title: Gastrointestinal iodine-131-meta-iodobenzylguanidine activity.
abstract: Radioactivity in the colon during 131-I-meta-iodobenzylguanidine (MIBG) scintigraphy may obscure or be mistaken for tumor uptake. Fecal excretion of radioactivity was examined in eight patients following therapeutic 131-I-MIBG administration (123-218 mCi, 4.551-8.066 GBq) and was found to be 0.02-1.93% of the administered dose. Semiquantitative grading of colonic activity on scintigraphy was inversely related to fecal excretion. An additional patient with marked colonic activity was studied before and after an enema: all visible gut activity was evacuated. We conclude that radioactivity in the colon seen in 131-I-MIBG scintigraphy is due largely to gut excretion of 131-I and is not due to 131-I-MIBG uptake in the autonomic innervation of the gut. Laxatives and enemas are suggested for patients in which such gut radioactivity may lead to difficulties in interpretation.
authors.affiliation: Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109.
authors.forename: O
authors.initials: O
authors.lastname: Geatti
authors.forename: B
authors.initials: B
authors.lastname: Shapiro
authors.forename: B
authors.initials: B
authors.lastname: Shulkin
authors.forename: R
authors.initials: R
authors.lastname: Hutchinson
authors.forename: J C
authors.initials: JC
authors.lastname: Sisson
mesh_terms: D019797:3-Iodobenzylguanidine; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging*; D000328:Adult; D003106:Colon / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D008297:Male; D008875:Middle Aged; D009447:Neuroblastoma / Q000000981:diagnostic imaging*; D010673:Pheochromocytoma / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D014018:Tissue Distribution
chemical_list: D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D019797:3-Iodobenzylguanidine