FOLH1 and neoplasm: Since tracer internalization is a key factor for the efficiency of tumor uptake and retention, the higher internalization of EuE-k-18F-FBOA and EuE-k-β-a-18F-FPyl and the enhanced PSMA-targeting characteristics compared to 18F-DCFPyl and 18F-PSMA-1007 correlates with the approximately 50% enhanced tumor accumulation in micro PET imaging and biodistribution studies (12.7 ± 2.0% IA/g, 13.0 ± 1.0% IA/g, 1 h p.i. vs 7.3 ± 1.0% IA/g (18F-DCFPyl), 7.1 ± 1.5% IA/g (18F-PSMA-1007), 1 h p.i.)in LNCaP-tumor-xenografts (Figs. 3 and 4).