I don't remember if the test I had in 1983 was the same but it did involve injection of isotopes and a couple hours worth of photos being taken. In my case they weren't finding anything to cause my incredible pain. There were no stones or apparent causes. After the test was done they saw something that gave them reason to go ahead and remove the gall bladder. They still weren't exactly sure what it was, but it was done. When I went in for my post op exam with the surgeon who originally didn't want to do any surgery (my mom had her gall bladder out at a relatively young age and I was only in my early 20's) I asked him, "so, did it need to come out after all?" He said there was a cholesterol build up on the OUTSIDE of the gall bladder and it would have never shown on an xray. It was an odd thing. The only thing I can think of that might have done it, if there was any chance of the damage being from an INJURY to the gall bladder, my ex had punched me in the stomach a few months earlier (didn't report it right away and wasn't seen in hospital) and I had a bruise on that part of my stomach.
Anyways, at least these days they can remove the gall bladder laparoscopically. I have an incision scar that is close to a foot long or more where they had to open my abdomen. Even if I finish losing my weight, I'll never wear a 2 piece bathing suit due to this hideous thing. Recovery time is MUCH quicker with the newer surgery. I was in the hospital for several days and had a recovery of 6-8 weeks or so.
Good luck