Qualitative and quantitative kinetics of submucosally administered antibody fragments in patients with rectal carcinoma: the detection of lymph node metastasis in relation to local tracer diffusion.

Immunoscintigraphy after submucosal administration of a mixture of 131I-anti-CEA and 131I-anti-CA-19-9 around the tumor in patients with rectal carcinoma may improve pre-operative staging and may contribute to the selection of patients eligible for local treatment. However, visual discrimination of local lymph node metastasis appears unreliable, partly because of scatter from the injection site and substantial diffusion of the radiotracer into the interstitium. Analysis of the diffusion profile, however, may improve the sensitivity and accuracy of this immunoscintigraphic approach.