| 摘要 |
A method of imaging a tumor by magnetic resonance imaging (MRI) of liver and/or spleen is provided which employes microspheres composed of a biodegradeable matrix material with a particulate superparamagnetic contrast agent therein. The microspheres have diameters of less than 1.5 microns, and the ferromagnetic contrast agent, such as magnetite, has a particle size below 300 Angstroms. The superparamagnetic microspheres when administered intravenously segregate through the reticuloendothelial system in the liver and spleen where they reduce the T2 relaxation time to obtain improved MR imaging. In the T2 or mixed T1 and T2 images obtained by the MRI examination, the normal liver and spleen tissues appear dark and the tumor appears light with distinct margins therebetween.
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