It's an interesting question Eccles, I'd be interested to know why too. It really does feel as if you're wetting yourself doesn't it, and you're warned by the scan person that it'll happen. Must be some physiological explanation but I can't find one.
Who frowns on random links mamy? I didn't know that.
I'd seen the thing about mucous membranes but it doesn't explain why really, nice of you to try though :)
I think it is the agent that is fed into you just prior to the scan running. The dye is designed to be readily receptive to the x rays generated by the machine and therefor "blocks" them compared to the tissue areas that do not contain the dye. The Xrays are very high energy indeed, and the dye is slightly warmed by the rays as they block them(excited molecules). Hence that warm feeling in the areas where the dye readily gathers. Throat and groin. I have had about a dozen ct scans and trying to get the reason out of the technicians is like drawing hen's teeth.