Image guided constitutive modeling of the silicone brain phantom

摘要

The goal of this work is to develop reliable constitutive models of the mechanical behavior of the in-vivo human braintissue for applications in neurosurgery. We propose to define the mechanical properties of the brain tissue in-vivo, bytaking the global MR or CT images of a brain response to ventriculostomy – the relief of the elevated intracranialpressure. 3D image analysis translates these images into displacement fields, which by using inverse analysis allow forthe constitutive models of the brain tissue to be developed. We term this approach Image Guided Constitutive Modeling(IGCM). The presented paper demonstrates performance of the IGCM in the controlled environment: on the siliconebrain phantoms closely simulating the in-vivo brain geometry, mechanical properties and boundary conditions. Thephantom of the left hemisphere of human brain was cast using silicon gel. An inflatable rubber membrane was placedinside the phantom to model the lateral ventricle. The experiments were carried out in a specially designed setup in a CTscanner with submillimeter isotropic voxels. The non-communicative hydrocephalus and ventriculostomy weresimulated by consequently inflating and deflating the internal rubber membrane. The obtained images were analyzed toderive displacement fields, meshed, and incorporated into ABAQUS. The subsequent Inverse Finite Element Analysis(based on Levenberg-Marquardt algorithm) allowed for optimization of the parameters of the Mooney-Rivlin non-linearelastic model for the phantom material. The calculated mechanical properties were consistent with those obtained fromthe element tests, providing justification for the future application of the IGCM to in-vivo brain tissue.