Good that you've got this set up. The surgical clip thing - wild. This (for discovery purposes) should be good news, though (IMO). At least they can see (SEE even) something is not right. If it showed up on an xray - it's some kind of calcification (or a surgical clip!) - no? Anyone?
MRI is much more likely than a CAT but I won't be completely surprised if parasites evade an MRI also. I'm inclined to agree with PZ's assessments. Forego any CAT if offered/ordered. Useless for parasites. Will show as inflamation only.