Online OsiriX Documentation/Opening Mac-Unfriendly CDs with OsiriX
If your culprit CD does not show up with the Finder. You may try to open the CD using Import... within OsiriX. On my ibook G4 the data were easily imported from the CD written on a Siemens CT-workstation running Windows.
Some CDs (eg Agfa Impax) are burnt with the session unfinalised. These discs can not be read by Macs. One solution is to mount these CDs on a Windows or Linux box and share them across the network.