Determination of the elasticity parameters of brain tissue with combined simulation and registration

Soza, G; Grosso, R; Nimsky, C; Hastreiter, P; Fahlbusch, R; Greiner, G

doi:10.1581/mrcas.2005.010308

Cited by 17 publications

(18 citation statements)

References 32 publications

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“…Compared with coronary arteries (E ϭ 16.8 kPa, ϭ 0.499), 18 arteries within the brain have different mechanical properties (E ϭ 9.2 kPa, ϭ 0.458). 19 With a lower Young modulus and Poisson ratio, along with differences in the perivascular environment of the intracranial arteries, it can be assumed that larger deformation post-stent placement will occur compared with coronary arteries.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Intracranial Stent Implantation on the Curvature of the Cerebrovasculature

King

Chueh

Bom

et al. 2012

AJNR Am J Neuroradiol

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Section: Discussionmentioning

confidence: 99%

The Effect of Intracranial Stent Implantation on the Curvature of the Cerebrovasculature

King

Chueh

Bom

et al. 2012

AJNR Am J Neuroradiol

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“…from polyimide and parylene) have been developed [13,[19][20][21], reducing the probe stiffness by approximately two orders of magnitude compared to Si. However, as Young's modulus of brain tissue is ∼10 kPa [22][23][24], and the polymer-based probes have a modulus of ∼2.5 GPa, the mechanical mismatch is still considerable. Further, the overall stiffness of the conventional polymerbased probes is too low to penetrate the brain without buckling, unless stiff backbones [13] or gel-filled microfluidic channels are used [21].…”

Section: Introductionmentioning

confidence: 99%

Development of a stimuli-responsive polymer nanocomposite toward biologically optimized, MEMS-based neural probes

Hess

Capadona

Shanmuganathan

et al. 2011

J. Micromech. Microeng.

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This paper reports the development of micromachining processes and mechanical evaluation of a stimuli-responsive, mechanically dynamic polymer nanocomposite for biomedical microsystems. This nanocomposite consists of a cellulose nanofiber network encased in a polyvinyl acetate matrix. Micromachined tensile testing structures fabricated from the nanocomposite displayed a reversible and switchable stiffness comparable to bulk samples, with a Young's modulus of 3420 MPa when dry, reducing to ∼20 MPa when wet, and a stiff-to-flexible transition time of ∼300 s. This mechanically dynamic behavior is particularly attractive for the development of adaptive intracortical probes that are sufficiently stiff to insert into the brain without buckling, but become highly compliant upon insertion. Along these lines, a micromachined neural probe incorporating parylene insulating/moisture barrier layers and Ti/Au electrodes was fabricated from the nanocomposite using a fabrication process designed specifically for this chemical-and temperature-sensitive material. It was found that the parylene layers only slightly increased the stiffness of the probe in the wet state in spite of its much higher Young's modulus. Furthermore, the Ti/Au electrodes exhibited impedance comparable to Au electrodes on conventional substrates. Swelling of the nanocomposite was highly anisotropic favoring the thickness dimension by a factor of 8 to 12, leading to excellent adhesion between the nanocomposite and parylene layers and no discernable deformation of the probes when deployed in deionized water.

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“…While in vivo values strongly depend on frequency, the values used in this work are comparable to those found in in vivo tissues. [50][51][52][53] The results shown in Figs. 4, 5, and 7 and Table II demonstrate the ability of the technique to predict the magnitude of the displacement as well as the overall shape.…”

Section: Discussionmentioning

confidence: 99%

A simulation technique for 3D MR‐guided acoustic radiation force imaging

et al. 2015

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Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green's function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green's function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30-and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028-0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison with experimentally obtained 3D displacement data in homogeneous gelatin phantoms using a 3D MR-ARFI sequence. The agreement of the experimentally measured and simulated results demonstrates the potential to use MR-ARFI displacement data in MRgFUS therapies. C 2015 American Association of Physicists in Medicine. [http://dx

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Determination of the elasticity parameters of brain tissue with combined simulation and registration

Cited by 17 publications

References 32 publications

The Effect of Intracranial Stent Implantation on the Curvature of the Cerebrovasculature

The Effect of Intracranial Stent Implantation on the Curvature of the Cerebrovasculature

Development of a stimuli-responsive polymer nanocomposite toward biologically optimized, MEMS-based neural probes

A simulation technique for 3D MR‐guided acoustic radiation force imaging

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