Mine was done 3 or 4 years ago. Was normal, so that's that. Never had a ct scan since, because (they told me): if the thymus is normal when you already have your diagnosis, it stays normal.
I do not know if this is indeed true, but I never had a scan since, and never seen a surgeon, never an operation. I asked about it a year ago, they told me once again: it was normal years ago.

What a coincidence, mine was ordered by the pulm too! It's like sb says, it doesn't matter, as long as a good radiologist takes a good look at it. I think most of the time, your neurologist will take a look at it too (mine did, so did my pulm).