I had one a couple of years ago. You have to strip off down to the waist, then you have some kind of gel applied to various parts. Then electrodes are stuck on here and there, you lie down on a kind of bed, and the technician switches on the machine, which has a screen. The technician can read all about what's going on inside your upper half. It's not unpleasant or painful. When it's finished, you are given a roll of tissue paper to wipe all the gel off, and that's it.