Imaging of catecholamine-secreting tumours: uses of MIBG in diagnosis and treatment.

MIBG radiolabelled with 131I or 123I is a radiopharmaceutical which is concentrated in neuroendocrine tumours, particularly phaeochromocytomas and neuroblastomas. This permits non-invasive whole-body scintigraphic screening for benign and malignant, familial and sporadic, intra-adrenal and extra-adrenal phaeochromocytomas and primary and metastatic neuroblastomas, with high sensitivity (85-90%) and specificity (> 95%). MIBG is also concentrated in presynaptic terminals of adrenergic, autonomically innervated organs such as the heart, and may be used as a non-invasive in vivo probe to study this system. Large doses of 131I-MIBG and 125I-MIBG have been used experimentally to selectively deliver therapeutic doses of radiotherapy to malignant phaeochromocytomas and refractory advanced neuroblastomas.