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- 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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- Lindner, Karl-Johan, et al.
(författare)
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Analysis of l-[methyl-11C]methionine and metabolites in human plasma by an automated solid-phase extraction and a high-performance liquid chromatographic procedure
- 1996
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Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1387-2273 .- 1878-5603. ; 679:1-2, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- A fully automated method for separation of l-[methyl-11C]Methionine from metabolites in patient plasma was developed. l-[methyl-11C]Methionine was isolated from plasma by solid-phase extraction (SPE). The radioactivity retained on the SPE column was eluted and injected onto the HPLC system for separation of in vivo formed l-[methyl-11C]methionine radiolabeled metabolites. The yield through the isolation procedure and HPLC analysis was greater than 95% with a precision better than 5% (R.S.D.). The calculated rate of l-[methyl-11C]methionine transport into tumor tissue was markedly different with and without compensation for radiolabeled metabolises in patient plasma.
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- Sundin, Anders, et al.
(författare)
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PET and parathyroid L-[carbon-11]methionine accumulation in hyperparathyroidism
- 1996
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 37:11, s. 1766-1170
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Tidskriftsartikel (refereegranskat)abstract
- The study was designed to characterize L-[methyl-11 C]methionine accumulation in abnormal parathyroid tissues of hyperparathyroidism (HPT).METHODS:Thirty-four patients with primary (n = 32) or secondary HPT were investigated with PET before primary or reoperative (n = 25) parathyroid surgery. Parathyroid 11C-methionine accumulation was analyzed for integrated uptake values in defined tissue volumes standardized for the injected dose and body weight (SUV), four contiguous pixels of maximal accumulation (SUVhs), SUV multiplied by area of region of interest (SUVr) and by the excised tissue weight (SUVw). Transport rate constants (slope, slopehs) were calculated according to Patlak's formula using plasma 11C activity corrected for 11C-methionine metabolites.RESULTS:True-positive localization was achieved in 85% of patients in whom 81% of the excised parathyroid lesions were visualized; no false-positive results were obtained. Corresponding proportions were 59% and 57% for CT and 55% and 52% for ultrasound, respectively. In the true-positive cases, parathyroid SUV, SUVhs and transport rate constants were consistently higher (p < 0.01) than in the thyroid, pharynx-esophagus, neck muscle and apical lung. Parathyroid SUV, SUVhs and SUVr increased with intact serum parathyroid hormone and calcium values (p = 0.0001-0.031), and weight of the excised tissue correlated with SUV and SUVhs (p = 0.024, 0.044). Parathyroid SUVhs varied strongly with the transport rate constants (p = 0.0008), and SUVr as well as s-calcium values differed significantly between parathyroid adenomas (n = 11), chief cell hyperplasias (n = 13), inadvertent implants (n = 3) and parathyroid cancers (n = 3).CONCLUSION:Carbon-11-methionine PET has potential application in preoperative localization and metabolic characterization of abnormal parathyroid tissues in human HPT.
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