Best let the doc...
...Decide. They know what they are looking for and how best to look for it.
You shouldn't tell your plumber how to fix the leaky faucet (other than to do quality work), so i wouldn't try to micro-manage your doctor. First decide if you want to have the test (after hearing the risks, benefits, and alternatives), then let the doctor decide how to do it. Don't tie his/her hands.