Abstract
Capturing the deformation of human brain during neurosurgical operations is an extremely important task to improve the accuracy or surgical procedure and minimize permanent damage in patients. This study focuses on the development of an accurate numerical model for the prediction of brain shift during surgical procedures and employs a tissue mimic recently developed to capture the complexity of the human tissue. The phantom, made of a composite hydrogel, was designed to reproduce the dynamic mechanical behaviour of the brain tissue in a range of strain rates suitable for surgical procedures. The use of a well-controlled, accessible and MRI compatible alternative to real brain tissue allows us to rule out spurious effects due to patient geometry and tissue properties variability, CSF amount uncertainties, and head orientation. The performance of different constitutive descriptions is evaluated using a brain–skull mimic, which enables 3D deformation measurements by means of MRI scans. Our combined experimental and numerical investigation demonstrates the importance of using accurate constitutive laws when approaching the modelling of this complex organic tissue and supports the proposal of a hybrid poro-hyper-viscoelastic material formulation for the simulation of brain shift.
Highlights
The human brain undergoes deformation when a craniotomy of considerable size is performed during surgery
Based on consultations with a specialized surgeon, we considered a loss of 60% of cerebrospinal fluid (CSF) an extreme condition during real surgeries; five steps are sufficient for the simulation to cover any possible scenarios
The angular error (AE) converges to a lower value in the subsequent steps, reaching 0.26 and 0.25 rad for the PHVE and PHE, respectively
Summary
The human brain undergoes deformation when a craniotomy of considerable size is performed during surgery. The loss of cerebrospinal fluid (CSF) during surgery, and consequentially of buoyancy forces surrounding the brain, is recognized as the main cause of brain shift (Dumpuri et al 2007; Roberts et al 1998). It has been shown that brain can shift up to twenty millimetres in a non-rigid fashion (Hartkens et al 2003). This introduces a non-negligible error in targets location, which results in lowering the accuracy of surgical procedures. Surgeons try to compensate for brain shift with their own experience, relating locations to anatomical features in order to follow targets inside the brain. Intraoperative magnetic resonance images (MRIs) are used to relocate targets and compensate for excessive deformations (Nimsky et al 2000). There is a need for tools able to accurately predict brain shift pre-operatively and/or offer real-time guidance to the surgeon during the procedures
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