The present invention relates to novel, radiolabeled mGluR2/3 ligands, selective versus other mGlu receptors which are useful for imaging and quantifying the metabotropic glutamate receptor mGlu2 and 3 in tissues, using positron-emission tomography (PET). The invention is also directed to compositions comprising such compounds, to processes for preparing such compounds and compositions, to the use of such compounds and compositions for imaging a tissue, cells or a mammal, in vitro or in vivo and to precursors of said compounds.
