Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In-111 pentetreotide scintigraphy of 10 patients with residual or metastatic medullary thyroid carcinoma is described. Six patients had sporadic tumor and 4 had MEN IIB. Foci of increased tracer uptake were observed in 9 patients: in the thyroid bed (4 patients), the mediastinum (3 patients.), the shoulder area and left lower abdomen (1 patient), and the left upper abdomen (1 patient). The 10th patient had no abnormal uptake. CT confirmed 2 mediastinal lesions and 2 out of 3 thyroid masses, but did not detect the thyroid remnants or the lesions in the shoulder area and abdomen. Lung lesions < or = 1 cm in diameter and ill-defined liver foci (2 patients) were seen on CT, but not on scintigraphy. Small liver metastases not demonstrated on CT or on scintigraphy were identified at surgery in a MEN IIB patient. Elevated urinary epinephrine was found in 2 out of 4 MEN IIB patients. In one, tracer uptake in the left adrenal corresponded to a mass on CT, to pathological uptake of MIBG and DMSA, and to a tumor removed at surgery. The second patient had peritoneal spread of malignant pheochromocytoma (at surgery), but negative CT and only a single focus in the left lower abdomen on scintigraphy. Somatostatin-receptor imaging is useful for the detection of residual and recurrent medullary thyroid carcinoma, and may identify pheochromocytoma in MEN IIB patients.
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PMID:Somatostatin-receptor imaging of medullary thyroid carcinoma. 791 71

The aim of this study was to evaluate the effectiveness of a recently developed radiolabelled somatostatin analog (111In-pentetreotide) for the detection and localization of both medullary thyroid carcinoma (MTC) and carcinoid tumors, and to compare the results obtained with the results of 99mTc(V)-DMSA, and radioiodinated MIBG imaging. 111In-pentetreotide scintigraphy was performed in 9 patients with MTC and in 9 patients with carcinoid tumor. Whole body and SPECT studies were performed at 4 and 24 hours post-injection. SMS scintigraphy gave a positive result in 5 out of 7 patients with proven MTC lesions, and in 7 out of 9 patients with known lesions of carcinoid tumor. It gave a negative result in 2 MTC patients with high levels of calcitonin but with no evidence of disease at conventional diagnostic modalities. The scintigraphic results were comparable with those obtained with 99mTc(V)-DMSA in MTC and were superior to those of radioiodinated MIBG in both MTC and carcinoid tumors. When compared with the modifications of calcitonin levels brought about by the acute administration of octreotide ("Octeotride test"), these correlated well in 8 out of 9 patients studied.
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PMID:Radiolabeled somatostatin analog scintigraphy in medullary thyroid carcinoma and carcinoid tumor. 900 74

Early diagnosis of metastases of medullary thyroid carcinoma (MTC) provides the optimal condition for curative outcome. The aim of this study was to appraise the detection of metastases in patients with recurrent MTC using [111In-DTPA-d-Phe1]-pentetreotide and pentavalent technetium-99m dimercaptosuccinic acid [99mTc(V)-DMSA] in comparison with histopathological findings. Eighteen MTC patients with persistently elevated tumour marker (calcitonin, carcinoembryonic antigen) levels underwent somatostatin receptor scintigraphy using [111In-DTPA-d-Phe1]-pentetreotide (222 MBq) with early (4 h after injection) and delayed (24 h) whole-body scans and single-photon emission tomography (SPET) imaging. Metabolic whole-body and SPET imaging using 500 MBq 99mTc(V)-DMSA was performed 4 h after injection. Metabolic and receptor imaging revealed 51 sites of focal accumulation in the 18 patients investigated. Comparison with histological findings revealed that metabolic and receptor imaging had a sensitivity of 84% for the diagnosis of MTC. Using [111In-DTPA-d-Phe1]-pentetreotide, SPET discovered four lymph node metastases in two patients in whom planar views had previously identified only one lymph node metastasis, and provided no new information in the other 16 patients. In comparison, SPET studies [using 99mTc(V)-DMSA] additionally localized eight lymph node metastases in four patients and confirmed the diagnosis of hepatic metastases (n=5) in another patient in whom conventional imaging modalities and planar views had previously detected only three liver metastases. Overall, lesion detection sensitivities for 99mTc(V)-DMSA and [111In-DTPA-D-Phe1]-pentetreotide were 69% and 29%, respectively. Five surgically removed foci were adjudged false-positive with respect to MTC metastases. False-positve results were caused by lymphadenitis, an enchondroma and a pheochromocytoma (histologically proven). The smallest lesion identified by metabolic imaging was a 6 mm in diameter lymph node metastasis located in the upper mediastinum. Somatostatin receptor scintigraphy only demonstrated tumour sizes more than 1 cm in diameter. These preliminary results suggest that the combination of metabolic [99mTc(V)-DMSA] and receptor ([111In-DTPA-D-Phe1]-pentetreotide) imaging is more sensitive for tumour localization in patients with recurrent MTC than the use of only one radiopharmaceutical. However, neither 99mTc(V)-DMSA nor [111In-DTPA-D-Phe1]-pentetreotide is specific for MTC and false-positive scintigraphic findings have to be considered. Furthermore, somatostatin receptor scintigraphy cannot visualize small tumour sites (<1 cm). Further studies are needed to evaluate the role of combined metabolic and receptor imaging in the management of patients with recurrent MTC.
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PMID:Comparison of metabolic and receptor imaging in recurrent medullary thyroid carcinoma with histopathological findings. 1004 54

With the variety of radiopharmaceutical agents and refined imaging techniques, thyroid and parathyroid imaging provides much valuable clinical information. The use of imaging is most important in the follow-up of differentiated (DTC) and medullary thyroid cancer (MTC). Patients with DTC are followed with serum thyroidglobulin and 131I whole body scintigraphy when the serum thyroglobulin level is elevated. When the 131I scintigram is negative, 201Tl scintigraphy may best identify the site of recurrent DTC. Alternative radioisotopes, ultrasound, CT, and FDG PET are also useful in localizing the site of DTC metastases. MTC recurrences and metastases are more difficult to image. Selective venous catheterization is the most sensitive and specific method for detecting areas of recurrent MTC. High-resolution ultrasound, CT, MR imaging, and scintigraphy are all capable of, and useful in, detecting macroscopic foci of metastatic tumor. Somatostatin receptor scintigraphy and 99mTc DMSA have been the most frequently used nuclear imaging agents in patients with recurrent MTC. Imaging for hyperparathyroidism remains controversial. Sestambi has become the preferred isotope for parathyroid scintigraphy; whereas high-resolution ultrasound is also frequently used. Preoperative imaging is being used as a method to allow a unilateral neck exploration, more recently, in conjunction with intraoperative 1-84 PTH assay and with intraoperative use of the gamma probe. Most often, parathyroid imaging is performed before reoperation for persistent hyperparathyroidism.
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PMID:The use of imaging studies in the diagnosis and management of thyroid cancer and hyperparathyroidism. 982 66

Neuroendocrine tumors are characterized by the expression of different peptides and biogenic amines. These rare tumors tend to grow slowly and are notoriously difficult to localize, at least in the early stages. Surgical removal is the only definitive therapeutic option for neuroendocrine tumors and relief from hyperfunctional status. The effectiveness of surgical treatment is invariably dependent upon the complete surgical excision of all tumor tissue, because microscopic and occult disease not readily seen by the surgeon may remain in situ, leading to shortened survival. Therefore, pre- and intraoperative localization of the primary as well as of metastatic tumors is of utmost importance. Radioguided surgery (RGS) is an intraoperative technique that enables the surgeon to localize radiolabelled tissue based on the characteristics of the various tissues. Concerning gastroenteropancreatic tumors (GEP), intraoperative gamma probe examination is able to reveal small tumor sites accumulating (111In-DTPA-D-Phe1)-pentetreotide more efficiently (> 90%) than somatostatin receptor scintigraphy (68%-77%), because lesions with a size smaller than 5 mm in greatest dimension could be identified. Furthermore, RGS identified 57% more lesions when compared to the "palpating finger" of the surgeon. In medullary thyroid cancer (MTC), surgical removal of the tumor is the first and most efficient treatment of the disease. Persistent or increasing serum calcitonin and carcinoembryonic antigen (CEA) levels imply tumor recurrence after thyroid ablation. For imaging recurrent MTC many radiopharmaceuticals have been used to visualize tumor sites, but none of them has shown excellent sensitivity. Preoperative somatostatin receptor scintigraphy and intraoperative RGS in patients with recurrent MTC demonstrate only part of the tumor sites and cannot visualize small tumor sites (less than 10 mm). In comparison, RGS using 99mTc(V)-DMSA detects metastases with a size of 5 mm in diameter, whereas the "palpating finger" of the surgeon localized metastases with a size of more than 1 cm in diameter. In patients with recurrent MTC, intraoperative gamma probe examination is able to localize over 30% more tumor lesions when compared with conventional preoperative imaging modalities and surgical findings. MIBG scintigraphy is the most sensitive technique for the detection and staging of neuroblastoma (sensitivity 92%; specificity nearly 100%). Intraoperative RGS with iodine labelled MIBG has been developed to improve the definition of tumor limits or to localize small, nonpalpable tumors. Comparison of 123I- and 125I-labelled MIBG revealed a sensitivity of 91% and 92%, respectively; the specificity of 125I (85%) was significantly higher than that of 123I (55%). In addition to scintigraphy of the adrenal glands by precusors of adrenal hormones, imaging with a radiolabelled somatostatin analogue is possible; however, (111In-DTPA-D-Phe1)-pentetreotide is not specific for any adrenal disease or function and the relatively high radioligand accumulation in the kidneys limited the use for detection of tumors in the area of the adrenal glands.
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PMID:Intraoperative use of gamma-detecting probes to localize neuroendocrine tumors. 1093 2

Medullary thyroid carcinoma (MTC) originates in the parafollicular cells (C cells) of the thyroid, secreting both calcitonin and CEA. Genetic and biochemical testing allow early pre-clinical identification of familial forms. Sporadic MTC usually presents as a solitary palpable thyroid nodule and in most cases the definitive diagnosis is established only at the time of surgery. Nuclear medicine procedures, which play a minor role in the preoperative evaluation of MTC, are essential in postoperative follow-up to detect residual and/or recurrent tumor. A number of radiopharmaceuticals are able to visualize MTC lesions with considerable advantages in diagnosis and prognosis, some of them having also a therapeutic role. Among them, 99mTc[V]DMSA shows the highest diagnostic sensitivity and is considered by many authors the radiopharmaceutical of choice in the postoperative work-up of MTC. Radioiodinated MIBG, in spite of its high specificity has a poor sensitivity (30%); however it is useful for the identification of pheochromocytoma and, in patients showing MIBG uptake in tumoral lesions, high activities of 131I-MIBG may be used for therapy. 111In labeled octreotide detects lesions which express somatostatin receptors; a positive scintigraphic result seems to give also prognostic information (higher uptake in slow-growing lesions) and provides the basis for treatment with octreotide or lanreotide and 111In or 90Y-labeled octreotide analogues. Interesting perspectives are offered by 18F-FDG PET and monoclonal anti-CEA labeled antibodies; the latter may be also used for therapy.
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PMID:Role of nuclear medicine in the diagnosis and therapy of medullary thyroid carcinoma. 1137 May 45

Current therapeutic approaches in neuroendocrine tumours include surgery, radiotherapy and polychemotherapy. Different metabolic patterns of neuroendocrine tumours allow the use of a wide range of diagnostic options in nuclear medicine, due to the presence of a wide spectrum of radiotracers electively concentrating in these neoplasms. Nuclear medicine, and in particular 111In Octreotide (OCT) scintigraphy, 123I Methaiodobenzylguanidine (MIBG) and pentavalent 99mTc-DMSA (V-DMSA), together with biohumoral markers, are currently able to locate tumours also not detectable using traditional diagnostic techniques. Somatostatin analogs, such as octreotide have become increasingly important over the years in the treatment of patients with neuroendocrine tumours. At present the therapeutic use of somatostatin analogs can be schematised as 1) pharmacological treatment (with cold octreotide); 2) surgical treatment (radioguided surgery); 3) radiometabolic treatment (with marked octreotide). The development of new synthetic molecules and new radiocompounds will probably open up interesting scenarios in the near future.
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PMID:[Role of somatostatin analogs in the treatment of neuroendocrine tumours]. 1175 36

Neuroendocrine tumours can be visualized by several nuclear medicine modalities based on different mechanisms of cellular uptake. The most widely used radiopharmaceutical are the metaiodobenzylguanidine (123I/131I MIBG) and pentetreotide (111In pentetreotide). The first tracer follows the metabolic pathway of norephinephrine while the second one binds to somatostatin receptors which are expressed with high intensity on the neuroendocrine tissue. Some radiopharmaceuticals (Anti-CEA, Anti-CgA, Anti-GD2 monoclonal antibodies) have today only an experimental value, others such as 99mTc(V)DMSA had in the past very limited indications (medullary thyroid cancer) but at present their production is going to be stopped. An interesting series of new peptides showing a great affinity for the receptors/structures expressed by the neuroendocrine tissue is under evaluation in order to obtain a better tumour specificity. Among the positron-emitting radiopharmaceuticals, the 18F-fluorodeoxyglucose (FDG), in spite it is considered the most widely used tracer for clinical PET in oncology, did not show a satisfactory uptake in the well differentiated neuroendocrine tissues. On the contrary 18F-FDG is the best radiopharmaceutical to visualize those rare poorly differentiated neurondocrine tumours with a high proliferative index. For this reason also in this area, new radiopharmaceuticals have been studies and developed. A serotonin precursor 5-hydroxytryptophan (5-HTP) labelled with 11C has shown an increased uptake in carcinoids. Another radiopharmaceutical in development for PET is 11C L-DOPA which seems to be useful in visualizing endocrine pancreatic tumours. 18F-DOPA whole body PET may be a more promising imaging approach. Aim of this review is to summarize the potential of nuclear medicine techniques in the diagnosis of neuroendocrine tumours and to stresses the renewed role of nuclear medicine in the management of this disease.
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PMID:[Radioisotopic imaging of neuroendocrine tumours. Which radiopharmaceutical and which diagnostic procedure?]. 1178 5

Neuroendocrine tumors (NETs) represent a large group of neoplasms deriving from pluripotent stem cells or from differentiated neuroendocrine cells that are characterized by the expression of different peptides and biogenic amines. These rare tumors tend to grow slowly and are notoriously difficult to localize, at least in the early stages. Diagnostics involve blood, urine and biochemical examination as well as imaging modalities. Imaging is achieved by a variety of techniques such as radiological morphological imaging methods, for example, sonography, computerized tomography (CT)/magnetic resonance imaging (MRI), angiography and finally, nuclear functional imaging methods such as metaiodobenzylguanidine (MIBG), somatostatin receptor scintigraphy (SRS), vasoactive intestinal peptide receptor scintigraphy (VIPRS) and positron emission tomography (PET) using (18)F labeled deoxyglucose (FDG) and fluorinated dihydroxyphenylalanine ((18)F-DOPA) as a radioisotopic marker. (131)I-labeled MIBG is a well-established radiopharmaceutical for localization and therapy of phechromocytoma and paraganglioma. The majority of neuroendocrine tumors possess a high density of somatostatin receptors. This observation provided the basis for the development of various radiolabeled somatostatin peptide analogs as imaging agents and therapeutics in nuclear medicine. FDG-PET is now performed in a wide variety of tumors and indications, including diagnosis, staging, re-staging and evaluation of the response to treatment. (18)F-DOPA-PET may be useful if (18)F-FDG-PET scan result is negative. (99m)Tc-pentavalent dimercaptosuccinic acid ((99m)Tc-DMSA-V) or (99m)Tc sestamibi ((99m)Tc-MIBI) or (99m)Tc-tetrofosmin is used only for diagnosis of certain NETs such as medullary thyroid cancer. The expiences with other nuclear medicinie imaging and therapy modalities such as cholecystokinin (CCK)-B/gastrin-receptors, bombesin/gastrin-releasing peptide receptor scintigraphy are still limited, and further clinical studies are needed. The studies using vascular endothelial growth factor (VEGF) for tumor angiogenesis imaging, annexin-V for imaging apoptosis and agents for hypoxia imaging are still in an early stage and the clinical role for these agents needs to be defined. In conclusion, no single imaging technique identifies all the metastatic sites of NETs. The best results may be obtained with a combination of functional imaging such as PET or/and SRS and morphologic imaging with CT and/or MR imaging. Many molecular imaging and therapy modalities fur NETs are recently under investigation or being developed, the usefulness of these modalities, however, has to be evaluated by well-designed and multicentre studies.
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PMID:The radionuclide molecular imaging and therapy of neuroendocrine tumors. 1581 Aug 78

Neuroendocrine tumors can originate almost everywhere in the body and consist of a great variety of subtypes. This paper focuses on molecular imaging methods using nuclear medicine techniques in neuroendocrine tumors, coupling molecular uptake mechanisms of radiotracers with clinical results. A non-systematic review is presented on receptor based and metabolic imaging methods. Receptor-based imaging covers the molecular backgrounds of somatostatin, vaso-intestinal peptide (VIP), bombesin and cholecystokinin (CCK) receptors and their link with nuclear imaging. Imaging methods based on specific metabolic properties include meta-iodo-benzylguanide (MIBG) and dimercapto-sulphuric acid (DMSA-V) scintigraphy as well as more modern positron emission tomography (PET)-based methods using radio-labeled analogues of amino acids, glucose, dihydroxyphenylalanine (DOPA), dopamine and tryptophan. Diagnostic sensitivities are presented for each imaging method and for each neuroendocrine tumor subtype. Finally, a Forest plot analysis of diagnostic performance is presented for each tumor type in order to provide a comprehensive overview for clinical use.
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PMID:Molecular imaging in neuroendocrine tumors: molecular uptake mechanisms and clinical results. 1936 10


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