the colon using optical coherence tomography angiography (OCTA) and laser Doppler flowmetry (LDF) in different time periods after modeling a thermal burn.

Materials and Methods

A deep thermal skin burn was induced on the area covering 10% of the body surface of Wistar rats (n=15). The blood flow of the colon wall was continuously monitored for 15 min before and 45 min after the burn using OCTA and LDF. The colon wall was again studied on days 7 and 14 using the same OCTA and LDF techniques. At each time point (45 min, day 7 and 14), 5 animals were withdrawn from the experiment, the colon wall was taken for histological study. The colon wall samples from three control rats without thermal skin burns were also histologically investigated.

Results

During 45 min after the induction of the thermal burn, the in vivo OCTA and LDF techniques registered changes in intramural blood flow in the form of dropping of some arterioles and capillaries out of the general blood flow with concurrent activation of vascular shunts as a compensatory mechanism. Histologically, a marked edema of the submucosa, erythrocyte aggregation, and stasis in the capillary network were observed in this period. According to the OCTA and LDF data, the microcirculatory disorders in the colon were partially resolved by day 7, and by day 14 the analyzed indicators returned to the initial level. The data of the histological evaluation have shown that on day 7 after the burn induction, submucosal edema was absent, however, the signs of microcirculatory disorder and inflammatory changes remained. On day 14, the pathological changes in the tissues were not observed.

Conclusion

The OCTA and LDF methods allowed us to establish experimentally that during the first 45 min thermal burn causes considerable disturbances of the blood flow in the colon wall, which normalizes only by day 14 if no therapy is administered. The obtained data on the mechanism of circulatory disorder development in the colon may become a basis for choosing therapy directed to prevention of intestine dysfunction in people with burns.

Next-generation endoscopic probe for detection of esophageal dysplasia using combined OCT and angle-resolved low-coherence interferometry

Angle-resolved low-coherence interferometry (a/LCI) is an optical technique that enables depth-specific measurements of nuclear morphology, with applications to detecting epithelial cancers in various organs. Previous a/LCI setups have been limited by costly fiber-optic components and large footprints. Here, we present a novel a/LCI instrument incorporating a channel for optical coherence tomography (OCT) to provide real-time image guidance. We showcase the system's capabilities by acquiring imaging data from in vivo Barrett's esophagus patients. The main innovation in this geometry lies in implementing a pathlength-matched single-mode fiber array, offering substantial cost savings while preserving signal fidelity. A further innovation is the introduction of a specialized side-viewing probe tailored for esophageal imaging, featuring miniature optics housed in a custom 3D-printed enclosure attached to the tip of the endoscope. The integration of OCT guidance enhances the precision of tissue targeting by providing real-time morphology imaging. This novel device represents a significant advancement in clinical translation of an enhanced screening approach for esophageal precancer, paving the way for more effective early-stage detection and intervention strategies.