Sci‐Fri PM Imaging‐12: Multimodal Contrast Agent for Combined CT and MR Imaging

Interest in the area of multimodality imaging has also been prompted by the realization that such techniques offer much more sophisticated characterization of the morphology and physiology of tissues and organs, and that confidence gained in the accurate correspondence or registration of different modalities greatly enhances their value. This study is aimed to provide a contrast agent based approach to combine information obtained in CT and MR. Specifically, a liposome‐based dual modality contrast agent co‐encapsulating iohexol, an iodine‐based CT contrast agent, and gadoteridol, a gadolinium‐based MR contrast agent, was developed and characterized. Previously, our group characterized the in vitro physico‐chemical properties of this liposome‐based contrast agent. In this study, CT and MR‐based assessments of the in vivo stability of the liposome‐based contrast agent was conducted in a rabbit model. Visual contrast enhancement and measurable signal increases produced by the presence of the contrast agent carrying liposomes was induced in various organ systems (i.e. heart and blood vessels, liver, spleen, kidney and intestines) in both imaging systems over a 7‐day period. The blood circulation half‐life of the present liposome formulation in rabbits was found to be 45.4 ± 2.5 hours. The simultaneous signal enhancement seen in both CT and MR, and the long circulation life of this liposome‐based contrast agent makes it attractive for use in applications such as longitudinal blood pool imaging, feature‐based CT and MR image registration, and imaging‐based tracking of liposomal therapeutics.