October 2015 Soft in the head, but how soft?

NUI Galway applied mathematician collaborates with Chinese researchers to find brain matter is softer than a gelatine gel, and may have promising results for neurosurgery

A team of Chinese researchers from Tsinghua University in Beijing has collaborated with an applied mathematician at NUI Galway to measure how soft brain matter really is. The researchers were able to determine that brain matter is extremely soft, even softer than common gelatine. The study appears in the October issue of Biomechanics and Modelling in Mechanobiology.

The research was carried out by generating ‘acoustic beams’ on the surface of the brain, and focusing the beams to interact at a location inside the brain. The interaction amplified the magnitude of the beams and eventually a sound wave was launched in the bulk of a brain. The sound wave was then observed in an ultrafast image through an ultrasound scanner, similar to those used in obstetrics. The speed of the wave was measured, and then related to stiffness of the brain matter through mathematical equations, like the pitch of a plucked string can be related to its tension. The connection between wave speed and stiffness was made through advanced modelling and simulations, which were mainly carried out at NUI Galway.

Professor Michel Destrade, School of Mathematics, Statistics and Applied Mathematics at NUI Galway and affiliated with the International Brain Mechanics and Trauma Lab at Oxford University said: “Previously I had compared the brain to glue by testing cubic samples of the brain. During this study the brain was fully intact and compared to a very, very soft gelatine gel, basically a wobbly liquid.”

Results from the research showed that brain matter is at least three times softer than a gelatine gel. This extreme softness helps explain why brain matter is so susceptible to impacts and rapid accelerations of the head, such as those occurring in sporting accidents, car accidents or following a bomb blast.

The research has promising results for neurosurgery, if it can be used to measure the stiffness of healthy tissue compared to that of brain tumours. At the moment neurosurgeons have to rely on crude estimates to determine the extent of a brain tumour, as it is visually undistinguishable from the surrounding healthy tissue. First they remove a part of the skull to access the brain, and then use finger palpation to estimate how soft or hard a region is, before deciding which part to remove, a procedure which has barely improved in the last 100 years.

For more information contact Professor Michel Destrade, School of Mathematics, Statistics and Applied Mathematics, NUI Galway on michel.destrade@nuigalway.ie or 091 492344.

To view the paper visit http://dx.doi.org/10.1007/s10237-015-0658-0 

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