Abstract: This invention relates to materials exhibiting certain magnetic and biological properties which make them uniquely suitable for use as magnetic resonance imaging (MRI) agents to enhance MR images of animal organs and tissues. More particularly, the invention relates to the in vivo use of biologically degradable and metabolizable superparamagnetic metal oxides as MR contrast agents. Depending on their preparation, these metal oxides are in the form of superparamagnetic particle dispersoids or superparamagnetic fluids where the suspending medium is a physiologically-acceptable carrier, and may be uncoated or surrounded by a polymeric coating to which biological molecules can be attached. These materials are administered to animals, including humans, by a variety of routes and the metal oxides therein collect in specific target organs to be imaged; in the case of coated particles, the biological molecules can be chosen to target specific organs or tissues.

Abstract: This invention relates to materials exhibiting certain magnetic and biological properties which make them uniquely suitable for use as magnetic resonance imaging (MRI) agents to enhance MR images of animal organs and tissues. More particularly, the invention relates to the in vivo use of biologically degradable and metabolizable superparamagnetic metal oxides as MR contrast agents. Depending on their preparation, these metal oxides are in the form of superparamagnetic particle dispersoids or superparamagnetic fluids where the suspending medium is a physiologically-acceptable carrier, and may be uncoated or surrounded by a polymeric coating to which biological molecules can be attached. These materials are administered to animals, including humans, by a variety of routes and the metal oxides therein collect in specific target organs to be imaged; in the case of coated particles, the biological molecules can be chosen to target specific organs or tissues.

Abstract: This invention relates to an improved method for obtaining the in vivo MNR image of an organ or tissue of an animal or human subject. More specifically, this invention relates to the use of small (about 10 to about 5,000 angstroms in diameter) biodegradable superparamagnetic metal oxide particles for use as imaging agents. The particles, which may be uncoated or surrounded by a stable polymeric coating, can be mixed with a physiologically acceptable medium to form a uniform dispersoid which can be administered to the subject by a variety of routes. Once administered, the particles collect in the target organ or tissue where they will remain for a time sufficiently long for an image to be obtained, but are ultimately metabolized or cleared within about 7 days.