<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A region of interest in an image chosen for comparison purposes because its uptake properties have some desired feature.</n0:def-definition><n0:def-source>NCI</n0:def-source><n0:attr>Dr. Joseph A. Thie</n0:attr></n0:ComplexDefinition>