Best imaging modality for neuroendocrinal tumors?

C i.e. Radionucleotide Scan Neuroendocrinal tumors (NET) are derived from diffuse neuroendocrine system of gastrointestinal (GI) tract, which is composed of amine & acid producing cells with different hormonal profiles, depending on the site of origin. NET refers to two type of tumors Name Biologically active peptide secreted I. Carcinoid Tumor II. Pancreatic Endocrinal Tumor (PET) SerotoninQ, possibly tachykinin, motilin, Prostaglandin - Zollinger-Ellison Syndrome GastrinQ - Insulinoma Insulin - Glucagonoma Glucagon - Somatostatinoma Somatostatin - GRF-oma Growth Harinone Releasing HannoneQ - ACTH-oma ACTH - VIP oma (Verner Morrison Vasoactive intestinal peptide (VIP) Syndrome/WDHA, Pancreatic cholera) - PET causing Carcinoid syndrome Serotonin, ? tachykinin - PET causing hypercalcemia PTHrP Because of its greater sensitivity than conventional imaging (CT, MRI, USG) and its ability to localize tumor throughout the body at one time. SRS (Somatostatin receptor Scintigraphy) is now the imaging modality of choice for localizing both primary and metastatic NET tumorsQ. (except for Insulinoma)Q. Best modality of localizing Insulinoma is endoscopic WS. Somatostatin receptors are of 5 types, radiolabeled octreotide binds with highest affinity to SS2 receptor. SRS is not a diagnostic investigation. Diagnosis is confirmed by detecting peptides or amines (or their metabolites) secreted by the tumors in urine or serum.