Dean Jolly

New high-yield synthesis of 18F-labelled 2-deoxy-2-fluoro-D-glucose

A new high-yield synthesis for the production of 18F-2-FDG has been developed by reacting 18F-labelled acetyl hypofluorite, prepared by in situ reaction of 18F-molecular fluorine with sodium acetate in glacial acetic acid, and tri-acetyl-D-glucal at room temperature. Molecular fluorine labelled with 18F was produced by a 20Ne(d, alpha) 18F reaction. 1,3,4,6-tri-O-acetyl-2-deoxy-2-fluoro-D-glucopyranose is extracted with methylene chloride, evaporated to dryness and hydrolyzed, yielding 98% radiochemically pure 18F-2-FDG. Overall radiochemical yield is about 24 +/- 3%. The specific activity of the final product at the end of synthesis is about 25.38 GBq/mmol (685 mCi/mmol). The synthesis time is approximately 60 min. The synthesis proves that small medical cyclotrons are able to produce 18F-molecular fluorine at the levels needed for the synthesis of 18F-2-FDG used in functional imaging with positron emission tomography.

Multimodal microglia imaging of fiber tracts in acute subcortical stroke

Case series with 11C‐PK11195 and positron emission tomography (PET) in stroke patients suggest that activated microglia may be detected in remote brain regions with fiber tract connections to the lesion site as an indicator of poststroke neuroinflammation. However, the specificity of these imaging findings remains to be demonstrated.

Improved work-up procedure for the production of [18F] flumazenil and first results of its use with a high-resolution research tomograph in human stroke

INTRODUCTION The central benzodiazepine receptor (cBZR)-gamma-aminobutyric acid (GABA(A)) receptor complex in the human brain plays an important role in many neurological and psychiatric disorders. (18)F-Labeled flumazenil ([(18)F]FZ) provides a potentially useful tracer to investigate those disorders by means of positron emission tomography (PET). METHODS [(18)F]Flumazenil was synthesized from its nitro-precursor Ro 15-2344 in DMF at high temperatures between 150 degrees C and 160 degrees C. Other solvents like acetonitrile and dimethylsulfoxide were also investigated as reaction media. A new HPLC method for the final purification of [(18)F]FZ was developed to circumvent some difficulties associated with a previously published procedure sometimes led to a contamination of [(18)F]FZ with Ro 15-2344. The final purification of the radiotracer was achieved using a Waters Symmetry Prep C18 HPLC column with elution with 0.05 M sodium acetate (NaOAc) buffer (pH 5)/THF/MeOH (80:10:10). RESULTS [(18)F]FZ could be synthesized in reproducible radiochemical yields (RCYs) of 15-20% (decay corrected to EOB) after 80 min overall synthesis time. The synthesized [(18)F]FZ was applied for the first time in a human PET study in a patient with ischemic right middle cerebral artery stroke using the HRRT high-resolution research scanner (Siemens Medical Solution, Knoxville, TN, USA). CONCLUSIONS [(18)F]FZ is a potentially useful GABA receptor-binding PET ligand. A modified procedure for its preparation in reproducibly high radiochemical yields has been described and the [(18)F]FZ thus produced has been used successfully in a pilot clinical study.

Metabolism and blood-brain clearance of l-3,4-dihydroxy-[3H]phenylalanine ([3H]DOPA) and 6-[18F]fluoro-l-DOPA in the rat

6-[18F]fluoro-L-DOPA (FDOPA) has been used as a tracer for the cerebral activity of L-3,4-dihydroxyphenylalanine (DOPA)-decarboxylase in studies of positron emission tomography (PET). However, the substitution of fluorine on the aromatic ring may alter the disposition and metabolism of FDOPA from that of endogenous DOPA. In the present study, the kinetics of the peripheral metabolism and the facilitated unidirectional blood-brain clearance of [3H]DOPA and FDOPA were compared in Wistar rats pretreated with carbidopa. In arterial plasma, FDOPA was O-methylated with an apparent rate constant (0.031 min-1) 3-fold that of [3H]DOPA in the same rats. The O-methylated metabolite of FDOPA (OMe-FDOPA) was eliminated from plasma at a rate constant (0.018 min-1) 3-fold that of OMe-[3H]DOPA. The mean unidirectional blood-brain clearance of FDOPA (4.5 mL.hg-1.min-1) in six brain regions was 60% higher than that of [3H]DOPA.

Synthesis of 2-deoxy-2-fluorohexoses by fluorination of glycals in aqueous media☆

Abstract 1,5-Anhydro-2-deoxy- d - arabino - ( d -glucal), 1,5-anhydro-2-deoxy- d - lyxo - ( d -galactal), and 3,4,6-tri- O -acetyl-1,5-anhydro-2-deoxy- d - lyxo -hex-1-enitol (3,4,6-tri- O -acetyl- d -galactal) ( 3 ) were fluorinated in water and organic solvent-water with molecular fluorine and, for 18 F-labelled compounds, with [ 18 F]fluorine. Chemical yields of 40 and 10% were obtained for 2-deoxy-2-fluoro- d -glucose and 2-deoxy-2-fluoro- d -mannose, respectively, and 35 and 5% for 2-deoxy-2-fluoro- d -galactose ( 12 ) and 2-deoxy-2-fluoro- d -talose ( 13 ), respectively. In the fluorination of 3 , the chemical yields of 12 and 13 were 38 and 6%, respectively. An l.c. separation of 2-deoxy-2-fluoro- d -hexoses is described.

New Synthesis of 2-Deoxy-2-fluoro-D-hexoses by Fluorination in Water

Abstract Interest in fluorinated sugars labelled with {18F} positron-emitting radionuclides as tracers for the measurement of glucose utilization in man by positron emission tomography1 (PET) and in animals by autoradiography2 has resulted in the development of numerous syntheses3-11 of 2-deoxy-2-fluoro-D-glucose (3a). Some of these syntheses are not practical because the carbohydrate substrates for the fluorination reactions are not readily available.

An on-line synthesis of “no-carrier-added” [11C]phosgene

Abstract A true on-line synthesis of “no-carrier-added” [11C]phosgene by u. v.-irradiation of a 11CO and Cl2 mixture in a continuous flow-mode is described. The maximum specific activity achieved in this work is 1.48 TBq/mmol (40 Ci/mmol) for [11C]phosgene measured via diphenyl urea.

Automated radiosynthesis of N-succinimidyl 3-(di-tert-butyl[18F]fluorosilyl)benzoate ([18F]SiFB) for peptides and proteins radiolabeling for positron emission tomography

Recently, silicon fluoride building blocks (SiFA) have emerged as valuable and promising tools to overcome challenges in the labeling of peptides and proteins for positron emission tomography (PET). Herein, we report a fully automated synthesis of N-succinimidyl 3-(di-tert-butyl[(18)F]fluorosilyl)benzoate ([(18)F]SiFB) by a commercially available Scintomics Hot Box 3 synthesis module, to be used as a prosthetic group for peptide and protein labeling. The drying of K2.2.2./K (18)F complex was performed according to the Munich method modified by our group (avoiding azeotropic drying) using oxalic acid to neutralize the base from the (18)F(-) containing QMA eluent. This K2.2.2./K (18)F complex was then used for SiFA (18)F-(19)F isotopic exchange followed by a fast purification by a solid-phase-extraction (SPE) to afford [(18)F]SiFB with an average preparative radiochemical yield (RCY) of 24±1% (non-decay corrected (NDC)) within a synthesis time of 30 min. The [(18)F]SiFB produced by automated synthesis was then used for the (18)F-labeling of rat serum albumin (RSA) as a proof of applicability.