**Preface to "Radiopharmaceuticals for PET Imaging—Issue A"**

Positron emission tomography (PET) has become a clinical routine in public healthcare. To perform diagnosis with PET, suitable radiopharmaceuticals are needed. A variety of drug targets are present in different diseases. Even in the same disease (e.g., breast cancer), the profile of drug targets may vary greatly among patients. Therefore, new radiopharmaceuticals are needed as ever before to read out the target profile in different ways. This Special Issue "Radiopharmaceuticals for PET Imaging" is dedicated to presenting the fresh research results on radiopharmaceuticals. We are pleased to see that many research labs have been able to disseminate their results, and 12 papers are included in this edition, Issue A; Issue B on the same topic is currently under editing. We hope this issue will contribute to promoting scientific communication among its readers. We hope you enjoy reading.

> **Anne Roivainen, Xiang-Guo Li** *Editors*
