NSF Award
1303031
1133908<br/>Yu<br/><br/>This project aims at engineering fluorinated paramagnetic complexes (FPCs) as imaging agents for multi-chromic 19F magnetic resonance imaging (MRI). It has three objectives: i. Fabrication of FPCs; ii. In vitro testing of FPCs; iii. In vivo testing of FPCs. Each FPC is a molecular complex formed between a fluorinated symmetric dendrimer chelator and paramagnetic metal ions. One fluorinated chelator can be paired with different paramagnetic ions to generate 19F signals of different resonant frequencies. Thus, only one synthesis is needed for the fabrication of a set of FPCs. Four FPCs, each with a characteristic 19F resonant radiofrequency, will be made. Technical specifications on the performance of FPCs in terms of signal frequency and relaxation times, solubility, serum stability and in vivo elimination half-life are proposed. In vitro and in vivo testing will be conducted to evaluate whether the FPCs meet the performance specifications. In vivo testing will be conducted in mice using a 3T clinical MRI scanner. Fabrication and testing will be conducted iteratively. In addition to FPC development by the PI's group, 19F MRI techniques will be developed by the co-PI's group. Such techniques allow the collection of 19F/1H dual images at multiple 19F frequencies and can rapidly determine 19F relaxation times in vivo. The novel concept proposed in this project is to construct a symmetric intra-molecular paramagnetic shield around the MRI signal emitter. The paramagnetic shield has two functions: to modulate the MRI signal to generate multi-chromicity ("color"), and to insulate the MRI signal from the fluctuations of surrounding magnetic field. The generation and stabilization of resonant frequencies are critical issues in the engineering of imaging agents for multi-chromic MRI.
