Positron emission tomography (PET) is the most sensitive imaging technology in nuclear medicine to measure biological and physiological process in vivo, with many applications in clinical areas such as oncology, neuropsychiatry and cardiology. The most common radionuclides for the production of radiopharmaceuticals are 11C, 13N, 14O and 18F, which are easily introduced in biomolecules. Of them 18F is the most used positron emitting radionuclides because of its half-life of 110 min which makes it suitable for more complexes synthetic strategies. As a matter of facts, the development of appropriate synthetic methods is one of the most challenges in radiochemistry. The introduction of 18F into the molecules can happened for direct fluorination of the molecule or with a prosthetic group. In the last decades Huisgen 1,3-cycloaddition have been widely adopted in radiochemistry because of its high specificity, simple work-up and rapidity.