Radioiodinated metaiodobenzylguanidine in neuroblastoma: influence of high dose on tumour site detection.

For more than a decade radioiodinated metaiodobenzylguanidine (mIBG) has been commonly used for neuroblastoma imaging. The accuracy of this scintigraphic method in detecting both primary and secondary tumour sites is crucial when evaluating the extent of disease. The aim of our study was to assess the impact of high-activity mIBG scintigraphy on neuroblastoma staging. Eighteen scans (TS) were obtained in 15 children after a therapeutic dose of iodine-131 mIBG and compared to diagnostic mIBG scans (DS) (in eight cases with 131I-mIBG and in ten cases with 123I-mIBG). The superiority of TS over DS was confirmed by the overall results: a total of 220 lesions were disclosed with TS and 171 with DS. However, in only one case did the TS findings, namely skeletal involvement not evidenced on corresponding DS, have an impact on clinical staging. In contrast, neither TS nor DS detected proven bone involvement in four patients. The dose-related sensitivity of mIBG scintigraphy in detecting neuroblastoma tumour sites was confirmed. The ultimate impact of high-dose scans on neuroblastoma management, however, seems limited.