Advances in the Development of Multimodal Imaging Agents for Nuclear/Near-infrared Fluorescence Imaging

Multimodal imaging agents were first introduced a decade ago and consist of a targeting moiety that is dual-labeled with radioactive and fluorescent contrast. These compounds allow whole-body and intraoperative imaging to be performed through administration of a single agent and provide complementary diagnostic information that can be used to guide tumor resection. Since their initial evaluation, interest in dual-labeled agents has continued to grow and their design has subsequently evolved alongside the development of novel chelating agents, improved fluorophores, and highly selective coupling techniques for bioconjugate formation. In this review, will discuss how changes in the labeling components and schemes for multimodal agent development have impacted imaging performance and will focus on antibody- and peptide-based agents as models for dual labeling. We will also describe the growing role of modular dual labeling strategies as well as direct labeling methods using radiohalogens.