Skeletal assessment in neuroblastoma--the pitfalls of iodine-123-MIBG scans

This study was carried out to compare iodine-123 metaiodobenzylguanidine ([I123I]MIBG) and technetium-99m-methylene diphosphonate bone scans (99mTc-MDP) in the detection of skeletal involvement by neuroblastoma. Forty-four children with neuroblastoma underwent both [123I] MIBG and 99mTc-MDP scans within a 4-wk period; bone marrow examination also was performed; all these investigations were done both at diagnosis and at follow-up. At diagnosis, four children with Stage 4 disease had normal [123I]MIBG scans but abnormal 99mTc-MDP scans, while at follow-up there were four children with negative [123I]MIBG studies who later died from disseminated neuroblastoma. All eight scans are considered false-negative. In 24 children, the [123I]MIBG revealed more extensive disease with 161 positive sites while the 99mTc-MDP scan showed only 100 positive sites; 34 of these sites were common to both studies. This study shows that underassessment of skeletal involvement by neuroblastoma occurred using [123I]MIBG scans and that one cannot therefore substitute [123I]MIBG for 99mTc-MDP bone scans in the staging of neuroblastoma.