Labeling with radiometals or Al18F2+

Radiometalation by gallium-68, copper-64 or zirconium-89 in chelating complexes attached to peptides or proteins make use of high specificity and selectivity of those compounds with the outstanding advantage of application in therapy just by taking a different radionuclide appropriate for therapy such as yttrium- 90 or Lutetium-177.

A recent very important alternative is the labeling with Al18F2+. The surprising feature is the fact that this compound was found to exhibit the property of a radiometal. Therefore, the advantages of fluorine-18 longer half-life (110 min) instead of 68 min in case of gallium, lower positron energy (0.65 MeV vs. 1.9 MeV (68Ga)) resulting in best imaging quality are combined with those of complex formation which keeps the alternative application for therapeutic use by using a different radionuclide.

Availability of fluorine became great since the number of cyclotrons increased to a kind of “all around” availability. Just by flushing the target system after a big production run a high amount of 18F activity is obtained as “waste” so that practically no costs exists. That is particularly important since the price of a 68Ge/68Ga generator has continuously been increasing, there are reports about an increase of a factor of five since the beginning.  For one or two patients a 68Ga labeling whereas with fluorine-18 a single daily batch is prepared for a couple of patients.