Source:http://linkedlifedata.com/resource/umls/id/C1522485
NCI: A substance (such as a radioisotope) used in imaging procedures.,NCI: A substance that is identifiable by virtue of its radioactive signature, color, or other distinguishing physical property, such as a dye, radioactive isotope, or inert chemical, that is introduced into a biological or mechanical system and can be followed through the course of a process, providing information on the pattern of events in the process or on the redistribution of the parts, elements, or events involved.