Feasibility of isosulfan blue in sentinel lymph node visualization for gastric cancer.

Objectives: This study aimed to investigate the feasibility of isosulfan blue (IB) for sentinel lymph node (SLN) visualization in a mouse model of gastric cancer (GC). Methods: For ectopic gastric tumor implantation, the right footpads of nude mice (tumor group) were inoculated with AGS-luciferase (AGS-Luc) cells, while the left footpads (normal group) served as controls. When tumor volume in footpad reached approximately 250 mm3, 1% IB was injected peritumorally. For orthotopic gastric tumor, AGS-Luc cells were administered into the subserous layer. When metastatic SLN was observed by in vivo imaging, 1% IB was injected within the subserous layer in nude mice. Results: The mean staining time of popliteal lymph nodes (LNs) were 21.48 ± 10.41 s [95% CI: 10.24-32.47] and 33.30 ± 16.79 s [95% CI: 12.23-52.34] in the tumor and normal groups, respectively. The mean washout time of popliteal LNs were 79.39 ± 21.95 min [95% CI: 60.26-102.1] and 85.24 ± 16.44 min [95% CI: 70.17-109.1] in the tumor and normal groups, respectively. In orthotopic gastric tumor model, SLNs could be observed with naked eye under room lighting after IB injection, and the mean staining time of SLNs was 104.0 ± 23.34 s [95% CI: 76.23-137.3], and the detection rate was 60%. For metastatic LNs, ectopic and orthotopic tumors were confirmed by hematoxylin and eosin staining. Conclusions: IB is feasible and effective for lymphatic mapping. The SLN concept using IB is feasible in mice and potentially translatable to GC, pending clinical validation.