Imaging with I-131 MIBG has proved useful for the detection of pheochr
omocytoma, neuroblastoma, and other neoplasms of neural crest origin.
The authors present a case of a patient who was initially diagnosed as
having follicular carcinoma of the thyroid in which I-131 MIBG played
a key role in leading to the diagnosis of medullary carcinoma of the
thyroid. Local and distant metastases were detected using I-131 MIBG i
maging. Uptake of I-131 MIBG by medullary carcinoma of the thyroid has
both diagnostic and therapeutic implications.