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Deep learning outperformed dermatologists in melanoma image classification task

ejcancer.com

21–30 of 94 posts

Re: Deep learning outperformed dermatologists in melanoma image classification task

#21
post #17

Maybe a dumb question from a non-medical guy: are medical images considered "stationary" from a stats viewpoint? That is, will medical images of diseases we diagnose in the next 20 years look a lot like the ones from the past 20 years, or is there a danger of over-fitting on an evolving data set? Could either the technology or the biology of the disease evolve? In a prior life I was a quant trader, and financial mark…

My guess is largely no. The diagnosis and actions taken are in isolated environments e.g, a cancer in person B is not impacted by a diagnosis and treatment in patient A. This is not the case in trading where everyone is analyzing and influencing a single messy environment.

Re: Deep learning outperformed dermatologists in melanoma image classification task

#23
post #17

Maybe a dumb question from a non-medical guy: are medical images considered "stationary" from a stats viewpoint? That is, will medical images of diseases we diagnose in the next 20 years look a lot like the ones from the past 20 years, or is there a danger of over-fitting on an evolving data set? Could either the technology or the biology of the disease evolve? In a prior life I was a quant trader, and financial mark…

This isn’t time series data so don’t need to worry about stationarity.

Re: Deep learning outperformed dermatologists in melanoma image classification task

#24

As always, let's see how well it does in live images. This system outperformed dermatologists on its own validation set of 100 images, which I would encourage you to interpret as "heartening preliminary evidence" but not much more. Posting high scores on your validation set is only as informative as your val set is representative of the real world. 70% specificity, 84% sensitivity looks OK on paper (maybe -- as anoth…

Isn’t DeepMind about to release a medical product that will do something very similar to this? Right now I wouldn’t doubt how well these systems can perform as compared to trained specialists that rely on their eyes even for reading test results.

Re: Deep learning outperformed dermatologists in melanoma image classification task

#26
post #17

Maybe a dumb question from a non-medical guy: are medical images considered "stationary" from a stats viewpoint? That is, will medical images of diseases we diagnose in the next 20 years look a lot like the ones from the past 20 years, or is there a danger of over-fitting on an evolving data set? Could either the technology or the biology of the disease evolve? In a prior life I was a quant trader, and financial mark…

Overfitting to people with certain complexions of healthy skin seems like a potentially much bigger problem than evolution of ailments.

Re: Deep learning outperformed dermatologists in melanoma image classification task

#27

I've always thought that diagnostic-oriented specialties would be most at risk (pathology, dermatology, radiology, ophthalmology). As long as you have procedures, you will have a need for an extremely competent clinician that can synthesize all information and coordinate with use of hands or devices.

All the specialties you cite entail various manual procedures.

Other than that yes, robots are not capable of replacing manual work in médicine yet.

Re: Deep learning outperformed dermatologists in melanoma image classification task

#28
I do research in computer vision and this paper is so bad it's beyond words.

* They give the network is huge advantage: they teach it that it should say "no" 80% of the time. The training data is unbalanced (80% no vs 20% yes) as is the test data. Of course it does well! I don't care what they do at training time, but the test data should be balanced or they should correct for this in the analysis.

* They measure the wrong things that reward the network. Because the dataset is imbalanced you can't use an ROC curve, sensitivity, or specificity. You need to use precision and recall and make a PR curve. This is machine learning and stats 101.

* They measure the wrong thing about humans. What a doctor does is they decide how confident they are and then they refer you to a biopsy. They don't eyeball it and go "looks fine" or "it's bad". They should measure how often this leads to a referral, and they'll see totally different results. There's a long history in papers like this of defining a bad task and then saying that humans can't do it.

* They have a biased sample of doctors that is highly skewed toward people with no experience. Look at figure 1. A lot of those doctors have about as much experience to detect melanoma as you do. They just don't do this task.

* "Electronic questionnaire"s are a junk way of gathering data for this task. Doctors are busy. What tells the authors that they're going to be as careful for this task as with a real patient? Real patients also have histories, etc.

I could go on. The number of problems with this paper is just interminable (54% of their images were non-cancer because a bunch of people looked at them. If people are so wrong, why are they trusting these images? I would only trust biopsies).

This isn't coming to a doctor's office anywhere near you. It's just a publicity stunt by clueless people. Please collaborate with some ML folks before publishing work like this! There are so many of us!

Re: Deep learning outperformed dermatologists in melanoma image classification task

#29

As always, let's see how well it does in live images. This system outperformed dermatologists on its own validation set of 100 images, which I would encourage you to interpret as "heartening preliminary evidence" but not much more. Posting high scores on your validation set is only as informative as your val set is representative of the real world. 70% specificity, 84% sensitivity looks OK on paper (maybe -- as anoth…

Isn’t DeepMind about to release a medical product that will do something very similar to this? Right now I wouldn’t doubt how well these systems can perform as compared to trained specialists that rely on their eyes even for reading test results.

The question is whether we really measure things that are relevant and specific to the diagnosis. As of today the answer is largely no, which is why you cannot replace doctors yet and the reason why "90% of diagnoses are made on patient history".

Re: Deep learning outperformed dermatologists in melanoma image classification task

#30

As always, let's see how well it does in live images. This system outperformed dermatologists on its own validation set of 100 images, which I would encourage you to interpret as "heartening preliminary evidence" but not much more. Posting high scores on your validation set is only as informative as your val set is representative of the real world. 70% specificity, 84% sensitivity looks OK on paper (maybe -- as anoth…

First off, if I'm reading correctly, it outperformed on its test set. This is different as it doesn't get to see that at any point before it's final.

If the authors have done a diligent job here, that should be good evidence of it's accuracy. It's also encouraging to see they do multiple training runs, getting similar accuracy, and that their ROC is generally better than not just the average physician, but almost all.

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