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

This single-center, open-label diagnostic imaging study investigates the clinical utility of somatostatin receptor (SSTR) and norepinephrine transporter (NET) targeted molecular imaging for detection, staging, and treatment planning in patients with neuroblastoma and pheochromocytoma/paraganglioma (PPGL). The biological rationale rests on the frequent overexpression of NET in sympathoneuronal tumors and SSTR in neuroendocrine-derived neoplasms, enabling high-contrast visualization of primary and metastatic disease, including bone and bone marrow involvement. The protocol emphasizes harmonized acquisition and reconstruction parameters, quantitative analysis, and rigorous comparison against a composite reference standard comprising histopathology when available and multidisciplinary clinical adjudication.

The imaging strategy purposefully includes a broad spectrum of tracers within the SSTR and NET classes to capture complementary biology and to accommodate variability in patient phenotype, prior therapies, and local availability. For NET-targeted imaging, the study may employ 123I-metaiodobenzylguanidine (123I-MIBG) with planar and SPECT/CT techniques, 131I-MIBG as a legacy diagnostic alternative where appropriate, 18F-meta-fluorobenzylguanidine (18F-MFBG) for PET/CT or PET/MRI with improved resolution and logistics, 18F-LMI1195 as an investigational PET agent subject to site availability, 11C-hydroxyephedrine (11C-HED) PET where a cyclotron is accessible, and 18F-fluorodopamine (18F-FDA) PET in centers with established protocols. For SSTR-targeted imaging, the protocol allows 68Ga-DOTATATE, 68Ga-DOTATOC, and 68Ga-DOTANOC PET/CT or PET/MRI as contemporary standards; 64Cu-DOTATATE to leverage its longer half-life and extended imaging window; 18F-labeled SSTR agents such as 18F-SiTATE and 18F-AlF-NOTA-octreotide where available; and legacy SPECT agents including 111In-pentetreotide (Octreoscan) and 99mTc-HYNIC-TOC or 99mTc-EDDA/HYNIC-TOC depending on local practice. Tracer selection is individualized based on clinical indication, age, renal and hepatic function, concomitant medications, and logistical factors; when clinically justified and feasible, intra-patient multi-tracer imaging within and across SSTR and NET classes may be performed to enable head-to-head comparisons.

FDG and CXCR4 PET/CT or PET/MRI may be performed solely as optional comparator imaging at investigator discretion and contingent on site capability and local approvals. Optional comparators include 18F-FDG and CXCR4-targeted agents such as 68Ga-Pentixafor (and 64Cu-Pentixafor where permitted). These scans are not required for enrollment or primary analyses but may support exploratory comparisons in predefined subgroups.

Radiopharmaceutical preparation follows good manufacturing practice with predefined batch release specifications, including radiochemical purity (typically ≥95% for PET peptides), acceptable pH range, sterility, endotoxin limits, and specific activity as applicable. Each batch is accompanied by a certificate of analysis, lot traceability, and temperature and transport documentation, and any deviations are handled under corrective and preventive action procedures. Handling, storage, and administration comply with institutional radiation safety policies and national regulations. For optional comparator agents, applicable pharmacopeial or investigator's brochure specifications are followed.

Patient preparation adheres to tracer-specific guidance. For NET imaging, medications that interfere with catecholamine transport or storage (for example, labetalol and certain antidepressants) are reviewed and managed per site standard operating procedures, and thyroid blockade is implemented when indicated for radioiodine-labeled agents. For SSTR imaging, somatostatin analogues are managed to minimize receptor blockade when clinically appropriate. Hydration and frequent voiding are encouraged to reduce background activity. When optional 18F-FDG imaging is performed, patients fast for at least 4-6 hours, non-glucose-containing hydration is encouraged, strenuous exercise is avoided for 24 hours, and blood glucose is checked and documented prior to injection; insulin correction, if used, follows site policy to avoid altered biodistribution. When optional CXCR4 imaging is performed, no specific dietary restrictions apply; recent exposure to hematopoietic growth factors (for example, G-CSF) is recorded, and imaging may be deferred when clinically safe to mitigate confounding marrow uptake.