Common pigeons can be taught to adeptly diagnose breast cancer using medical slides and X-rays, a new study finds.

With some training and selective food reinforcement, pigeons do just as well as humans in identifying digitised slides and mammograms of cancerous human breast tissue from normal ones, according to researchers at the University of California, Davis and the University of Iowa.

In the study published in the journal PLoS One, the researchers found that the pigeons’ accuracy from day one of training increased from 50 percent to nearly 85 percent by days 13 to 15.

Their findings suggest that pigeons have a remarkable ability to discriminate between complex visual images. This means that the birds could be trained as medical image observers to help researchers explore image quality and the impact of colour, contrast, brightness and image compression artifacts on diagnostic performance.

Although a pigeon’s brain is no bigger than the tip of an index finger, it turns out that it operates in ways very similar to those at work in the human brain, the researchers found. “Their accuracy, like that of humans, was modestly affected by the presence or absence of colour in the images, as well as by degrees of image compression,” said the study’s lead author Richard Levenson, professor of pathology and laboratory medicine at UC Davis Health System.

Levenson’s team collaborated with Edward Wasserman, a professor of psychological and brain sciences at the University of Iowa, after learning about Wasserman’s earlier research on the visual short-term memory capacities of pigeons and people.

For the study, each pigeon learned to discriminate cancerous from non-cancerous images and slides using traditional “operant conditioning,” a technique in which a bird was rewarded only when a correct selection was made. Training with stained pathology slides included a large set of benign and cancerous samples from routine cases at UC Davis Medical Center.

The researchers found that some birds first learned to recognise benign or malignant samples in full colour at low magnification and then progressed to medium and high magnifications. They were also tested using monochrome samples to eliminate colour and brightness as potential cues as well as samples with different levels of image compression, a procedure commonly used to reduce the size of digital data sets.

“The birds were remarkably adept at discriminating between benign and malignant breast cancer slides at all magnifications, a task that can perplex inexperienced human observers,who typically require considerable training to attain mastery,” Levenson said.

However, the pigeons had difficulty evaluating the malignant potential of breast masses detected on mammograms, a task the authors acknowledge as “very challenging." Human radiologists achieved an accuracy rate of about 80 percent when viewing images of the relatively subtle masses used in this study. The pigeons, meanwhile, took many weeks to learn to classify the breast masses in the mammogram training set. Still, it doesn’t discount the fact that pigeons are uncommonly good at distinguishing cancerous from normal breast tissue, the team noted.

Breast cancer, which continues to be a serious health burden globally, is the most commonly diagnosed cancer for young women in Australia, according to the Australian Institute of Health and Welfare. In 2015, 795 women aged 20 to 39 will be diagnosed with breast cancer, while 65 will die from the disease.

Source: YouTube/Victor Navarro

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