When one considers the purpose that the titanium chip serves... that is to say, identifying where a biopsy was performed for future diagnostic referencing... the value in having it far out-weighs the reasons to not have it. Now, if you happen to be allergic to titanium... then, that would give a valid cause for concern.
It's a very common practice and the titanium chip is so small that it is inserted thru a needle. It's valuable as a marker for future reference to indicate where the biopsy was done and also so the area would not be confused with a new finding later. I have several pieces of titanium in my spine and never give it a second thought .... you won't set off alarms either. Regards ....