Intraoperative localization of colorectal tumors in the early stages using a magnetic marking clip detector system (MMCDS)

Background: In the laparoscopic surgical treatment of early stage colorectal carcinomas, intraoperative tumor site identification is often difficult. We developed a novel marking method using a magnetic marking clip and a modified magnetometer system. Methods: We applied magnetic marking clips at the tumor site during preoperative colonoscopy and identified the clip site with a magnetic marking clip detector system (MMCDS) of our design. Eleven patients who underwent laparoscopic colectomy were studied. Results: In a basic ex vivo study, magnetic bodies of more than 300 mT magnetic force were easily detected with a 100% detection ratio. In a clinical study, the marking site was detected in all 11 patients. The mean length between the detected site and clip along the longitudinal bowel axis was 14.1 mm (SD 5.6). The mean detection time was 2.4 min (SD 0.2). Conclusion: MMCDS accurately identifies tumor sites. This method may be useful for tumor site identification during laparoscopic colectomy.