131I MIBG is taken up and stored by neural crest tumors, essentially pheochromocytoma and neuroblastoma. MIBG diagnosis in neuroblastoma has been attempted with the following results. 205 total body scintigrams were performed in 60 patients with neuroblastoma with doses of MIBG ranging from 0.5 to 1 mCi. 52 were positive, 6 in complete remission were negative, and 2 were false negatives in adults with tumors showing no secretion of metabolites. More than 90% of neuroblastoma are MIBG positive, and therefore MIBG imaging is now considered the most valuable means of diagnosis and staging of these tumors. 131I MIBG therapy has been attempted in 22 patients with neuroblastoma. They received multiple therapeutic doses of 41 to 2,090 mCi given IV at 3- to 6-week intervals. The results were 5 complete remissions, 10 partial remissions, 1 no change, 2 progressive disease and 1 lost to FU. Apart from bone marrow depression in patients with previous bone marrow involvement, the treatment was well tolerated. Six adults with other neural crest tumors were also treated. Pain relief in metastatic patients is a common and important result of MIBG therapy.
3-Iodobenzylguanidine Adolescent