Clinical Application of Somatostatin Receptor and Norepinephrine Transporter Targeted Imaging for Diagnosis and Staging of Neuroblastoma and Pheochromocytoma/Paraganglioma

Inclusion Criteria: * Age: ≥6 months (pediatric and adult). * Suspected or confirmed diagnosis of neuroblastoma (NB) or pheochromocytoma/paraganglioma (PPGL). * Clinical indication for SSTR and/or NET-targeted molecular imaging for initial staging, restaging, suspected recurrence, response assessment, or treatment planning. * Ability to undergo PET/CT or PET/MRI and/or SPECT/CT per protocol; for the PET/MRI subset, no MRI contraindications. * Provision of written informed consent/assent per local regulations. * Women of childbearing potential: negative pregnancy test within 72 hours prior to tracer administration and agreement to use effective contraception during the imaging window. * For the multi-tracer subset (if applicable): willingness to undergo two imaging studies within a predefined window (e.g., ≤28 days) without intervening antitumor therapy. Exclusion Criteria: * Pregnant or breastfeeding; breastfeeding participants unwilling to follow tracer-specific lactation interruption guidance per institutional policy. * Any condition that, in the investigator's judgment, precludes safe imaging or protocol compliance (e.g., uncontrolled cardiorespiratory disease, severe claustrophobia not amenable to sedation/anxiolysis). * Known hypersensitivity to study radiopharmaceuticals or their excipients. * Use of interfering medications without feasible washout: NET imaging: drugs that affect catecholamine transport/storage (e.g., labetalol, tricyclic antidepressants, certain sympathomimetics) per site SOPs. SSTR imaging: long-acting somatostatin analogues within \~3-4 weeks or short-acting within \~24-48 hours, unless clinically unavoidable. * Prior therapeutic or high-dose 131I-MIBG within a period that would confound diagnostic imaging or dosimetry (e.g., within 6 months), at the investigator's discretion. * Contraindications to required modality-specific procedures (e.g., MRI-incompatible implants for PET/MRI; iodinated/gadolinium contrast contraindication only if contrast is mandated and no alternative pathway is acceptable). * Inability to lie still for the required acquisition time and sedation not feasible per institutional policy. * Concurrent participation in an interventional study or receipt of anticancer therapy that would confound imaging interpretation within the imaging window; for multi-tracer comparisons, any interval systemic therapy between scans.