Comparison of [123I]MIBG and [131I]MIBG for imaging of neuroblastoma and other neural crest tumors.

Meta-iodobenzylguanidine (MIBG), an analog of the adrenergic neurotransmitter norepinephrine, has proven a valuable imaging agent for neuroendocrine and neural crest tumors. Over the past 3 decades, MIBG labeled with [131I] or [123I] has been used widely in imaging of neuroblastoma and pheochromocytoma. Before September 2008 [131I]MIBG was approved as a diagnostic agent only in the US. Due to the excellent physical characteristics of [123I] for imaging with modern scintillation cameras, [123I]MIBG is theoretically more suitable than [131I]MIBG in detecting tumors. In practice, use of [123I]MIBG or [131I]MIBG for diagnostic studies depends on availability and local preference. This review compares [123I]MIBG with [131I]MIBG in imaging of neuroblastoma and other neural crest tumors and also the physical properties of relevant radioisotopes. Dosimetry and scanning protocols of [123I]MIBG and [131I]MIBG, along with their value in depicting disease extent, assessing treatment response and predicting survival are also compared. The performance of post-therapy high-activity [131I]MIBG scans in lesion detectability is also addressed.