"If you could make it work couldn't you just patent it and/or sell [it]?"
In a word - no. I've seen a few cycles of medial product development, funding, etc, and functionality isn't the primary goal. Sure, the stuff has to work, and incremental improvements are good, but preventative diagnosis? That's just bad business.
Try getting funding for something that lets you detect heart attacks via a breath sample rather than a lengthy blood test - if you have the former, you don't need to perform surgery just in case, do you? Would you pay more money to allow your customer to buy less of your product? There's just no business case.
The best motivator for getting super tech into hospitals is that hospital A will be vilified for not having some tech if hospital B -does- have it. But that's a chicken-and-egg scenario, with everyone starting out with the incentive to not begin the cycle.
If you gave me the *choice between* the chance of making a hundred million selling the device / device company to hospitals / investors, and the certainty of $10m, I'd take the $10m in a heartbeat.
As an example, in the 1970s, my father developed a neural stimulation feedback device whose aim was to help patients with spinal injuries recover some muscle control. (This is to the best of my memory; I might be wrong on some details.)
He got the opportunity to trial his device at a hospital, with a patient who hadn't felt his legs for six months. The trial was a significant success - not jump-up-and-walk, but the patient actually regained some feel and a little toe motion. A big deal, particularly back then. But the executives were unaccountably sour.
In the end, the hospital said they weren't interested in doing any more work on the project, and he should get his prototype. Apparently, the patient was cried, and begged for it to not be taken away.
My dad saw similar situations play themselves out in other medical product development and consulting roles. Obviously some better and some... well, not many worse. But it's not good, and I'm definitely not going to be angling for the medical instruments business.
Biting the hand that feeds IT
