A functional gadolinium contrast agent comprising a gadolinium cation and a ligand secured to the gadolinium cation is disclosed, the ligand comprising a reactive group capable of bonding to a capture substrate. A method of removing gadolinium contrast agents from a patient is disclosed, the method comprising providing a gadolinium contrast agent containing a reactive group; providing a capture substrate for insertion into a patient's bloodstream; administering the gadolinium contrast agent to the patient; conducting a magnetic resonance imaging procedure; and sequestering the gadolinium contrast agent on the capture substrate. A system for removing gadolinium contrast agents is also disclosed.