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Comment by vmg12 | Hacker News Reader

> "Incidentalomas" or unexpected, probably benign, findings are annoying to physicians

For a lot of these things I wonder why they don't just do multiple scans just to see how things develop. Is it a cost issue?

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That's generally exactly what we do, which if we need to follow 2x or 10x incidental lesions in the population, leads to cost and availability problems. A lymphoma patient in remission needs follow up scans too, and I don't want them to have to wait 3 months because thousands of people are now following up their benign adrenal adenomas.

If you could dramatically reduce cost and improve availability, would this still be a problem?

What's the limiting factor that prevents medical imaging from getting cheaper and more available?

Excluding the cost of X-ray/CT/MRI machines, operating them, getting people to them and through them, sometimes injecting contrast, and sometimes dealing with side effects of said contrast, radiologists, I think. You can scale all of the above except interpretation. AI is the natural next thought for how to scale that part, but it's been thought that this would happen any moment for over a decade.

The machines are expensive (millions range per MRI scanner), staffing the machines nearly around the clock with highly educated technologists, repair/maintenance of expensive specialized machinery, radiologists to read each scan (esp with a current shortage), means it’s very expensive to set up and run an imaging center. Opening and owning an imaging center used to be seen as fairly lucrative. and many radiology private practices did just that, however, the economics have changed over the years with dropping reimbursements, staffing shortages, etc and now often these imaging centers are seen as a liability rather than an asset.

I feel like the first part of this explanation reminds me of stories about mainframe computers in the 1950-70s - highly expensive special gear that needs special operators. Is there something about the physics of the process standing in the way?

This is definitely a part of standard follow up for small findings and part of the guidance for incidentally detected lung nodules smaller than <8mm.

I think mammography is a great example. Many people are quite surprised to hear that the Positive Predictive Value of a screening mammography is only in 10-15% range. This despite mammography being a pretty sensitive test. This is because despite good test performance characteristics, applied across a large population of relatively health people, the 2-5% false positive rate is a large number of people.

Statistically overdetection leads to poorer outcomes because interventions have a risk as well. That's why everyone doesn't get a yearly full body CT scan, for example. The current guidelines are based on optimizing for maximum good, and believe it or not some things are best not known about because the risk of dying from it is about the same as the risk of the treatment.

Because people discovering "Incidentalomas" will be too freaked out to wait "just to see how things develop".

Cost, time, and for things like CT's, trying to limit your radiation exposure

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