pH sensitive MRI contrast agents
AssigneeBoard of Regents, The University of Texas System
InventorsA. Dean Sherry, Shanrong Zhang, Kuangcong Wu
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Abstract
A composition and method is disclosed for providing a magnetic resonance imaging contrast agent that is sensitive to pH, the compound and salts thereof including, a tetraaza base having a spacer at each of the amide groups, and a proton exchange attached to each of the spacer molecules, wherein the proton exchange group groups mediate proton exchange with water molecules that are trapped within the tetraaza base molecule.
Claims20
A chelating compound for use in magnetic resonance imaging, or a salt thereof, comprising:
- a tetraaza base having the formula:
- wherein pendent arms R, R′, R″ and R′″ each include an acetamide spacer group, at least two of said acetamide spacer groups which terminate with proton exchange groups containing at least one hydrogen atom that is configured to hydrogen bond to an inner-sphere water molecule associated with a trivalent lanthanide ion coordinated to amide oxygens of said acetamide spacer groups and to nitrogen atoms of said tetraaza base such that said inner-sphere water molecule has a average lifetime of greater than 1000 ns.
A magnetic resonance imaging contrast agent, or a salt thereof, comprising:
- a tetraaza base having the formula:
- wherein pendent arms R, R′, R″ and R′″ each include an acetamide spacer group at least two of said acetamide spacer groups which terminate with proton exchange groups containing at least one hydrogen atom;
- a gadolinium ion that is coordinated to amide oxygens of said acetamide spacer groups and to nitrogen atoms of said tetraaza base;
- and
- an inner sphere water molecule that is hydrogen bonded to said proton exchange groups and said inner-sphere water molecule having an average lifetime that varies with a pH of an aqueous solution containing said contrast agent.
A method of using a contrast agent to obtain magnetic resonance images of a patient comprising:
- administering to a patient a magnetic resonance imaging contrast agent, or a salt thereof, comprising:
- a tetraaza base having the formula:
- wherein pendent arms R, R′, R″ and R′″ each include an acetamide spacer group at least two of said acetamide spacer groups which terminate with proton exchange groups containing at least one hydrogen atom;
- a gadolinium ion that is coordinated to amide oxygens of said acetamide spacer groups and to nitrogen atoms of said tetraaza base;
- and
- an inner sphere water molecule that is hydrogen bonded to said proton exchange groups and said inner-sphere water molecule having an average lifetime that varies with a pH of an aqueous solution containing said contrast agent;
- and
- taking a magnetic resonance image of the patient.
Dependencies are inferred from the claim text.