Doctors diagnose diseases as if recognizing objects

brain scans showed that the diagnostic accuracy of X-rays involves the same mechanisms as recognizing everday objects

In medical practice, doctors often make a diagnosis of a disease within minutes of contact with a patient, and sometimes even before the patient reported symptoms. When, for example, a physician encounters a patient with jaundice (yellowing of the skin and whites of the eyes), a diagnosis related to liver disease or dysfunction comes to mind immediately and automatically.

Diagnosis of the disease is a specialized type of problem solving, which are believed to require little or no analytical reasoning. Instead, it is probably based on the fast retrieval of similar cases from memory and, as such, was compared to the pattern recognition. A new study provides evidence that medical diagnoses involve the same brain systems to recognize and name everyday objects.

Marcio Melo of the University of São Paulo and his colleagues, in collaboration with Karl Friston and Cathy Price of the Wellcome Trust Centre for Neuroimaging in London, recruited 25 Brazilian radiologists and scanned the brain when they saw a series of 60 different chest X-rays. 20 images contained clearly identifiable symptoms and diseases easily diagnosed as pneumonia, and 20 had pictures of an animal embedded in radiography. The remaining images received a letter embedded in them, and served as controls.

Previous work has shown that the X-ray scanning radiologists in detail and identify a set abnormalities in about one second to see the first image. They do this by changing the "to find" strategy in which the global properties of the image are evaluated. This second strategy is considered similar to the process by which one recognizes the face and improves with the Experience: the most experienced radiologist takes less time to devote to the analysis of an image, which can contribute to their experience.

This series of experiments were designed to prevent participants from the X-ray analysis in detail, because it is likely to have influenced the results. Animals and letters have been incorporated in radiographic images so that all target stimuli are presented in the same context. Each image was presented for 3.5 seconds, during which the participants had to locate the target, and then recognize the name. Confirming previous studies, results showed that participants can identify abnormalities on radiographs to reach an accurate diagnosis quickly. On average, it took only 1.3 seconds after seeing the images, suggesting that the process is actually performed automatically.

Basically, three types of tests produced the same pattern of activation in a distributed set of brain regions, but at different levels (above). Diagnosis of disease caused a higher level of activation of the nomenclature of the animals, which in turn produces an activation level of the names of the letters. The activation of the prefrontal cortex was greater during diagnostic testing, which involves more associations between words and their meanings, while the visual cortex was more active during animal studies of naming.

This suggests that the brain mechanisms that underlie the immediate recognition of medical radiographic abnormalities are very similar to those underlying the appointment of everyday objects. The increased activation of prefrontal cortical areas shows that the recognition of symptoms is more demanding than naming objects, however, and this is probably because the diagnosis involves the selection of a more appropriate name than the appointment of an animal.

The researchers note that the X-rays used in the study showed relatively common anomalies with which most radiologists are familiar, and that the hypothesis should be tested in other medical specialties that have much expanded clinical visual symptoms such as dermatology. Diagnoses that are less dependent on visual cues, you can use different mechanisms.

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