Enhancing remanent magnetization of injectable hydrogels improves realtime transluminal localization of tumor in hollow soft viscera

The accuracy of intraoperative localization of tumors undetectable under optical visualization determines surgical quality and survival outcomes in gastrointestinal cancers. Current approaches, however, remain constrained by suboptimal spatial resolution and low procedural efficiency. Additionally, conventional electromagnetic localization techniques based on image registration face challenges in soft tissue deformation scenarios. Here, we developed an electromagnetic localization technology for intraluminal tumor localization based on injectable magnetic hydrogel with sustained magnetization properties (MagLabel-IH). Following endoscopic injection into the gastrointestinal tract and in situ realignment, MagLabel-IH enables continuous intraluminal magnetic signal tracing. Intraoperatively, a dynamic registration framework synchronizes the magnetic coordinate system with real-time anatomical positions under visual guidance, achieving precise localization of optically invisible intraluminal tumors. The system demonstrated exceptional surgical instrument maneuverability (e.g., tissue grasping, resection path selection) during MagLabel-IH detection. In vivo animal evaluations demonstrated significantly enhanced localization accuracy compared to conventional biological dyes tattooing (3.8 ± 0.8 mm vs. 16.8 ± 8.6 mm, P < 0.05). Furthermore, the magnetic labels-based localization system exhibited promising utility for tumor margin demarcation and planning of gastrointestinal functional reconstruction.