Nuclear Medicine and Biology is intended for original research contributions describing original synthesis, in vitro tissue studies, or in vivo use of radiotracers, radiopharmaceuticals, or therapeutic agents. Papers concentrate on the synthesis, testing in vitro, and examination of a compound in vivo. Extensive studies proving the mechanism of localization in vivo whether the radioactive substance is based on receptor-, enzyme-, or tumor antigen-binding or other well defined processes are an integral part of each evaluation. Additionally, studies should define a significant compound that is a sensitive probe of a biochemical change in vivo.