Diagnostic labs are just for-profit companies. They’re happy to do tests as long as they get paid by somebody. The only practical restrictions are if you want to convince insurance to pay for it. If you’re paying cash, you can get anything from a simple blood test up to a full-body MRI scan [0].

I got a CT angiogram from a cardiologist here who started her own business specifically to do them. (It’s just her, a nurse, and a CT machine, in a trailer in a parking lot!) Insurance doesn’t pay for imaging like this until things have already gone very wrong, and she feels it should be used much earlier for people who have risk factors.

[0] https://prenuvo.com/

CT is radiation. This is a case where too much testing is detrimental, not merely wasteful. You're sucking up 4 years worth of background for that CT angiogram.