Human model

Head

THE HEAD and more specifically the brain is among the most vital organs of the human body. However, these are not adapted to the dynamical loading conditions involved in modern accidents such as road and sport accidents. The consequences of these extreme loadings are often moderate to severe injuries. Preventing these head injuries is therefore a high priority.

From a mechanical point of view, the biological evolution of the head has lead to a number of integrated protection devices. The scalp and the skull but also to a certain extent the pressurized sub arachnoidal space and the dura matter are natural protections for the brain.

Neck

Despites of recent developments in car passenger protection systems, cervical spine trauma still remain a significant problem. The costs to the society of whiplash-associated disorder (WAD) in the early nineties have been estimated to be 5-10 Billion Euros per Year in Europe.

In many cases, cervical spine trauma is caused by low-speed rear-end impact. More often than not these lesions are benign, but can still generate significant expense.

Soft tissues

Brain MRE

In vivo Elastograms (storage and loss moduli ) of an anesthetized rat brain obtained by Low field MRE Mechanical excitation device on rat head for low field Magnetic Resonance Elastography

The quest for knowledge of the biomechanical behavior of brain tissue has been an essential issue for several decades. Determining the mechanical properties of brain tissue is an essential challenge in numerical modeling of the head.

Before to specify mechanical laws for finite element modeling, rheological properties of brain 

tissue are needed. The results obtained in this way come from two kinds of protocols:

- Most of the results have been obtained through in vitro experimental protocols using classical rheometric techniques

- However recent in vivo studies for brain tissue have been published that use Magnetic Resonance Elastography (MRE). This non invasive technique is based on the coupling of an intra-cerebral shear wave propagating device and a MRI system.

Low field (0.1T) Magnetic Resonance Elastography device

Ex vivo and in vivo characterization of soft tissues including their dynamic behaviour, microscopic components, heterogeneity and anisotropy investigation is an essential topic to develop analytical models and at least more realistic models of the human brain.