No abstract available

[en] The usefulness of [1-11C]acetate as a tracer of overall myocardial oxidative metabolism for use with positron emission tomography has been investigated in 12 closed-chest dogs. Myocardial 11C activity clearance kinetics after intravenous administration of [1-11C]acetate in dogs have been determined noninvasively by positron emission tomography. Biexponential fitting of regional myocardial 11C time-activity curves was performed to give clearance half-times and fractional distribution. The rate constant k1 for the early rapid phase of 11C activity clearance was found to correlate linearly with myocardial oxygen consumption (y = 0.0156x + 0.039; SEE = 0.023; r = 0.95). k1 was approximately 7% lower in septal sectors compared with the left ventricular free wall, suggesting that regional oxygen consumption in the septum was lower; a concomitant regional attenuation of blood flow in the septum relative to the left ventricular free wall was also observed. In dogs using carbohydrates as the predominant fuel, k1 oxygen consumption was somewhat more than in dogs using predominantly free fatty acids (0.021 +/- 0.002 compared with 0.018 +/- 0.002, p less than 0.01), indicating that increased carbohydrate consumption is associated with a small increase in k1 at constant oxygen consumption. It is concluded that measurement of myocardial [1-11C]acetate kinetics allows noninvasive determination of cardiac oxygen consumption by positron emission tomography and that the technique is relatively insensitive to myocardial fuel selection

[en] Short communication

[en] Since 1998, routine [¹⁸F]FDG syntheses are being carried out by alkaline hydrolysis on a solid support, i.e. the labeled intermediate is trapped on a tC18 solid phase extraction cartridge, purified and finally hydrolyzed within the cartridge, at room temperature, using sodium hydroxide. The present study demonstrated that no epimerization of [¹⁸F]FDG to [¹⁸F]FDM occurs even when 12 N NaOH is used and when the hydrolysis time is extended up to 1 h. The alkaline hydrolysis on solid support appears to be a simple method leading to [¹⁸F]FDG with high purity

[en] The reaction of methyl 4,6-O-benzylidene-3-O-benzyl-2-O- trifluoromethanesulfonyl-β-D-glucopyranoside in acetonitrile at 75⁰ for 30 min with [/sup 18/F]tetra-n-butylammonium fluoride, followed by silica gel column purification (di-chloromethane: acetone, 95:5) gave the corresponding [/sup 18/F] methyl 4,6-O-benzylidene-3-O-benzyl- 2-fluoro- β -D-mannopyranoside with complete regio- and stereoselectivity (42% radiochemical yield). Hydrolysis of the radiolabeled fluoromannopyranoside intermediate with either 6N HCl or 50% methanesulfonic acid for 30 min at reflux, followed by purification by column chromatography (ion retardation, AG11A8 resin and neutral alumina) gave pure [/sup 18/F]2-deoxy-2-fluoro-D-mannose ([/sup 18/F] 2-FDM) suitable for human injection with a total radiochemical yield (from [/sup 18/F] fluoride ion) of 34%. Since chromatographic identification of 2-fluorodeoxyhexoses does not necessarily constitute a proof of chemical structure, unequivocal evidence of the identity of the final product was obtained using Fourier transform /sup 19/F-NMR. Samples with sufficient fluorine 19 mass when analyzed using /sup 19/F-NMR spectroscopy [Bruker WM-500, 470.56 MHz] after F-18 decay, showed only two peaks corresponding to the two anomers of 2-FDM (α=38.16, β=56.56; D/sub 2/O, solvent; C/sub 6/F/sub 6/, external reference; proton decoupled). The synthetic procedure described here permits the routine preparation of large amounts of [/sup 18/F]/sub 2/-FDM for tomographic studies. In this manner, comparisons of the biological and kinetic behavior of epimerically pure [/sup 18/F]2-deoxy-2-fluoro-D-glucose ([/sup 18/F]2-FDG) and [/sup 18/F]2-FDM in humans are now possible

[en] The aim of the present work was to develop a simple, high yield synthesis of a F-18 labeled neuroleptic ligand. We report a new class of F-18 labeled neuroleptic ligands, as exemplified by 3-(2'-[F-18]fluoroethyl)spiperone (FESP), with attractive properties for dynamic characterization of dopamine receptor binding in living primates with PET. (author)

[en] We describe herein a simple, high yield synthesis of 6-fluorodopa (3) based on regioselective fluorodemercuration (6) of afforded pure 3. Extension of this procedure to radiofluorination with [F-18]AcOF yielded 6-[F-18]fluorodopa with >98% chemical and radiochemical purity. Thus, multimillicurie amounts of pure 6-[F-18]-fluorodopa for tomographic studies are now routinely available. (author)

[en] To further validate its use in positron emission tomography (PET), we studied the binding of [¹⁸F]altanserin, a specific 5HT₂ radioligand, in the rat brain using in vivo autoradiography. Distribution of [¹⁸F]altanserin binding was comparable to the in vitro mapping of 5HT₂ receptors reported in the literature. Selective displacers were used to test the reversibility and the selectivity of this radioligand. Specific binding of [¹⁸F]altanserin in the rat frontal cortex was quantified by direct counting with an electronic imaging system and by quantification on digitalized autoradiograms. Close results of about 30 pmol/g were obtained with both methods. Our data confirmed that [¹⁸F]altanserin is a valid tracer for 5HT₅ receptors binding studies

[en] Complete text of publication follows. Dear Sir, We read with interest the [¹⁸F]FDG review, recently published in the Journal of Radioanalytical Nuclear Chemistry, relating the most important aspects of [¹⁸F]FDG production over the last 40 years [1]. However, we would like to add some comments and to mention some references which did not appear in the bibliography of this publication though our lab's work is well implemented in several synthesizers from the market used for the routine synthesis of this radiopharmaceutical. 1. As stated by the authors, Hamacher's nucleophilic approach is undoubtedly the [¹⁸F]FDG method on which most of the current automated synthesis modules are based [2]. This original [¹⁸F]FDG process was reported in 1986 by the Julich group and some modification were implemented later to improve the radiochemical yield (RCY). For example, a basic hydrolysis in liquid phase rather than with HCl has been proposed by Fuchtner et al. [3]. In 1997, our laboratory presented at the XIIth International Symposium on Radiopharmaceutical, a synthetic approach that combines the two procedures and which overcome the disadvantages of the acid and basic aqueous methods [4]. In the CRC process, the first labelling step is performed classically according to the Hamacher's method. After labelling, the crude 2-[¹⁸F]fluoro-1,3,4,6-tetra-O-acetyl-D-glucose ([¹⁸F]FTAG) is trapped on a ^tC18 solid phase extraction (SPE) cartridge. In a second step, the removal of the acetyl protecting groups of the [¹⁸F]FTAG is performed by basic hydrolysis on this solid phase support (^tC18) [4,5,6]. The main advantages of the CRC approach is that the [¹⁸F]FTAG is not eluted from the SPE but kept on it and the hydrolysis reaction conducted on this ^tC18 cartridge. This basic hydrolysis on the solid phase is faster (90s) than in solution and proceeds at room temperature, without any [¹⁸F]FDG epimerization [7, 8] what greatly facilitates the automation of the process (no second evaporation is required for solvent removal and no additional heating is required). After acidification, the very near to neutral solution eluted from the ^tC18 support allows the use of a buffer solution rather than a cation exchange or a retardation resin to afford the final isotonic solution. Therefore, the organic resins of the other methods for which microbial controls were not very easy to realize were discarded. As a result, in addition to the ^tC18 hydrolysis SPE, the other cartridges of the process are a Sep-Pak Accell Plus QMA™ (silica-based anion exchanger from Waters) for the [¹⁸F]fluoride recovery and a ^tC18/alumina for the final purification (see details in the paper [5]). All these chemistry improvements have greatly simplified the hardware and the software, decreased the duration of the synthesis and opened the way to the first GMP synthesis of [¹⁸F]FDG. This patented hydrolysis method [9] was firstly fully automated with a disposable kit assembly made of standard commercially available single-use components and the FDG synthesizer from Coincidence Technologies (in use for routine production, since September 1998, in our Cyclotron Research Centre) [5, 6, 9], the TRACERlab MX™ from GE Medical Systems and the FASTlab™ module of GE Healthcare. Up until now, this synthesis is still largely used in the world for the [¹⁸F]FDG preparation. Moreover this approach is now also implemented on other synthesizers from the market [i.e., AIO (Trasis)]. 2. We would like also to draw your attention on the following point: even if the author's claim that the presence of the [¹⁸F]FDM (2-deoxy-2-[¹⁸F]fluoro-D-mannose) has to be evaluated after basic hydrolysis, the review reports only papers where the stability of [¹⁸F]FDG towards epimerization is investigated in liquid phase. In 2001, we demonstrated that no epimerization of [¹⁸F]FDG to [¹⁸F]FDM occurs on the solid phase support under standard routine conditions [i.e. 2 min, room temperature and NaOH (2 N)] and even with NaOH (12 M) and hydrolysis duration extended up to one hour [7, 8]. 3. The table 1 of the review lists the commercial modules, grouped by type, with the synthesis duration and radiochemical yields at the end of synthesis (EOS). For information, the first commercial module with cassette and reagent kit was the Coincidence module from JL Morelle (1997) developed in collaboration with the CRC/ULg. After the acquisition of Coincidence by GE in October 2001, the FDG Coincidence module was renamed TRACERlab MX™ in mid-2002. We think that the work carried out in our laboratory, briefly summarized in this letter, and more in details in the following papers [5, 8] was at the origin of the state-of-the-art automation for the GMP synthesis of [¹⁸F]FDG. With best regards, Yours sincerely, C. Lemaire, A Luxen. (author)

[en] During the past decade, microwave technology has received considerable attention in organic synthesis and in radiochemistry primarily due to substantial rate increase and time gain. Most of the examples described are reactions done with domestic microwave ovens. Space and shielding requirements, difficulties in integrating them in an automated synthesis system, and poor reproducibility were the major concerns for their use in radiochemistry. The authors describe their microwave cavity system and present potential applications for labelling with nucleophilic [¹⁸F]fluoride. [¹⁸F]FDG and [¹⁸F]altanserin synthesis are discussed in terms of radiochemical yields, synthesis time, and reliability