US Patent 4,656,026
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
An improved imaging technique involving nuclear magnetic resonance. Known drug or neurotransmitter receptor ligands are covalently bound to magnetic resonance image enhancing spin label compounds, such as sterically hindered free radical nitroxide compounds, with the resulting adduct being administered to a patient, and thereafter when the ligand is bound to specific receptor sites in the soft tissue such as the brain, regional tissue area is assessed with nuclear magnetic resonance, allowing diagnostic discrimination.
Coffman, Jeffrey A. and Barfknecht, Charles F. Magnetic resonance (MR) image enhancement compounds for specific areas of the brain. US Patent 4,656,026 filed December 10, 1984 and issued April 07, 1987. https://ir.uiowa.edu/patents/52