<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A dye or other substance that helps show abnormal areas inside the body. It is given by injection into a vein, by enema, or by mouth. Contrast material may be used with x-rays, CT scans, MRI, or other imaging tests.</n0:def-definition><n0:def-source>NCI-GLOSS</n0:def-source></n0:ComplexDefinition><n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Substances administered during diagnostic procedures that allows delineation of internal structures. Contrast agents appear opaque due to the difference in absorption of X-rays or other electromagnetic waves and surrounding tissue.</n0:def-definition><n0:def-source>CDISC</n0:def-source></n0:ComplexDefinition>
<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Substances administered during imaging procedures that allows delineation of internal structures. Contrast agents appear opaque due to the difference in absorption of X-rays or other electromagnetic waves and surrounding tissue.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>
nci:P98
Positive contrast agents have greater absorption and structures appear light. Negative contrast agents have a lesser degree of absorption and structures appear dark.