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INTRODUCTION: [18F]Fluoromethylcholine ([18F]FCH) is a potent tumors imaging agent. In order to fulfill the demand of pre-clinical and clinical studies, we have developed an automated high yield one-pot synthesis of this potent tumors imaging agent. METHODS: [18F]FCH was synthesized using a modified TRACERlab FxFN module. Briefly, dibromomethane (10% in CH3CN) was fluorinated with K[18F]/K 2.2.2 in a glassy carbon reaction vessel at 120°C for about 5min to generate [18F]fluorobromomethane ([18F]FBM). The resulting [18F]FBM was then bubbling (He, 700mL/min) through four Sep-Pak® Silica Plus Long cartridges to react with dimethylaminoethanol (10% DMAE in 0.3mL DMSO) which was pre-loaded on Sep-Pak® C18 Plus Short cartridge. The [18F]FCH was purified by solid-phase extraction (SPE) using one Sep-Pak® C18 Plus Short and one Sep-Pak® CM Plus Short in series. The quality of [18F]FCH synthesized by this method was verified by HPLC and TLC as compared to authentic sample. RESULTS: Using this improved one-pot method, the RCY of [18F]FCH was 18.8 ± 2.1% (EOB, n = 27) in a synthesis time of 49 ± 5min from EOB. The radiochemical purity of [18F]FCH was greater than 90% and the residual DMAE concentration in the final product was less than 10ppm. CONCLUSIONS: This optimized method could fulfill the demand of [18F]FCH for both pre-clinical and clinical studies, especially for nearby study sites without a cyclotron.
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AIM: 99mTc-HL91 is a new hypoxia agent and can identify acutely ischaemic viable myocardium in a canine model using a standard gamma camera. The purpose of the study was to determine whether this tracer could be used to detect regional ischaemia in chronic ischaemic myocardium in a swine model. METHOD: Using a porcine model of chronic myocardial ischaemia, five mini-pigs with proximal left anterior descending artery (LAD) stenoses were studied. Injection of 462.5 MBq (12.5 mCi) 99mTc-HL91 was followed by imaging over 2 h. Coronary angiography and dipyridamole stress-re-injection 201Tl single photon emission computed tomography (SPECT) were performed within 1 day of each other. RESULTS: None of the five pigs demonstrated positive hot 99mTc-HL91 uptake throughout the 2 h imaging, whereas four of the five animals showed significant myocardial ischaemia on 201Tl SPECT. The region of interest analysis of LAD/left circumflex artery count ratios at 1 and 2 h demonstrated similar 99mTc-HL91 uptake and retention in chronic ischaemic as well as non-ischaemic myocardium. CONCLUSION: 99mTc-HL91 is inferior to 201Tl in scintigraphic detection of chronic myocardial ischaemia.