One of the many advantages of titanium jewelry, on top of its biocompatibility, is that it is completely nonmagnetic. This means it's completely safe for MRI scans, X-rays, CT scans, PET scans, etc. The only time it could be an issue is when the jewelry could block the view during the scan, say nipple piercings in a lung X-ray. If your doctor still insists your jewelry needs to come out, we often have safe glass retainers to wear during the scan. This is especially important if your piercing is still new or freshly healed.
You can read about it (and pass it on to your doctor) in these articles: