Inspired by seismology, researchers from the French Institute of Health and Medical Research (Inserm) have developed an MRI method to virtually palpate the brain, a crucial step in diagnosis. The approach is a major step forward for brain diseases. But what’s the link between tectonic plates and our brains? How can we palpate the brain without opening the skull?

Physical palpation is often used by doctors during medical examinations to detect structural tissue changes, particularly in regards to elasticity. For example, cancerous tumors often take on the form of nodules that are much harder than the surrounding tissues. This palpation can be replaced by wave propagation techniques. When applied to the body, the varying speeds offer information about organ rigidity. Until now, the brain’s two layers of protection, the skull and cerebrospinal fluid, prevented the use of such procedures in the brain. Brain palpation could only be performed by opening the skull. Research conducted by Stefan Catheline and his team at Inserm has led to the creation of a method inspired by seismology that could be used to avoid this highly invasive procedure, while providing the same information as physical palpation.

But what's the relationship between the study of earthquakes and brain research? Waves. Indeed, like the Earth, our brains emit vibrations generated by blood pulsing through arteries and the circulation of cerebrospinal fluid; these waves can be detected and viewed on a computer screen. In their study (published in the scientific review Proceedings of the National Academy of Sciences of the United States of America), the Inserm researchers managed to detect natural brain vibrations using MRI, and borrowed computational techniques from seismology to represent them on a computer screen. The detection and transcription of these “shear” waves provides an overview of brain elasticity, similar to physical palpation.

This elastography method by magnetic resonance, which records the brain's "soundtrack", could be used to map changes in brain tissue rigidity without the need for biopsy. If tests to improve the detection of brain anomalies and larger scale experiments were to be conducted, this method could play a major role in the detection and analysis of neurodegenerative processes over time.