Nancy Kemeny, MD: A virtual colonoscopy is doing a colonoscopy with an x-ray machine. Instead of a physician, a gastroenterologist using an instrument to go up into a colon,there's no instrument involved, you're having an x-ray.However, that's the good news. However the prep is the same, which is I think the hard part of the colonoscopy, you're doing the same clean out,you have to take the same amount of enemas and everything else. The other thing is that when they actually do it, you have to hold, they have to push like air into you,and you have so hold it, so it's not like a very comfortable procedure. Some people say it's quite uncomfortable.Plus, if there's something there, if they find a polyp, they can't remove it, which means you then have to have a colonoscopy.I think the place possibly to use it if you have a very old patient, and you don't want to put them through a colonoscopy and you want to do some sort of screening,and if it turns out to be negative, fine, you didn't, you don't need a colonoscopy, but I'm not sure exactly where we're going to use thisbecause it has the disadvantage that if there is a problem, you still have to have the colonoscopy.