A Bard port, also known as a mediport, is surgically connected to a large vein or artery and implanted under the skin, for direct access to the blood stream. Usually, if there is an issue getting an intravenous started on someone (due to collapsed veins) that needs routine and long-term IV medication therapy (chemo, etc.), they will have one of these implanted for easy access.
You can find more information at this site: http://www.bardaccess.com/port-mri-hard.php