Calculation of brain elastic parameters in vivo

Abstract

In an earlier study [Am. J. Physiol. 232 (Regulatory Integrative Comp. Physiol. 1): R27-R30, 1977], we defined the concept of brain elastic response in vivo as measured by a pressure-depth ratio (G0) derived from a graphic analysis of the elastic response tests. These tests have shown that brain elastic response in vivo is sensitive to changes in the intracranial system and that the response is nonlinear. In this study we identify a second parameter, G0, a second-order pressure-depth ratio that characterizes the nonlinear behavior and, along with G0, can be evaluated from a mathematical relation that models the experimental results obtained from the elastic response test. The equation is a logarithmic function relating the pressure and the subpial insertion depth. From this we obtain G0 and G0 as the slope and curvature of the response function at the subpial position. In animal experiments we correlated the changes in these parameters with those of cerebral hemodynamics during hemorrhagic and drug-induced hypotension. The calculated values of G0 and G0 are reproducible and reflect changes in cerebral blood flow and/or volume.

Patient-specific non-linear finite element modelling for predicting soft organ deformation in real-time; Application to non-rigid neuroimage registration

“…For tumour, we used the Young’s modulus two times larger than for the parenchyma, which is consistent with the experimental data of Sinkus et al (2005). There is strong experimental evidence that the brain tissue is (almost) incompressible (Pamidi and Advani, 1978; Sahay et al, 1992; Walsh and Schettini, 1984) so that we used the Poisson’s ratio of 0.49 for the parenchyma and tumour. Following Wittek et al (2007), the ventricles were assigned the properties of a very soft compressible elastic solid with Young’s modulus of 10 Pa and Poisson’s ratio of 0.1 to account for possibility of leakage of the cerebrospinal fluid from the ventricles during surgery.…”

Method of testing very soft biological tissues in compression

“…Therefore, they may be assumed to be initially isotropic (see e.g. Pamidi and Advani, 1978;Walsh and Schettini, 1984;Sahay et al, 1992;Mendis et al, 1995;Miller and Chinzei, 1997;Farshad et al, 1999;Miller, 1999Miller, , 2000Bilston et al, 2001, Miller andChinzei, 2002). Prange and Margulies (2002) report anisotropic properties of brain tissue.…”

Initial in-vivo analysis of 3D heterogeneous brain computations for model-updated image-guided neurosurgery

“…Unfortunately, only a modest amount of data on brain tissue mechanical properties has been reported in the literature. Early studies used mechanical devices to measure properties in vivo but were semi-quantitative at best [11]. A new and exciting area of research has emerged using MR and ultrasound to image transverse strain waves thereby allowing the calculation of regional mechanical properties based on strain measurements [12].…”