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 suspected or confirmed NETs and TIO, the aim is to explore the value of hybrid PET/MR and PET/CT in neuroendocrine diseases and TIO.

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.

Inclusion Criteria:

• Patients with suspected or confirmed NETs or patients with suspected TIO

Exclusion Criteria:

• Acute systemic diseases and electrolyte disorders.
• Pregnant or lactating women.
• Participated in other clinical trials within 4 weeks before the start of the study.

About 90% of NETs, such as pancreatic endocrine tumors, pheochromocytoma, paraganglioma, gastrointestinal carcinoid, bronchial carcinoid, medullary thyroid carcinoma, small cell lung cancer, pituitary adenoma, some non-NETs (meninga) Tumor, astrocytoma, breast cancer, etc. have high expression of somatostatin receptor (SSTR).

TIO tumors are often derived from benign tumors of mesenchymal tissue, mostly located in bone or soft tissue, hiding in location, slow growth, and difficult to be found, making diagnosis difficult. According to reports in the literature, most of these tumors are positive for SSTR expression, and somatostatin receptor PET/CT imaging can locate lesions, which is a good method for screening TIO and has high specificity.