Which cat diagnostic imaging tool is the most accurate?

There again, it depends on what you're looking for. I hate to be vague, but it's true. That's a tough one to answer with just a black and white answer. They're all pretty good in their own right. You have a broken bone, don't ultrasound it. Start with an X-ray. And if you need more detail, then a CT scan would probably be next. Again, you also have to keep in mind in the real world, a CT scan is not available at your neighborhood veterinary clinic. So usually CT scans and MRIs are reserved for cases where you can't get an answer with ultrasound, X-rays, blood work, and you've exhausted all other diagnostic abilities. In those cases, you may have to refer that cat to a teaching hospital or a referral center or something like that, where they have specialists. And they are the ones that would typically have some of those advanced modalities. So it's hard to say which one is more accurate just as black and white as that question implies.