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- Ahlström, Håkan, et al.
(författare)
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Pancreatic neuroendocrine tumors : diagnosis with PET
- 1995
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Ingår i: Radiology. - 0033-8419 .- 1527-1315. ; 195:2, s. 333-337
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To evaluate the use of carbon-11-labeled L-dihydroxyphenylalanine (L-DOPA) and hydroxytryptophan (5-HTP) in the diagnosis of pancreatic endocrine tumors with positron emission tomography (PET). MATERIALS AND METHODS: Twenty-two consecutive patients with clinically and biochemically verified pancreatic endocrine tumors were examined with computed tomography (CT) and PET with L-DOPA alone (n = 16) or both C-11-L-DOPA and C-11-5-HTP (n = 6). RESULTS: Tumor uptake of L-DOPA was found in 11 patients, eight of whom had metastatic disease. Heterogeneity of tracer uptake was noted among different lesions in the same patient (ie, high uptake in some lesions and low uptake in others). Results in patients examined with both L-DOPA and 5-HTP correlated well, but the uptake levels of 5-HTP were higher in two of three patients with positive findings. In two additional patients, CT enabled detection of tumors not detected at PET. CONCLUSION: The current PET technique can be a valuable complement to CT in demonstration of functional pancreatic endocrine tumors, in particular, glucagonomas, but is less useful in detection of nonfunctional tumors.
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| 6. |
- Bergström, Mats, et al.
(författare)
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In vivo demonstration of enzyme activity in endocrine pancreatic tumors : decarboxylation of carbon-11-DOPA to carbon-11-dopamine
- 1996
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 37:1, s. 32-37
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Tidskriftsartikel (refereegranskat)abstract
- METHODS:We used PET to characterize the uptake and decarboxylation of 11C-L-DOPA in vivo in two patients with endocrine pancreatic tumors: one glucagonoma and one gastrinoma.RESULTS:With L-DOPA labeled with 11C in the beta position, in which the radioactive label follows the molecule through decarboxylation to dopamine, significant uptake was observed in the tumors. With L-DOPA labeled in the carboxyl group, in which the label is rapidly eliminated from the tissue as 11CO2 if decarboxylation takes place, an almost complete lack of uptake is noted.CONCLUSION:This study shows that, using selective position labeling, an in vivo action of enzymatic activity can be observed with PET and that significant decarboxylation occurs in the tested endocrine pancreatic tumors. Also, marked retention of radioactivity occurs after treatment with somatostatin analogs. It is hypothesized that this is a reflection of a reduction of exocytosis which is induced by this treatment.
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| 7. |
- Bergström, Mats, et al.
(författare)
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Modulation of organ uptake of 11C-labelled L-DOPA
- 1997
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Ingår i: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 24, s. 15-
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Tidskriftsartikel (refereegranskat)abstract
- The present study was undertaken to investigate if pretreatment with pharmacological agents could change the organ uptake of 11C-labelled L-DOPA, and especially if the urinary excretion could be decreased. L-[beta-11C]DOPA was injected IV into unanesthetized Sprague-Dawley rats. After 20 min the rats were decapitated and organs taken out for radioactivity measurements. The uptake in the organs was investigated in animals only given the tracer, and in animals pretreated with drugs such as decarboxylase inhibitors carbidopa and benserazide as well as the monoamine oxidase inhibitors deprenyl, clorgyline, and the COMT inhibitor OR-486. A marked decrease in the urinary radioactivity was observed after carbidopa and benserazide administration. HPLC analysis revealed that under native conditions the major part of urinary radioactivity existed as dopamine, which was eliminated by the decarboxylase inhibitors. After pretreatment with the COMT inhibitor OR-486, the radioactivity uptake in the pancreas increased fourfold as compared to non-treated animals. HPLC analysis showed that this correlated with a marked increase in radiolabelled DOPAC. In the other organs and with the other drugs, only small effects were observed. With L-[beta-11C]fluoroDOPA as a tracer, similar results were observed although the increase in the pancreas by OR-486 had a lower magnitude. These studies suggest that it might be possible to improve the diagnostic ratio of L-[beta-11C]DOPA or L-[18F]fluoroDOPA in whole-body PET studies by pretreating the patient with decarboxylase inhibitor for reducing the urinary excretion and potentially increase the target organ uptake by COMT inhibition.
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| 8. |
- 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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- Edgren, M, et al.
(författare)
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Biological characteristics of adrenocortical carcinoma : A study of p53, IGF, EGF-r, Ki-67 and PCNA in 17 adrenocortical carcinomas
- 1997
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 17:2B, s. 1303-1310
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Tidskriftsartikel (refereegranskat)abstract
- Adrenocortical carcinoma (ACC) is a rare neoplasm with a poor prognosis. Prognostic factors are needed to identify patients who should be treated aggressively and those for which a less aggressive approach is warranted. As a result of advances within the field of immunohistochemistry, investigations of Ki-67, PCNA, IGF, EGF-r and p53 were performed in 17 ACC. The aim of this study was to clarify the role of Ki-67, PCNA, EGF-r, IGF and p53 in correlation to tumour behaviour and outcome. This retrospective study includes 16 patients, 10 women and 6 men, with a median age of 46 years. Nine tumours were hormonally functioning and 7 were non-functioning. The results obtained revealed that all tumours expressed PCNA and Ki-67 with median values of 59% and 14%, respectively, while p53 was negative in 88%, IGF negative in 82% and EGF-r positive in 94% of the tumours. No correlation was found between p53, IGF, EGF-r and survival rate. There was no interdependence between PCNA and Ki-67, or between PCNA, Ki-67 and the survival rate.
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