Normal cerebellar MIBG localization. Implications in the interpretation of delayed scans.

In the I-131 MIBG scans of 14 patients with neuroblastoma (86%) or pheochromocytoma/paraganglioma (14%) that were studied more than 48 hours after administration of the radiopharmaceutical, 12 (86%) had discernible cerebellar MIBG localization. A few had midbrain or diffuse cerebral uptake as well. None of the patients had cerebellar or other central nervous system signs or symptoms, and the localization is consistent with the known distribution density of central nervous system catecholamine receptors. This suggests that cerebellar MIBG localization is normal in delayed scans and that it should not be confused with neuraxial metastasis of adrenergic neuronal neoplasms.