Can MIBG scan replace the need for bone marrow assessment at diagnosis and reassessment in stage 4 neuroblastomas?

Complete staging (extensive marrow investigation and meta-iodo benzylguanine (MIBG) scan) is considered as mandatory both at diagnosis and after chemotherapy for assessment of metastases in neuroblastomas. However the correlation between bone marrow invasion and uptake of MIBG at metastatic sites remains unclear. This study investigates whether MIBG alone is sufficiently sensitive to make these procedures redundant.

20 children over one year of age, with histologically proven metastatic neuroblastoma were studied. Extensive bone marrow assessment and MIBG bone scan performed both at diagnosis and after completion of induction chemotherapy were reviewed.

At diagnosis metastases were detected by marrow investigation alone in 2, MIBG alone in 2 and both procedures in 16. After induction chemotherapy metastases were detected by only marrow investigation in 2, by only MIBG in 3, by both procedures in 6 patients, and by none in 9.

Whether marrow investigations and MIBG scan explore the same phenomenon remains unclear. However it appears that marrow disease that is histologically detectable may remain MIBG negative both at diagnosis and after treatment. Both procedures are still justified at time of diagnosis and evaluation of response.