Compact dual-channel visible-light fluorescence endoscope for real-time molecular imaging: system design and...

Intraoperative identification of early ectopic pregnancy tissue remains challenging because chorionic villi often exhibit low visual contrast from surrounding inflamed or hemorrhagic tissue under conventional white-light endoscopy. To address this limitation, we developed a compact dual-channel visible-light fluorescence endoscopic imaging system configured as a modular 10 mm rigid endoscopic platform compatible with standard 10 mm laparoscopic workflows for real-time dual-channel acquisition and fusion. The system integrates a narrow-band 490 nm LED excitation source with a customized long-pass dichroic beam-splitting module to simultaneously acquire targeted fluorescence at ∼515 nm and diffuse reflectance at 490 nm. The two image streams are synchronized and fused to provide real-time molecular-anatomical visualization. Using a FITC-labeled anti-β-hCG antibody as a model targeted probe, we evaluated the system on 14 ex vivo human ectopic pregnancy specimens. The system achieved high-contrast visualization of villous tissue, with a target-to-background ratio of 4.17 ± 0.59. Mean fluorescence intensity was significantly higher in villous tissue than in adjacent non-villous tissue (115.76 ± 21.31 vs. 28.29 ± 6.74, P < 0.001). High-fluorescence regions showed close spatial correspondence with the pathological ground truth confirmed by H&E and immunohistochemistry. These findings demonstrate the feasibility of combining a compact visible-light dual-channel endoscopic platform with a targeted fluorescent probe for ex vivo molecular imaging of ectopic pregnancy tissue, and support future studies on translational optimization, safety qualification, and in vivo validation.