Development of Magnetic Probe for Sentinel Lymph Node Detection in Laparoscopic Navigation for Gastric Cancer Patients.

New laparoscopic sentinel lymph node navigation using a dedicated magnetic probe and magnetic nanoparticle tracer for gastric cancer patients allows minimally invasive surgeries. By identifying the sentinel lymph nodes containing magnetic nanoparticles, patients can avoid excessive lymph node extraction without nuclear facilities and radiation exposure. This paper describes the development of the laparoscopic magnetic probe, ACDC-probe, for laparoscopic sentinel lymph node identification utilizing the nonlinear response of the magnetic nanoparticles magnetized by an alternating magnetic field with a static magnetic field. For highly sensitive detection, the ratio of static to alternating magnetic fields was optimized to approximately 5. The longitudinal detection length was approximately 10 mm for 140 μg of iron, and the detectable amount of iron was approximately 280 ng at a distance of 1 mm. To demonstrate the feasibility of laparoscopic detection using the ACDC-probe and magnetic tracers, an experiment was performed on a wild swine. The gastric sentinel lymph node was clearly identified during laparoscopic navigation. These results suggest that the newly developed ACDC-probe is useful for laparoscopic sentinel lymph node detection and this magnetic technique appears to be a promising method for future sentinel lymph node navigation of gastric cancer patients.