Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1835664 (TOC)
 2,763 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several studies have reported on the expression of somatostatin receptors in patients with differentiated thyroid cancer (DTC). The aim of this study was to evaluate the imaging abilities of a recently developed technetium-99m labelled somatostatin analogue, (99m)Tc-EDDA/HYNIC-TOC ((99m)Tc-TOC), in terms of precise localisation of disease. The study population comprised 54 patients (24 men, 30 women; age range 22-90 years) with histologically confirmed DTC who presented with recurrent or persistent disease as indicated by elevated Tg levels after initial treatment. All patients were negative on the iodine-131 post-therapy whole-body scans. Fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) was performed in a subgroup of 36 patients. The study population consisted of two groups: Group A ( n=22) comprised patients with disease recurrence as shown by elevated Tg levels but without detectable pathology. In group B ( n=32), pre-existing lesions were known. Among the 54 cases, SSTR scintigraphy was true positive in 33 (61.1%), true negative in 4 (7.4%) and false negative in 17 (31.5%) cases, which resulted in a sensitivity of 66%. A total of 138 tumour foci were localised in 33 patients. The fraction of true positive (99m)Tc-TOC findings was positively correlated ( P<0.01) with elevated Tg levels (higher than 30 ng/ml). Despite two false positive findings, analysis on a lesion basis demonstrated better diagnostic efficacy with (18)F-FDG PET ( P<0.001); however, it also revealed substantial agreement between the imaging techniques [Cohen's kappa of 0.62 (0.47-0.78)]. In conclusion, scintigraphy with (99m)Tc-TOC might be a promising tool for treatment planning; it is easy to perform and showed sufficient accuracy for localisation diagnostics in thyroid cancer patients with recurrent or metastatic disease.
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PMID:99mTc-EDDA/HYNIC-TOC and (18)F-FDG in thyroid cancer patients with negative (131)I whole-body scans. 1462 64

An early diagnosis of distant metastases or local recurrences of medullary thyroid carcinoma (MTC) can be achieved by several conventional radiological modalities (e.g., ultrasonography, computed tomography [CT], and magnetic resonance imaging [MRI] as well as by radioisotopic procedures, such as positron emission tomography (PET), scintigraphy with different types of radiopharmaceuticals, and radiolabeled receptor-ligands in particular. The aim of this study was to evaluate the clinical utility of 99mTc-EDDA/HYNIC-TOC, a new octreotide derivative, to detect recurrences of disease or distant metastases in MTC. Images obtained of 5 patients with high levels of serum calcitonin were compared to findings obtained with other diagnostic procedures: 111In-octreotide, 99mTc-DMSA-V, 18F-flouro-D-deoxyglucose-PET, and CT/MRI. 99mTc-EDDA/HYNIC-TOC was positive in all patients and showed 15 areas of pathological uptake in the cervical and mediastinal regions. 111In-octreotide was positive in 3 of 3 patients and showed 4 areas, compared to 8 of 99mTc-EDDA/HYNIC-TOC. 99mTc-V-DMSA was positive in 3 of 4 patients but showed 6 pathological areas, compared to 13 of 99mTc-EDDA/HYNIC-TOC. 18F-FDG-PET was positive in 5 of 5 patients but showed only 11 areas, compared to 15 of 99mTc-EDDA/HYNIC-TOC. The CT scan was positive in only 2 patients. In conclusion, 99mTc-EDDA/HYNIC-TOC detected more sites of pathological uptake than other modalities, showed better imaging properties than 111In-octreotide, and might be the radiopharmaceutical of choice for providing a rationale for radioisotopic therapy.
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PMID:99mTc-EDDA/HYNIC-TOC in the management of medullary thyroid carcinoma. 1518 2

Radiolabeled tracers provide a functional imaging technique to identify neuroendocrine tumors, usually with greater sensitivity and specificity than anatomic imaging techniques such as computed tomography (CT), magnetic resonance imaging and ultrasound. Currently, there are several single-photon techniques available using either (123)I-MIBG, (111)In-DTPA-pentetreotide (Octreoscan) or (99m)Tc-EDDA/HYNIC-tyr3-octreotate. (111)In-DTPA-pentetreotide is most widely used. The best results are achieved with single-photon emission computed tomography/CT. Positron emission tomography (PET) and PET/CT are likely to provide further improvements in tumor detection, but there is, at the present time, no consensus on the choice of tracer. (18)F-FDG, (68)Ga-DOTA-TOC and (68)Ga-DOTA-NOC, (18)F-FP-Gluc-TOCA, (18)F-FDOPA and (11)C-5HTP (hydroxy tryptophan) are currently being evaluated. Early results and issues pertaining to availability are reviewed. The identification of the 'best' tracer will depend on multiple factors.
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PMID:Update on nuclear medicine imaging of neuroendocrine tumors. 1924

Nuclear medicine can image some tumors by means of receptor specific radiopharmaceuticals, and offers the possibility to characterize cancer through the detection of its receptor expression. This is the case of neuroendocrine tumours (NETs), that are visualized by different radiolabelled somatostatin analogues that bind 5 distinct somatostatin receptor types (named sstr1-5) that show different tissue distribution. The subtypes sstr2 and sstr5 are the most commonly expressed in NETs. Until now the most widely used radiolabelled somatostatin analogue for planar and single photon emission computed tomography (SPECT) has been [(111)In]pentetreotide, because of its commercial availability. Other analogues labelled with gamma emitting radionuclides are [(99m)Tc]EDDA/HYNIC-TOC, [(99m)Tc]P829, [(111)In]DOTA-lanreotide, [(111)In]DOTA-NOC-ATE, [(111)In]DOTA-BOC-ATE. However, these compounds have not been successful for the routine use. Moreover, NETs express various receptors that can be depicted by different radiopharmaceuticals, such as [(123)I]VIP and [(111)In]GLP-1. Besides this, some precursors of the catecholamines metabolism, as meta-iodo-benzyl-guanidine (MIBG), labelled with (123)I or (131)I, accumulates in neuroendocrine tissues, in particular those of sympathoadrenal lineage. MIBG scintigraphy is currently indicated for neuroblastoma, paraganglioma and phaeocromocitoma. An impressive technological progress has been achieved recently with PET and, in particular, with the development of hybrid instrumentations (PET/CT) combining nuclear imaging with radiological imaging providing both functional and morphologic information. Among positron emitting tracers, the [(18)F]FDG is the most diffuse in oncology, but other more effective tracers are available for NETs, such as the analogues labelled with 68Ga. The diagnostic sensitivity and accuracy of these technology is superior to that of gamma emitting radiopharmaceuticals, but the fact that they are not still registered limits their use in the clinical practice. This overview summarizes the state of art of NETs imaging, focusing the attention mainly on gamma-emitting tracers.
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PMID:Imaging of neuroendocrine tumours with gamma-emitting radiopharmaceuticals. 2016 82

Neuroendocrine tumours (NET) diagnosis has represented a major challenge in the past decades. The introduction of somatostatin receptor scintigraphy in the diagnostic work-up led to a significant improvement of accuracy. However with the advent of positron emission tomography (PET) that presents a higher spatial resolution as compared to the gamma camera and an array of different radiotracers, it is now possible to image NET with an even higher accuracy. In fact, PET imaging of NET is a rapidly evolving field closely connected to the development of novel beta-emitting radiopharmaceuticals. NET can be easily visualized on PET scans using an array of both metabolic and receptor-based tracers. [18F]DOPA and [68Ga]DOTA-peptides (DOTA-TOC, DOTA-NOC, DOTA-TATE) are very promising to image well differentiated NET and were reported to be superior to other imaging modalities (computed tomography [CT], somatostatin receptor scintigraphy). On the contrary, the role of [18F]FDG is limited in well differentiated NET, due to their low glucose metabolism and growth rate, while it still can provide valuable information in less differentiated tumours. On-going studies are investigating the potential role of new imaging agents (bombesin, GLP-1, CCK) that specifically bind to receptors expressed on NET cells.
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PMID:Imaging of NETs with PET radiopharmaceuticals. 2016 83

Fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) is utilized in more than 90% of cancers in staging, re-staging, assessing therapy response and during the follow-up. However, not all tumors show significant increase of metabolic activity on FDG-PET imaging. This is particularly true for prostate cancer, neuroendocrine tumors and hepatic tumors. In this review we have considered those already used for clinical applications such as 11C- and 18F-Choline, 11C-Methionine and 18F-FET, 18F-DOPA, 68Ga-DOTA-somatostatine analogues, 11C-Acetate and 18F-FLT. Choline presents a high affinity for malignant prostate tissue, even if low grade. Choline can be labeled with either 11C or 18F, the former being the preference due to lower urinary excretion and patients exposure. The latter is more useful for possible distribution to centers lacking in on-site cyclotron. Methionine is needed for protein synthesis and tumor cells require an external supply of methionine. These tracers have primarily been used for imaging of CNS neoplasms. The most appropriate indication is when conventional imaging procedures do not distinguish between edema, fibrosis or necrosis and disease relapse. In addition, the uptake of 11C-Methionine is proportional to the tumor grade and, therefore, the maximum small unilamellar vesicles (SUV) inside the brain mass before therapy is somehow considered a prognostic value. Neuroendocrine tumors (carcinoids, pheocromocytoma, neuroblastoma, medullary thyroid cancer, microcytoma, carotid glomus tumors, and melanoma) demonstrate an increased activity of L-DOPA decarboxylase, and hence they show a high uptake of 18FDOPA. For the study of NETs, 68Ga-DOTA-TOC/DOTA-NOC has been introduced as PET tracer. This compound for PET imaging has a high affinity for sst2 and sst5 and has been used in the detection of NETs in preliminary studies; 68Ga-DOTA-NOC PET is useful before metabolic radiotherapy in order to evaluate the biodistribution of the therapeutic compound; 18F-FLT is a specific marker of cell proliferation and the most important field of application of FLT is lung cancer. Other tracers are used in PET utilized as markers of hypoxia inside big neoplastic masses include 18F-MISO, 64Cu-ATSM, 18F-EF5, which highlight the presence of hypoxic areas are useful for patients that must be treated with radiotherapy.
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PMID:Non-FDG PET in the practice of oncology. 2044 72

Despite the considerable technological advances in imaging modalities which have occurred over the last years, EUS remains one of the most reliable and accurate technique for the study of gastroenteropancreatic neuroendocrine tumors. More specifically, EUS can detect very small lesions, assess the local extent and lymph node involvement and biopsy the lesion for cytophatological confirmation (EUS-FNA). In addition, nuclear medicine imaging has a relevant role in the evaluation of NET. However, its performance depends on series of patient-specific features (lesion size and uptake, depth and other anatomic features; metabolic activity, receptor expression, affinity and vacancy, tissue specificity) and technical features (choice of tracer, administered dose, and physical half-life; instrument sensitivity, acquisition technique, reader experience). In particular, current data show that PET/CT has greater intrinsic resolution and sensitivity than SPECT or SPECT/CT images resulting in improved tumor detection. However, the PET tracer of choice has not yet been identified. 18F-FDG has proved to be useful as indicator of tumor aggressiveness rather than detection of extent of disease, and 68Ga-DOTA-TOC has demonstrated good results in clinical trials. 11C-5HTP has performed well in limited trials, but the 20-min half life of 11C precludes widespread availability. Better information concerning biodistribution and further comparative data of these agent in larger clinical trials are warranted.
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PMID:Imaging techniques in diagnostic approaches. 2130 38

Somatostatin receptor scintigraphy is considered as a comprehensive imaging modality for many neuroendocrine tumors. Multiple radiotracers using combinations of gamma or positron emitting radionuclides and tracers are now available. Newer radiopharmaceuticals using (99m)Tc labeled with TOC, TATE, NOC are good alternatives to the 68 - Gallium radiotracers where the PET facility is not available. The pictoral depicts the role of SRS using 99m TC - HYNIC -TOC radiotracers in staging and treatment planning of NETs. Characterization of the tumor biology using combined SRS and FDG PET/CT is also demonstrated with a proposed categorization method. The emerging role of SRS in tailored targeted radionuclide therapy is outlined in brief.
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PMID:A pictoral review on somatostatin receptor scintigraphy in neuroendocrine tumors: The role of multimodality imaging with SRS and GLUT receptor imaging with FDG PET-CT. 2383 17

Pulmonary neuroendocrine tumors (pNETs) arise from bronchial mucosal cells known as enterochromaffin cells which are part of the diffuse neuroendocrine system. The pathological spectrum of pNETs ranges from low-/intermediate-grade neoplasms such as bronchial carcinoids (BCs), also known as typical or atypical carcinoids, to high-grade neoplasms as large-cell neuroendocrine carcinoma and small-cell lung cancer. The tumor biology of pNETs still represents a matter of open debate. The distinct features among the different pNETs include not only their pathologic characteristics but also their clinical behavior, epidemiology, treatment, and prognosis. In this sense, a correct pathological identification in the preoperative setting is a key element for planning the best strategy of care in pNETs and especially in BCs. Controversial results have been reported on the diagnostic accuracy of fluorine-18-fluorodeoxyglucose positron emission tomography or positron emission tomography/computed tomography (F-18-FDG PET or PET/CT) in BCs. On the other hand, there is increasing evidence supporting the use of PET with somatostatin analogues (DOTA-TOC, DOTA-NOC, or DOTA-TATE) labeled with gallium-68 (Ga-68) in pNETs. Herein, we review the pertinent literature aiming to better define the current state of art of PET/CT in the detection and histological differentiation of pNETs with special emphasis on BCs.
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PMID:PET/CT assessment of neuroendocrine tumors of the lung with special emphasis on bronchial carcinoids. 2485 Jan 79

This report describes a case of extensive diffuse bone marrow involvement with bilateral breast metastases from duodenal neuroendocrine tumor giving rise to a superscan-like appearance on somatostatin receptor-targeted (99m)Tc-hydrazinonicotinamide-TOC scintigraphy. The metastatic lesions demonstrated partial concordance with (18)F-FDG PET/CT findings, signifying varying tumor biology and heterogeneity among metastatic lesions in the same individual, as illustrated with a dual-tracer approach. There was a dramatic symptomatic and biochemical response and better health-related quality of life with a single fraction of peptide receptor radionuclide therapy with (177)Lu-DOTATATE, and radiologically there was stable disease at that point.
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PMID:The use of 99mTc-HYNIC-TOC and 18F-FDG PET/CT in the evaluation of duodenal neuroendocrine tumor with atypical and extensive metastasis responding dramatically to a single fraction of PRRT with 177Lu-DOTATATE. 2519 Jul 35


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