If you Google "full-body MRI" you'll find lots of vendors.

https://desertmedicalimaging.com/blog/whole-body-screening-m...

https://www.humanlongevity.com/whole-body-mri/

Buyer beware, though. Scary false positives abound and may lead to anxiety and unnecessary, invasive procedures.

The problem is, the scans (neither MRI nor CT) are specific enough to rule out danger of some stuff you find. So the next thing is you'll need to start taking some nice needle biopsies, being worried about them.. some things you can't do with the needle biopsy and you need to actually get in there.

A subset of these things you find you'll get the answer that they're tumors but harmless and let's leave them, and then you'll go worry about them for the next 10 years..

Doing medical tests without reason is a russian roulette with your psyche :)

I agree in principle though that it would probably be good to have an early "baseline" full body scan and then get incremental checks every year.