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Potts MR, Bennion NJ, Zappalá S, Marshall D, Harrison R, Evans SL. Fabrication of a positional brain shift phantom through the utilization of the frozen intermediate hydrogel state. J Mech Behav Biomed Mater 2023; 140:105704. [PMID: 36801778 DOI: 10.1016/j.jmbbm.2023.105704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 01/10/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023]
Abstract
Synthetic models (phantoms) of the brain-skull system are useful tools for the study of surgical events that are otherwise difficult to study directly in humans. To date, very few studies can be found which replicate the full anatomical brain-skull system. Such models are required to study the more global mechanical events that can occur in neurosurgery, such as positional brain shift. Presented in this work is a novel workflow for the fabrication of a biofidelic brain-skull phantom which features a full hydrogel brain with fluid-filled ventricle/fissure spaces, elastomer dural septa and fluid-filled skull. Central to this workflow is the utilization of the frozen intermediate curing state of an established brain tissue surrogate, which allows for a novel moulding and skull installation approach that permits a much fuller recreation of the anatomy. The mechanical realism of the phantom was validated through indentation testing of the phantom's brain and simulation of the supine to prone brain shift event, while the geometric realism was validated through magnetic resonance imaging. The developed phantom captured a novel measurement of the supine to prone brain shift event with a magnitude that accurately reproduces that seen in the literature.
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Affiliation(s)
| | | | - Stefano Zappalá
- School of Computer Science and Informatics, Cardiff University, Cardiff, UK
| | - David Marshall
- School of Computer Science and Informatics, Cardiff University, Cardiff, UK
| | | | - Sam L Evans
- School of Engineering, Cardiff University, Cardiff, UK
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2
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Prakash R, Yamamoto KK, Oca SR, Ross W, Codd PJ. Brain-Mimicking Phantom for Photoablation and Visualization. ... INTERNATIONAL SYMPOSIUM ON MEDICAL ROBOTICS. INTERNATIONAL SYMPOSIUM ON MEDICAL ROBOTICS 2023; 2023:10.1109/ismr57123.2023.10130243. [PMID: 37274088 PMCID: PMC10237535 DOI: 10.1109/ismr57123.2023.10130243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
While the use of tissue-mimicking (TM) phantoms has been ubiquitous in surgical robotics, the translation of technology from laboratory experiments to equivalent intraoperative tissue conditions has been a challenge. The increasing use of lasers for surgical tumor resection has introduced the need to develop a modular, low-cost, functionally relevant TM phantom to model the complex laser-tissue interaction. In this paper, a TM phantom with mechanically and thermally similar properties as human brain tissue suited for photoablation studies and subsequent visualization is developed. The proposed study demonstrates the tuned phantom response to laser ablation for fixed laser power, time, and angle. Additionally, the ablated crater profile is visualized using optical coherence tomography (OCT), enabling high-resolution surface profile generation.
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Affiliation(s)
- Ravi Prakash
- Department of Mechanical Engineering and Materials Science, Duke University
| | - Kent K. Yamamoto
- Department of Mechanical Engineering and Materials Science, Duke University
| | - Siobhan R. Oca
- Department of Mechanical Engineering and Materials Science, Duke University
| | - Weston Ross
- Department of Neurosurgery, Duke University School of Medicine
| | - Patrick J. Codd
- Department of Mechanical Engineering and Materials Science, Duke University
- Department of Neurosurgery, Duke University School of Medicine
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3
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Kainz MP, Greiner A, Hinrichsen J, Kolb D, Comellas E, Steinmann P, Budday S, Terzano M, Holzapfel GA. Poro-viscoelastic material parameter identification of brain tissue-mimicking hydrogels. Front Bioeng Biotechnol 2023; 11:1143304. [PMID: 37101751 PMCID: PMC10123293 DOI: 10.3389/fbioe.2023.1143304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/27/2023] [Indexed: 04/28/2023] Open
Abstract
Understanding and characterizing the mechanical and structural properties of brain tissue is essential for developing and calibrating reliable material models. Based on the Theory of Porous Media, a novel nonlinear poro-viscoelastic computational model was recently proposed to describe the mechanical response of the tissue under different loading conditions. The model contains parameters related to the time-dependent behavior arising from both the viscoelastic relaxation of the solid matrix and its interaction with the fluid phase. This study focuses on the characterization of these parameters through indentation experiments on a tailor-made polyvinyl alcohol-based hydrogel mimicking brain tissue. The material behavior is adjusted to ex vivo porcine brain tissue. An inverse parameter identification scheme using a trust region reflective algorithm is introduced and applied to match experimental data obtained from the indentation with the proposed computational model. By minimizing the error between experimental values and finite element simulation results, the optimal constitutive model parameters of the brain tissue-mimicking hydrogel are extracted. Finally, the model is validated using the derived material parameters in a finite element simulation.
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Affiliation(s)
- Manuel P. Kainz
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
| | - Alexander Greiner
- Department Mechanical Engineering, Institute of Applied Mechanics, Friedrich Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Jan Hinrichsen
- Department Mechanical Engineering, Institute of Applied Mechanics, Friedrich Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Dagmar Kolb
- Center for Medical Research, Gottfried Schatz Research Center, Core Facility Ultrastructure Analysis, Medical University of Graz, Graz, Austria
- Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Ester Comellas
- Department of Physics, Serra Húnter Fellow, Universitat Politècnica de Catalunya (UPC), Barcelona, Spain
| | - Paul Steinmann
- Department Mechanical Engineering, Institute of Applied Mechanics, Friedrich Alexander-University Erlangen-Nürnberg, Erlangen, Germany
- Glasgow Computational Engineering Centre, University of Glasgow, Glasgow, United Kingdom
| | - Silvia Budday
- Department Mechanical Engineering, Institute of Applied Mechanics, Friedrich Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Michele Terzano
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
| | - Gerhard A. Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
- Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
- *Correspondence: Gerhard A. Holzapfel,
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Kilian D, Kilian W, Troia A, Nguyen TD, Ittermann B, Zilberti L, Gelinsky M. 3D Extrusion Printing of Biphasic Anthropomorphic Brain Phantoms Mimicking MR Relaxation Times Based on Alginate-Agarose-Carrageenan Blends. ACS APPLIED MATERIALS & INTERFACES 2022; 14:48397-48415. [PMID: 36270624 PMCID: PMC9634698 DOI: 10.1021/acsami.2c12872] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
The availability of adapted phantoms mimicking different body parts is fundamental to establishing the stability and reliability of magnetic resonance imaging (MRI) methods. The primary purpose of such phantoms is the mimicking of physiologically relevant, contrast-creating relaxation times T1 and T2. For the head, frequently examined by MRI, an anthropomorphic design of brain phantoms would imply the discrimination of gray matter and white matter (WM) within defined, spatially distributed compartments. Multichannel extrusion printing allows the layer-by-layer fabrication of multiple pastelike materials in a spatially defined manner with a predefined shape. In this study, the advantages of this method are used to fabricate biphasic brain phantoms mimicking MR relaxation times and anthropomorphic geometry. The printable ink was based on purely naturally derived polymers: alginate as a calcium-cross-linkable gelling agent, agarose, ι-carrageenan, and GdCl3 in different concentrations (0-280 μmol kg-1) as the paramagnetic component. The suggested inks (e.g., 3Alg-1Agar-6Car) fulfilled the requirements of viscoelastic behavior and printability of large constructs (>150 mL). The microstructure and distribution of GdCl3 were assessed by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX). In closely monitored steps of technological development and characterization, from monophasic and biphasic samples as printable inks and cross-linked gels, we describe the construction of large-scale phantom models whose relaxation times were characterized and checked for stability over time.
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Affiliation(s)
- David Kilian
- Centre
for Translational Bone, Joint and Soft Tissue Research, Faculty of
Medicine Carl Gustav Carus, Technische Universität
Dresden (TUD), Dresden01307, Germany
| | - Wolfgang Kilian
- Physikalisch-Technische
Bundesanstalt (PTB), Berlin10587, Germany
| | - Adriano Troia
- Istituto
Nazionale di Ricerca Metrologica (INRiM), Turin10135, Italy
| | - Thanh-Duc Nguyen
- Centre
for Translational Bone, Joint and Soft Tissue Research, Faculty of
Medicine Carl Gustav Carus, Technische Universität
Dresden (TUD), Dresden01307, Germany
| | - Bernd Ittermann
- Physikalisch-Technische
Bundesanstalt (PTB), Berlin10587, Germany
| | - Luca Zilberti
- Istituto
Nazionale di Ricerca Metrologica (INRiM), Turin10135, Italy
| | - Michael Gelinsky
- Centre
for Translational Bone, Joint and Soft Tissue Research, Faculty of
Medicine Carl Gustav Carus, Technische Universität
Dresden (TUD), Dresden01307, Germany
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Transport in the Brain Extracellular Space: Diffusion, but Which Kind? Int J Mol Sci 2022; 23:ijms232012401. [PMID: 36293258 PMCID: PMC9604357 DOI: 10.3390/ijms232012401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/10/2022] [Accepted: 10/12/2022] [Indexed: 11/17/2022] Open
Abstract
The mechanisms of transport of substances in the brain parenchyma have been a hot topic in scientific discussion in the past decade. This discussion was triggered by the proposed glymphatic hypothesis, which assumes a directed flow of cerebral fluid within the parenchyma, in contrast to the previous notion that diffusion is the main mechanism. However, when discussing the issue of “diffusion or non-diffusion”, much less attention was given to the question that diffusion itself can have a different character. In our opinion, some of the recently published results do not fit into the traditional understanding of diffusion. In this regard, we outline the relevant new theoretical approaches on transport processes in complex random media such as concepts of diffusive diffusivity and time-dependent homogenization, which expands the understanding of the forms of transport of substances based on diffusion.
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Faber J, Hinrichsen J, Greiner A, Reiter N, Budday S. Tissue-Scale Biomechanical Testing of Brain Tissue for the Calibration of Nonlinear Material Models. Curr Protoc 2022; 2:e381. [PMID: 35384412 DOI: 10.1002/cpz1.381] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/14/2022] [Indexed: 06/14/2023]
Abstract
Brain tissue is one of the most complex and softest tissues in the human body. Due to its ultrasoft and biphasic nature, it is difficult to control the deformation state during biomechanical testing and to quantify the highly nonlinear, time-dependent tissue response. In numerous experimental studies that have investigated the mechanical properties of brain tissue over the last decades, stiffness values have varied significantly. One reason for the observed discrepancies is the lack of standardized testing protocols and corresponding data analyses. The tissue properties have been tested on different length and time scales depending on the testing technique, and the corresponding data have been analyzed based on simplifying assumptions. In this review, we highlight the advantage of using nonlinear continuum mechanics based modeling and finite element simulations to carefully design experimental setups and protocols as well as to comprehensively analyze the corresponding experimental data. We review testing techniques and protocols that have been used to calibrate material model parameters and discuss artifacts that might falsify the measured properties. The aim of this work is to provide standardized procedures to reliably quantify the mechanical properties of brain tissue and to more accurately calibrate appropriate constitutive models for computational simulations of brain development, injury and disease. Computational models can not only be used to predictively understand brain tissue behavior, but can also serve as valuable tools to assist diagnosis and treatment of diseases or to plan neurosurgical procedures. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC.
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Affiliation(s)
- Jessica Faber
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Jan Hinrichsen
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Alexander Greiner
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Nina Reiter
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Silvia Budday
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
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Finite Element Model to Reproduce the Effect of Pre-Stress and Needle Insertion Velocity During Infusions into Brain Phantom Gel. Ing Rech Biomed 2021. [DOI: 10.1016/j.irbm.2020.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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