[Sethomas]

Well, the way you describe it, it doesn't sound like an ultrasound at all. Ultrasounds are just that--they operate on detecting response patterns from induced reverberations. Unless the physics to ultrasound has gone waaaaaay more advanced than I thought possible, then I doubt that's what it was. For one thing, ultrasound scans are done in such a way that allows you to watch real-time movement (very superfluous for detecting a chemical anomaly in an organ of any type) and for another thing, I don't think that it's plausible that acoustic analysis could be made on ultrasounds without a wand-like device touching your body.

So, I would guess that it was either an MRI or a PET scan. If it were an MRI, the IV injection would have been a contrast solution that your gallbladder would be adept to pick up and would make their desired image either more or less sensitive to the magnetic field. If it were a PET scan, the injection would have been a metabolic compound that contains an isotope with a very short half-life so that your gallbladder would start emitting anti-matter and the scan detectors could produce an image from the resulting gamma rays that shoot out of you.

When I learned about how PET scans work, I got the impression that medical imaging physicists have a pretty base disregard for human life but have a morbid curiosity of how they can figure out what is going wrong with the human body. I'm just waiting for the statistically inevitable day when a doctor says, "well, you didn't have cancer BEFORE the scan..."

It's MY BODY, it's MY CHOICE. I don't want positrons in MY BODY reacting with MY valence electrons.