Na, this is all well-known work. This field is seriously big, lots of publications on it dating back to the early '90s.

This is a regulated industry. If you don't jump through the necessary hoops, the US government will shut you down and there are many laws on the books they can use for this. There are many laws beyond HIPAA (which exists to make it easier to share data, not harder) which apply.

OP is probably talking about the legality of American hospitals using this software in an official capacity like some Chinese hospitals seem to be doing.

I'm completely unfamiliar, but it wouldn't surprise me if for diagnosing? software like this to be used in an official medical capacity in America it would need to go through some sort of particular vetting process because if it isn't it might leave hospitals who use it open to lawsuits.