Development of Endoscopic CT Lymphography for Mapping Sentinel lymph node in esophageal cancer

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To evaluate the feasibility of endoscopic computed tomographic lymphographic (CTLG) technique with submucosal injection of a widely-available contrast agent iopamidol for direct visualization of drainage lymphatic pathways in dogs and in patients with operable esophageal cancer. With approval by the institution's animal committee, a total of 2 ml undiluted iopamidol was injected into esophageal (n = 6) or gastric (n = 3) submucosa in 9 anesthetized dogs, using a flexible endoscopy. The 1.25-mm thick multidetector-row CT images were obtained prior to contrast injection and during 10 min after injection. These animals were euthanized to examine lymphatic anatomy. With approval by ethical committee and informed consent from patients, 9 patients with operable esophageal cancer similarly underwent CTLG, but with peritumoral injection of 2 ml iopamidol, followed by esophagotectomy and regional lymph node dissection under CTLG guidance. Histopathology of dissected nodes including SLNs was examined. CTLG visualized the direct connection of the drainage lymphatic vessels and enhanced/unenhanced nodes [i.e., sentinel lymph nodes (SLNs)] as early as within 5 min after contrast injection in all subjects, with an interobserver consistency. All 13 SLNs in dogs (1.4 nodes per animal) and 18 SLNs in patients (2 nodes per patient) could be found and dissected at the correct location under CT-LG guidance. In patients, histopathological examination indicated successful probability of CTLG-guided SLN biopsy; metastasis was positive only in one of the preoperatively identified SLNs in 3 patients and in both SLNs and adjacent nodes in 2 patients, and negative in all resected nodes in the remaining 4 patients. Endoscopic CTLG is feasible for visualizing direct connection and accurate anatomic location of SLNs and drainage lymphatic vessels.