Haven't had one, but as I understand from a Nuc. Med. friend I just IM'd, (gotta love Dan, he's always on the net ) it should take about 2 hours (+/-) depending on the speed/function of your gallbladder. They put an IV in your arm and inject what they call a tracer drug. This is a drug that has an affinity to the specific anatomy they are checking, i.e. some are attracted to lungs, others to liver... It's actually a radioactive isotope that they can pick up on their machine. VERY short 1/2 life so, long term, it's relatively harmless. The NM beds aren't too bad. I've played patient to the students (w/o injection) and almost fell asleep one time.

Good luck and I hope you get good news.

cindy