Following patient enrollment, surgical interventions were performed in accordance with standardized clinical protocols. During the operative procedure, the excised sentinel lymph nodes (SLNs) underwent specialized incubation processing. The detailed experimental protocol was conducted as follows:
1. Preparation of incubation solution The molecular probe was reconstituted in phosphate-buffered saline (PBS) to create incubation solutions with concentration gradients of 6.25, 12.5, 25, and 50 μg/mL. Solution preparation was performed at ambient temperature under light-protected conditions.
2. Ex vivo SLN tissue incubation Freshly excised SLN specimens were fully immersed in the prepared solutions for designated durations (1, 3, 5, 7, or 10 minutes). Subsequent processing included a 5-minute wash cycle with PBST buffer (0.05% Tween 20 in PBS) followed by blot-drying using absorbent filter paper.
3. NIR-II fluorescence imaging analysis Imaging acquisition was conducted using the Digital Precision Medicine (DPM) NIR-II system. Following initial system parameter calibration and spatial scaling, fluorescence signals were captured and quantitatively analyzed to determine SLN metastatic status through proprietary diagnostic algorithms.
4. Histopathological validation Final diagnostic confirmation was obtained through comprehensive histopathological examination conducted by certified pathologists.
