[A new medico-nuclear outlook for the diagnosis and treatment of pheochromocytomas: 131I-meta-iodobenzylguanidine (131I-MIBG). Comments on results obtained]

Abstract

The diagnostic and therapeutic potential of 131I-MIBG, the new imaging agent with structural similarity to norepinephrine, was evaluated in 23 patients with a suspect pheochromocytoma. Seven out of 8 benign pheochromocytomas (2 ectopic) were correctly localized with 131I-MIBG scintigraphy (1 false negative). In 2 catecholamine-secreting malignant pheochromocytomas both the primary tumor and the metastases (1 case) were demonstrated. One uncommon case of dopamine-secreting malignant pheochromocytoma, as expected, was not shown. In the remaining 12 cases, found to be "normal" after completing the work-up, distribution of the radiopharmaceutical was evaluated using a semiquantitative grading system. 131I-MIBG scintigraphy proved to be a non invasive and accurate (95%) diagnostic modality, specific for neuroadrenergic tumors. The treatment with 131I-MIBG was also carried out in 2 malignant pheochromocytomas with encouraging results.