Key words

IJNM

Indian Journal of Nuclear Medicine

0972-3919

Society of Nuclear Medicine, India

ijnm-22-4-091

RESEARCH ARTICLE

Reducing the time for ¹⁸F-FDG synthesis

Rajan

M G R

Nandy

S K

Soni

P S

Medical Cyclotron Facility, BRIT/BARC, Laboratory Nuclear Medicine Section, BARC, Mumbai.

122007

224

Key wordsShort SynthesisHPLCAlkali Hydrolysis

Aims

¹⁸F-FDG is the most widely used PET-Radiopharma⁻ceutical and is produced and used world-wide using indigenous and commercially available equipment. The time taken for synthesis, from the time the radioactivity comes into the synthesis-module till it is delivered into the dispenser, varies widely-from 50 min in the older machines to 35 minutes in the newer ones. A recently introduced cassette based synthesis procedure is reported to take 22 minutes. All of them invariably use the procedure described by Hamacher in the 1980’s with little modifications.

Materials and Results

We are using the Nuclear-interface FDG synthesis module (now known as GE Tracer lab FX) with a programmed time-list of 35 min. Considering the short 110 min T½ of ¹⁸F, it is logical to reduce the synthesis time without affecting the yield as this will save on the ¹⁸F-lost due to decay and make the PET-radiopharmaceutical available to users earlier. We critically analyzed the various processes in the synthesis, closely looking at the various distillation/drying steps, the nucleophilic substitution and hydrolysis kinetics and have been able to reduce the overall process to 21min. This results in a saving of about 10% of the ¹⁸F-FDG, which is significant. Presently, the yield obtained, without decay correction was 46.8±1.4% from five trial batches starting with ~3700 MBq of ¹⁸F. Considering a saving of 14 min in synthesis time, this works out to an effective yield of ~55%. Work is underway to improve this.

The quality of the synthesized FDG is identical with that produced by the longer process as confirmed by TLC in MeCN: H2O (95:5) and further cross-checked by analytical HPLC using Nucleosil NH2 column with 95:5 MeCN: H2O solvent coupled with radioactivity as well as UV detector.

Conclusion

The product fulfills the pharmacopoeia criteria and all batches have passed endotoxin and sterility tests. Residual solvent levels are also within permissible limits.

Reducing the time for 18F-FDG synthesis

Keywords

Reducing the time for ¹⁸F-FDG synthesis