In vitro demonstration using 19F magnetic resonance to augment molecular imaging with paramagnetic perfluorocarbon nanoparticles at 1.5 Tesla

Objectives: This study explored the use of F-19 spectroscopy and imaging with targeted perfluorocarbon nanoparticles for the simultaneous identification of multiple biosignatures at 1.5 T. Materials and Methods: Two nanoparticle emulsions with perfluoro-15-crown-5-ether (CE) or perfluorooctylbromide (PFOB) cores were targeted in vitro to fibrin clot phantoms (n = 12) in 4 progressive ratios using biotin avidin interactions. The CE nanoparticles incorporated gadolinium. Fluorine images were acquired using steady-state gradient-echo techniques; spectra using volume-selective and nonselective sampling. Results: On conventional T1-weighted imaging, clots with CE nanoparticles enhanced as expected, with intensity decreasing monotonically with CE concentration. All clots were visualized using wide bandwidth fluorine imaging, while restricted bandwidth excitation permitted independent imaging of CE or PFOB nanoparticles. Furthermore, F-19 imaging and spectroscopy allowed visual and quantitative confirmation of relative perfluorocarbon nanoparticle distributions. Conclusions: F-19 MRI/S molecular imaging of perfluorocarbon nanoparticles in vitro suggests that noninvasive phenotypic characterization of pathologic biosignatures is feasible at clinical field strengths.