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by bonsai_spool 239 days ago
> I do not buy this argument. The error would be in misinterpreting the image and taking the unnecessary treatment, not in doing the test in the first place. How is there any benefit in having less information?

There is no 'perfect information' but instead there is noise with every signal. It feels like that shouldn't be true ('the picture shows exactly what is happening, right?') but there are several levels at which the 'truth' that is assessed in an MRI can be degraded that have nothing to do with misinterpretation.

Even 'misinterpretation' is tricky - if something is only sometimes going to cause a clinically bad outcome, commenting or not commenting isn't a question of interpretation but of personal practice standards.
1 comments
nojs 239 days ago
It’s definitely an imperfect signal, but we are capable of making decisions under conditions of noise and uncertainty. In other fields we would quantify the uncertainty, the consequences of making the error in either direction, and then act accordingly.

As a thought experiment, if MRI was as cheap and fast as testing blood pressure, do you think they’d still be given as rarely?

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bonsai_spool 239 days ago
I think if we had a perfect tool where you can get MRI (and CT) data in the time it takes to get a blood pressure reading, it would only be used to detect slam-dunk diagnoses for further screening which is how we use blood pressure.

You’re assuming that we would skip this step, implicitly.

Now when would we do further screening? In a Bayesian framework, when we have a certain pre-test probability that we think we can improve to our desired level of post-test probability in order to take an action.

The fact that this is all automated doesn’t change our uncertainty about whether borderline calls should be targeted. Indeed, we’ll likely have more stringent criteria about things to ignore than are used today, and that may be worse for the small number of times we currently catch an actionable incidental finding.

And we’re not even beginning to consider cost, resource misuse, and the risks we’re incurring (an MRI machine isn’t safe to be around and costs a lot to maintain)

Edit: the things that kill people are smoking, heart disease, lack of exercise and poor diet. Targeting these is so much more useful than detecting a larger number of incidental findings

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