Colonoscopic indirect lymphangiography in a canine model.

Colorectal malignancies metastasize most frequently to mesenteric lymph nodes. Preoperative staging of these nodes by current modalities is problematic. This study evaluates the feasibility of indirect mesenteric lymphangiography as a colonoscopic technique in a canine model. Ten mongrel dogs underwent endoscopic submucosal injection of Ethiodol at various sites in the transverse, descending, and rectosigmoid areas. Serial abdominal roentgenograms were obtained up to 2 weeks postinjection. In seven of the animals, demonstration of mesenteric nodal uptake corresponding to the area(s) of injection was radiographically documented. In the remaining animals (early in the series) nodal opacification was inadequate. This lack of nodal uptake appeared to be due to nonsubmucosal contrast injection. No complications were noted. Colonoscopic indirect lymphangiography appears to be a safe and potentially useful modality in the evaluation of mesocolonic lymph nodes. Further studies to refine this technique and investigate its potential to preoperatively delineate abnormal nodal architecture are warranted.