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These Algorithms Look at X-Rays—and Somehow Detect Your Race

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Thursday, August 5, 2021

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A study raises new concerns that AI will exacerbate disparities in health care. One issue? The study’s authors aren’t sure what cues are used by the algorithms. 

MILLIONS OF DOLLARS are being spent to develop artificial intelligence software that reads x-rays and other medical scans in hopes it can spot things doctors look for but sometimes miss, such as lung cancers. A new study reports that these algorithms can also see something doctors don’t look for on such scans: a patient’s race.

The study authors and other medical AI experts say the results make it more crucial than ever to check that health algorithms perform fairly on people with different racial identities. Complicating that task: The authors themselves aren’t sure what cues the algorithms they created use to predict a person’s race.

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Article based on pre-print manuscript:

Reading Race: AI Recognises Patient's Racial Identity In Medical Images

Imon BanerjeeAnanth Reddy BhimireddyJohn L. BurnsLeo Anthony CeliLi-Ching ChenRamon CorreaNatalie DullerudMarzyeh GhassemiShih-Cheng HuangPo-Chih KuoMatthew P LungrenLyle PalmerBrandon J PriceSaptarshi PurkayasthaAyis PyrrosLuke Oakden-RaynerChima OkechukwuLaleh Seyyed-KalantariHari TrivediRyan WangZachary ZaimanHaoran ZhangJudy W Gichoya

Background: In medical imaging, prior studies have demonstrated disparate AI performance by race, yet there is no known correlation for race on medical imaging that would be obvious to the human expert interpreting the images.
Methods: Using private and public datasets we evaluate: A) performance quantification of deep learning models to detect race from medical images, including the ability of these models to generalize to external environments and across multiple imaging modalities, B) assessment of possible confounding anatomic and phenotype population features, such as disease distribution and body habitus as predictors of race, and C) investigation into the underlying mechanism by which AI models can recognize race.
Findings: Standard deep learning models can be trained to predict race from medical images with high performance across multiple imaging modalities. Our findings hold under external validation conditions, as well as when models are optimized to perform clinically motivated tasks. We demonstrate this detection is not due to trivial proxies or imaging-related surrogate covariates for race, such as underlying disease distribution. Finally, we show that performance persists over all anatomical regions and frequency spectrum of the images suggesting that mitigation efforts will be challenging and demand further study.
Interpretation: We emphasize that model ability to predict self-reported race is itself not the issue of importance. However, our findings that AI can trivially predict self-reported race -- even from corrupted, cropped, and noised medical images -- in a setting where clinical experts cannot, creates an enormous risk for all model deployments in medical imaging: if an AI model secretly used its knowledge of self-reported race to misclassify all Black patients, radiologists would not be able to tell using the same data the model has access to.