Importance of ¹⁸F-FDG

● The most widely used PET radiopharmaceutical ¹⁸F-FDG is similar in structure to glucose, this compound is used in PET due to the ubiquitous use of glucose by the human body.
● FDG is labeled with ¹⁸F, a cyclotron produced radioisotope with a half life of approximately 110 minutes.

Preparation of ¹⁸F-FDG

● 18F-FDG: Mechanism of Uptake

• Called metabolic trapping
• Tumors have higher metabolic rate than normal tissue.
• Structures of FDG and glucose are similar enough for there to be uptake, but different enough that metabolism can not take place
  
  

 

Preparation of ¹⁸F-FDG

1. Synthesis is based on the nucleophilic substitution with ¹⁸F -, promoted by a phase transfer catalyst.
2. The process includes the separation of the ¹⁸O from the ¹⁸F, labeling reaction, hydrolysis and finally formulation as an injectable solution.
3. Process time is < 30 min.
4. The radiochemical yield is 50 to 60 % depending on purity of starting material
5. The specific activity is >10 Ci/μmol (370 GBq/μmol)
6. The radiochemical purity is > 98.5 %.