Methods for circumventing the problem of free radial reduction associated with the use of stable nitroxide free radicals as contrast agents for magnetic reasonance imaging
AssigneeThe State of Oregon Acting by and through the State Board of Higher Education on Behalf of the University of Oregon
InventorJohn F. W. Keana
Life of this patent
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Abstract
Nitroxide contrast agents for MRI have a long useful life and can be administered in low concentration doses. Such agents include nitroxide-doped liposomes that encapsulate an oxidant and large molecules having surfaces covered with persistent nitroxide free radicals.
Claims44
In an MRI contrast agent which is a liposome having a bound spin label that is subject to reduction, and thus loss of contrast enhancement capability when in a reducing environment, the improvement wherein the liposome incorporates oxidizing means for oxidizing and thereby restoring spin labels that have been reduced.
An MRI contrast agent, the agent comprising:
- a liposome having a bilayer shaped to define a compartment;
- multiple nitroxides incorporated into the bilayer;
- and
- an oxidant substance inside the compartment.
An MRI contrast agent comprising a molecule or assembly of molecules, the molecule or assembly having at least ten nitroxide groups positioned to contact surrounding bulk water and effect magnetic relaxation.
A method for enhancing the magnetic resonance image of a target tissue, the method comprising providing, in a target tissue, an MRI contrast agent comprising a molecule or assembly of molecules, the molecule or assembly having at least ten nitroxide groups positioned to contact surrounding bulk water and effect magnetic relaxtion, the agent being provided in an amount sufficient to enhance the magnetic resonance image of the target tissue.
A salt of the cation:
- ##STR30## wherein R is an alkyl or aromatic group with or without hetero atoms present and with or without a nitroxide.
An arborol of the formula:
- ##STR32## wherein R is an acyl nitroxide, phosphoryl nitroxide or aromatic nitroxide.
Dependencies are inferred from the claim text.