3. Any anti-cancer treatment planned between the routine [123I]mIBG imaging and the [124I]mIBG PET/CT scan on Day 2. Anti-cancer treatments can be started only after the Off-Study assessment on Day 3 to Day 7, see schedule of assessments in Section 7. N.B. Patients should not be enrolled in the study if their participation will delay their subsequent treatment for neuroblastoma.