New Radiopharmaceutical Tools in Imaging

The strength of Nuclear Medicine imaging are the compounds to be used as radioactive probes. Unfortunately there are many constraints both in relation to physiological parameters such as metabolism as well to compound related properties like lipophilicity or chemical stability. Due these constraints, many, otherwise promising, compounds could not be used in Nuclear Medicine imaging. Within this review a brief summary is given regarding possible limitations for imaging probes and approaches or techniques to overcome the constraints. Even so the review focuses on imaging with central active compounds, many of these problems appear likewise when targeting peripheral organs. Besides the established approaches to overcome limitations some new, so far not explored, directions are discussed. Finally, a potential new tool in imaging will be presented, a trojan horse approach for transportation of radioligands. Here, like in conventional drug development, lipid nanoparticles may have potential to be used as carrier systems in Nuclear Medicine as well. This, so far not explored, concept is briefly presented.