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GASTROINTESTINAL TISSUE ANALYSIS WITH NOVEL OPTICAL COHERENCE TOMOGRAPHY
Theethawat Thanawiboonchai
*1, Cheng-Yu Lee
2, Jing Zhang
2, Nathnael A. Woldehana
1, Gina Adrales
1, Xingde Li
21Surgery, Johns Hopkins University, Baltimore, MD; 2Johns Hopkins University, Baltimore, MD
Introduction: Esophageal and gastric cancers are common gastrointestinal (GI) malignancies. Early detection is essential, but current diagnostic methods, such as endoscopy, require procedural access and the need for sedation. These challenges emphasize the need for new, minimally invasive diagnostic technologies. We developed a dual-wavelength Optical Coherence Tomography (OCT) system (800 nm and 1300 nm) for improved imaging depth and resolution. This study examines the performance of this system on ex vivo gastric tissue, comparing OCT findings with histology.
Methods: Freshly excised normal human stomach samples were used to explore the imaging capabilities of OCT. Specimens were kept in phosphate-buffered saline at 4°C and imaged within an hour to preserve integrity. Samples were placed on a paraffin plate with a No. 0 cover glass to reduce back reflection, and Indian ink dots ensured consistent localization. Two custom OCT systems were employed: an 800 nm system with 2.5 µm axial and 8.4 µm lateral resolution, and a 1300 nm system with 9 µm axial and 20 µm lateral resolution. The 800 nm system scanned a 3 × 3 mm area at 30 fps in 8 seconds, while the 1300 nm system scanned at 50 fps in 5 seconds. Both systems produced 1024 × 2048 × 256 volumetric datasets. After imaging, tissues were formalin-fixed, paraffin-embedded, sectioned at 5 µm, and stained with H&E for comparison with OCT images.
Result: Figure 1 (A) to (D) are en face and corresponding B-frame images captured using two OCT systems. Figure 1 (E) and (F) illustrate histological slides of the corresponding cross-section, highlighting the mucosa, submucosa, and muscularis propria. The mucosa extends to a depth of 500 ?m, featuring surface gastric pits and deeper glandular structures. The 800 nm OCT system demonstrated outstanding resolution in visualizing the gastric pits, while the 1300 nm system excelled in imaging the submucosa. En face images from both wavelengths successfully resolved fine pit structures, highlighting their complementary imaging capabilities.
Conclusion: This study demonstrates the significant potential of OCT as a non-invasive, high-resolution imaging technique for gastrointestinal tissue. The clear correlation between OCT images and histological findings underscores its clinical applicability. Future advancements may include the adoption of portable OCT systems for endoscopic procedures. Capsule endoscope designs have been shown to enable stable circumferential scanning and high-quality 3D visualization. Combined with front-view cameras and laser ablation marking for precise localization, future developments will focus on distinguishing normal and diseased tissues and advancing in vivo human studies. These innovations position OCT as a powerful tool for diagnostics, surgical guidance, and therapeutic monitoring in gastrointestinal medicine and surgery.
Figure 1. Ex vivo imaging results from two OCT systems. (A) En face image acquired with the 800 nm OCT system. (B) Corresponding B-frame image from 800 nm OCT, with the location indicated by the red line. (C) En face image acquired with the 1300 nm OCT system. (D) Corresponding B-frame image from 1300 nm OCT, with the location indicated by the red line. (E) Histology slide from the corresponding imaging site with a 4× objective. (F) Histology slide from the corresponding imaging site with a 10× objective.
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