ABSTRACT
The expansion of fused imaging instrumentation, including positron emission tomography (PET)/computed tomography (CT), single-photon emission CT/CT, and, more recently, PET/magnetic resonance (MR), has stimulated research and development of novel molecular probes that can provide targeted imaging for multiple modalities. Synthesis of multimodality imaging probes began with the combination of molecular imaging contrast agents with fluorescence molecules. As the field has progressed, there has been a greater interest in merging other imaging functionalities including fluorescence, CT- and MR-contrast agents, and radioisotopes to take advantage of the fused instrumentation. Encapsulation strategies to deliver multiple probe payloads to target cells have been explored using liposomal delivery vehicles, micelles, and other macromolecular carriers. Alternatively, advances in nanotechnology have aided the combination of metal chelators into nanoparticle designs, enabling simultaneous detection by multiple modalities. The development of novel synthesis strategies has facilitated the fusion of different functional moieties into a single compound, with the aim of complementary concurrent measurements from a single probe using fused instrumentation. There remain significant challenges in probe development, particularly relating to the differential requirements for various imaging modalities with regard to concentration and delivery, but new advances in chemical synthesis continue to generate interesting and applicable tracers. As development of these multimodality probes becomes more mainstream and widespread, new applications in clinical and preclinical settings begin to emerge. In this chapter, we will discuss the chemical development and evaluation of novel multimodal imaging probes under the broad designations of encapsulation, nanoparticles, and other molecular probes. We will then focus on the emerging clinical and preclinical applications of these targeted probes in cardiovascular medicine.
