Peter, thanks for the quick response! I am still getting acquainted with imagery data and metadata. The ArcGIS Auxillary Files resource indicates that these files include many types of information but doesn't mention the Item Description metadata:
I've attempted to generate the aux.xml file but all it includes is other metadata information (statistics, coordinate system, etc.), not the information I intend to carry over. Also, the original item description metadata (image clarification above) in FGDC format would ideally be downloaded by the user from the web-based GIS.
It seems that there are ways to add the item description metadata to the aux.xml via GDAL RAM, but the item description metadata in FGDC format will not be maintained. The images are in various formats and GDAL RAM only seems to support GeoTIFFs. Does it support other image formats too (for example .img)?