Study of the Diagnostic Value of Hybrid PET/MR and PET/CT in Neuroendocrine Diseases and Tumor Induced Osteomalacia

Neuroendocrine tumors (NETs) are rare neoplasms arising from the diffuse endocrine system and spreading throughout the different organs and tissues of the body. Tumor-induced osteomalacia (TIO), is a rare, serious paraneoplastic syndrome primarily derived from a benign tumor of mesenchymal tissue. NETs and mesenchymal tumors are often insidious and are undetectable by conventional imaging techniques including ultrasound, computed tomography and magnetic resonance, while a permanent cure will rely on exact localization and completely removal of the tumor.

Positron emission tomography (PET) provides a valuable tool for the diagnosis and differential diagnosis, staging, efficacy evaluation and recurrence monitoring of various tumors. NETs and mesenchymal tumors overexpress somatostatin receptors (SSTRs), so molecular imaging using radiolabeled somatostatin analogues may be one of the best ways to detect the occult tumors. Recently, somatostatin analogue labelled with gallium-68 (68Ga-DOTA-TATE) as a novel positron tracer has shown to be effective for the detection of NETs and mesenchymal tumors. In this prospective study, the investigators will use the most advanced imaging equipment, integrated PET/MR，and PET / CT with specific imaging agent 68Ga-DOTA-TATE and conventional imaging agent [F-18] fluorodeoxyglucose to image patients. For patients suspected of or diagnosed with NETs and TIO, the investigators aim to evaluate the roles of integrated PET/MR and PET/CT in differential diagnosis, detecting primary and metastatic lesions, guilding biopsy, staging and determining treatment plan prior to treatment; for patients with a history of NETs and TIO, the aim is to evaluate the value of integrated PET/MR and PET/CT for treatment response assessment, detection of recurrences and metastatic lesions; for patients with inoperable and metastatic NETs, the aim is to find the value of integrated PET/MR and PET/CT in assessing the expression level of SSTRs to guide peptide receptor radionuclide therapy.