Purpose: To determine 24- and 48-hour distribution of iodine-123 metaiodobenzylguanidine (MIBG) and to establish an optimized pediatric imaging protocol.
Materials and methods: Seventy-seven I-123 MIBG scans obtained in 33 children undergoing evaluation for neural crest tumor were reviewed.
Results: Activity in the salivary glands, myocardium, liver, gut, and bladder was demonstrated on almost all scans. Activity was noted in the neck muscles, thyroid gland, and uninvolved adrenal gland in fewer studies. In 20 studies, abnormal uptake was present in the chest or abdomen at 24 and 48 hours, and lesion identification was improved at 48 hours in 12 studies. Detection of skeletal lesions on 14 scans was similar at 24 and 48 hours. Foci of tumor were first detected at I-123 MIBG imaging in nine studies, and in only two patients was tumor involvement initially missed on I-123 MIBG studies.
Conclusion: Distribution of I-123 MIBG on images in children differs from that in earlier descriptions in adults. Images of the torso at 48 hours after injection are a useful adjunct in detection of lesions.