Heh, I just now did what you should've done and googled HIDA Scan where I found this:
"If you’re having problems with your gallbladder, your doctor may want you to have a special test called a hepatobiliary iminodiacetic acid (HIDA) scan.
During the procedure, a technician injects a tiny amount of a radioactive compound into your bloodstream. As it travels through your liver, gallbladder, and small intestine, a camera tracks its movement and takes pictures of those organs.
A HIDA scan shows how well your gallbladder is working. It can also check your liver function, since these two organs work closely together."
https://www.webmd.com/digestive-disorders/gallstones
Click the link, read it, there's much more.
I had HIDA about 6 years ago, if I recall u eat a cheeseburger and they do the scan. They found my bile duct transfer or whatever it's called was at about 17%. Didn't seem to bother me at the time. I have thus far forestalled surgery since then, for which I credit drinking half of a small lemon in soda water (soda just taste preference, not required) daily. But this week the ol' GB pain came back, and I again quit eating fat. Pain is improving, but I'm afraid I'll have to do surgery. Keep your fingers crossed for me.