We developed a nanosized perfluorocarbon-based system with incorporated paramagnetic Gd(III) chelates, able to generate a quantitative ¹⁹F MRI signal, while in parallel capable of modulating the ¹H MRI signal in response to the coordination of Ca²⁺ ions. Subsequently, we performed experiments in vivo and estimated the concentration of the applied probe in the tissue by means of ¹⁹F MRI.