| 1. |
- Bergström, Mats, et al.
(författare)
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PET imaging of adrenal cortical tumors with the 11beta-hydroxylase tracer 11C-metomidate
- 2000
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 41:2, s. 275-282
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the study was to evaluate PET with the tracer 11C-metomidate as a method to identify adrenal cortical lesions.METHODS:PET with 11C-metomidate was performed in 15 patients with unilateral adrenal mass confirmed by CT. All patients subsequently underwent surgery, except 2 who underwent biopsy only. The lesions were histopathologically examined and diagnosed as adrenal cortical adenoma (n = 6; 3 nonfunctioning), adrenocortical carcinoma (n = 2), and nodular hyperplasia (n = 1). The remaining were noncortical lesions, including 1 pheochromocytoma, 1 myelolipoma, 2 adrenal cysts, and 2 metastases.RESULTS:All cortical lesions were easily identified because of exceedingly high uptake of 11C-metomidate, whereas the noncortical lesions showed very low uptake. High uptake was also seen in normal adrenal glands and in the stomach. The uptake was intermediate in the liver and low in other abdominal organs. Images obtained immediately after tracer injection displayed high uptake in the renal cortex and spleen. The tracer uptake in the cortical lesions increased throughout the examination. For quantitative evaluation of tracer binding in individual lesions, a model with the splenic radioactivity concentration assigned to represent nonspecific uptake was applied. Values derived with this method, however, did show the same specificity as the simpler standardized uptake value concept, with similar difference observed for cortical versus noncortical lesions.CONCLUSION:PET with 11C-metomidate has the potential to be an attractive method for the characterization of adrenal masses with the ability to discriminate lesions of adrenal cortical origin from noncortical lesions.
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| 2. |
- Bergström, Mats, et al.
(författare)
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PET with [11C]-Metomidate for the Visualization of Adrenocortical Tumors and Discrimination from Other Lesions
- 1999
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Ingår i: Clinical Positron Imaging. - 1095-0397 .- 1878-5751. ; 2:6, s. 339-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose:The purpose of the study was to evaluate the potential role of PET with the adrenocortical-specific tracer 11C-metomidate in the characterization of incidentally found adrenal cortical lesions and in adrenocortical carcinomas.Methods:PET with 11C-metomidate was performed in 15 patients with unilateral adrenal mass confirmed by CT (incidentalomas) and in 9 additional patients with adrenocortical cancer. All incidentalomas subsequently underwent surgery, except 2 subjected to biopsy only. These lesions were histopathologically examined and diagnosed as adrenal cortical adenoma (n = 6; 3 nonfunctioning), adrenocortical carcinoma (n = 2) and nodular hyperplasia (n = 1). The remaining were non-cortical lesions including 1 pheochromocytoma, 1 myelolipoma, 2 adrenal cysts, and 2 metastases.Results:All lesions, except 1, with an adrenocortical origin were easily identified due to exceedingly high uptake of 11C-metomidate, whereas the non-cortical lesions showed very low uptake. The 1 false negative was a cancer that at surgery was found to be extensively necrotic. High uptake was also seen in normal adrenal glands. The tracer uptake kinetics indicated trapping of the tracer in the cortical lesions. For quantitative evaluation of tracer binding in individual lesions, the simple SUV concept was found to be equally accurate as more elaborate kinetic analyses.Conclusion:The patients presented and altogether over 40 PET investigations have demonstrated 11C-metomidate to be an attractive tracer for the characterization of adrenal masses with the ability to discriminate lesions of adrenal cortical origin from non-cortical lesions. Additionally the method allows the assessment of metastases from adrenocortical cancers, and the very high contrast has allowed partial whole-body examinations.
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| 3. |
- Eriksson, Barbro, et al.
(författare)
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The role of PET in localization of neuroendocrine and adrenocortical tumors
- 2002
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923 .- 1749-6632. ; 970, s. 159-169
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Tidskriftsartikel (refereegranskat)abstract
- Positron emission tomography (PET) supplies a range of labeled compounds to be used for the characterization of tumor biochemistry. Some of these have proved to be of value for clinical diagnosis, treatment follow up, and clinical research. The first routinely used PET tracer in oncology, 18F-labeled deoxyglucose (FDG), was successfully used for diagnosis of cancer, reflecting increased expression of glucose transporter in cancerous tissue. This tracer, however, usually does not show sufficient uptake in well-differentiated tumors such as neuroendocrine tumors. We developed a tracer more specific to neuroendocrine tumors—the serotonin precursor 5-hydroxytryptophan (5-HTP) labeled with 11C—and demonstrated increased uptake and irreversible trapping of this tracer in carcinoid tumors. The uptake was so selective and the resolution was so high that we could detect more liver and lymph node metastases with PET than with CT or octreotide scintigraphy. To further improve the method, especially to reduce the high renal excretion of the tracer producing streaky artifacts in the area of interest, we introduced premedication by the decarboxylase inhibitor carbidopa, leading to a six-fold decreased renal excretion while the tumor uptake increased three-fold, hence improving the visualization of the tumors.11C-labeled l-DOPA was evaluated as an alternative tracer, especially for endocrine pancreatic tumors, which usually do not demonstrate enhanced urinary serotonin metabolites. However, only half of the EPTs, mainly functioning tumors, could be detected with l-DOPA. Instead 5-HTP seems to be a universal tracer for EPT and foregut carcinoids. With new, more sensitive PET cameras, larger field of view and procedures for whole-body coverage, the PET examination with 5-HTP is now routinely performed as reduced whole-body PET examinations with coverage of the thorax and abdomen. With this method we have been able to visualize small neuroendocrine lesions in the pancreas and thorax (e.g., ACTH-producing bronchial carcinoids) not detectable by any other method, including octreotide scintigraphy, MRI, and CT. Another tracer, the 11β-hydroxylase inhibitor, metomidate labeled with 11C, was developed to simplify diagnosis and follow-up of patients with incidentalomas. A large series of patients with incidentally found adrenal masses have been investigated and so far all lesions of adrenocortical origin have been easily identified because of exceedingly high uptake of 11C-metomidate, whereas noncortical lesions showed very low uptake. In addition, adrenocortical cancer shows high uptake, suggesting that this PET tracer can be used for staging purposes.
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| 6. |
- Örlefors, Håkan, et al.
(författare)
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Whole-body 11C-5-hydroxytryptophan positron emission tomography as a universal imaging technique for neuroendocrine tumors : Comparison with somatostatin receptor scintigraphy and computed tomography
- 2005
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 90:6, s. 3392-3400
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Tidskriftsartikel (refereegranskat)abstract
- Neuroendocrine tumors (NETs) can be small and situated almost anywhere throughout the body. Our objective was to investigate whether whole-body (WB) positron emission tomography (PET) with 11C-5-hydroxytryptophan (5-HTP) can be used as a universal imaging technique for NETs and to compare this technique with established imaging methods. Forty-two consecutive patients with evidence of NET and a detected lesion on any conventional imaging (six bronchial, two foregut, 16 midgut, and two thymic carcinoids; one ectopic Cushing’s syndrome; four gastrinomas; one insulinoma; six nonfunctioning endocrine pancreatic tumors; one gastric carcinoid, one paraganglioma; and two endocrine-differentiated pancreatic carcinomas) were studied. The WB-11C-5-HTP-PET examinations were compared with WB-computed tomography (CT) and somatostatin receptor scintigraphy (SRS). Tumor lesions were imaged with PET in 95% of the patients. In 58% of the patients, PET could detect more lesions than SRS and CT and equal numbers in 34%, whereas in three cases, SRS or CT showed more lesions. In 84% (16 of 19 patients), PET could visualize the primary tumor compared with 47 and 42% for SRS and CT, respectively. The surgically removed PET-positive primary tumor sizes were 6–30 mm. To conclude, this study indicates that WB-11C-5-HTP-PET can be used as a universal imaging method for detection of NETs. This study also shows that WB-11C-HTP-PET is sensitive in imaging small NET lesions, such as primary tumors, and can in a majority of cases image significantly more tumor lesions than SRS and CT.
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