While I'd issue a strong caution about anything collected from download dot com, a program called OsiriX is available from there that claims to offer what you want. It's a trial version, however, so is probably very limited and could be irritating. You can always use google as your friend for this or maybe you have a friend with a PC. These disks provided by your radiologist will often have a viewer right on the CD/DVD so look for that as well.
I have had several MRI's taken in the past years. The radiographers have given me discs, but my Mac does not seem to have the App to open UDF discs. How can I open it to see the actual X'ray,
Sorcha

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic