liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 21 of 21
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Modeling and Simulation of Microdialysis in the Deep Brain Structures2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Microdialysis is a method for monitoring of the local biochemical environment in a region of interest. The method uses a catheter, mimicking the function of a blood capillary, to sample substances from the surrounding medium through diffusion. A recent application for microdialysis is the sampling of neuroactive substances in the deep brain, or basal ganglia, during deep brain stimulation (DBS) for patients with Parkinson’s disease. The basal ganglia consist of nuclei interconnected by chemical synapses, and it is hypothesized that the levels of neurotransmitter substances around the synapses are affected by DBS treatment. In order to relate the microdialysis data to their anatomical origin and to the effects of DBS, it is suitable to estimate the tissue volume which is sampled during a microdialysis experiment. In this thesis, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated and evaluated using the finite element method (FEM), to allow interpretation of biochemical data in relation to anatomical structures.

    A FEM model for simulation of the TVImax for a microdialysis catheter placed in grey brain matter was set up, using Fick’s law of diffusion. The model was used to investigate the impact of the analyte diffusion coefficient (D), the tissue tortuosity (λ) and the loss rate constant (k) on the size of the TVImax by regression analysis. Using relevant parameter intervals, the radius of the TVImax of a neurotransmitter was estimated to 0.85 ± 0.25 mm. A microdialysis experiment on calf brain tissue showed agreement with the regression model. A heterogeneous anisotropic FEM model based on diffusion tensor imaging (DTI) showed that the radius of the TVImax may vary by up to 0.5 mm as a consequence of local tissue properties, which was reasonable in relation to the 95% confidence interval from the regression estimation. The TVImax was simulated and patient-specifically visualized in relation to MRI images for four patients undergoing microdialysis in parallel to DBS. The size of the TVImax showed to be relevant in relation to the basal ganglia nuclei, and the obtained microdialysis data indicated that the biochemical response to DBS depends on the catheter position. The simulations of the TVImax were combined with patient-specific DBS electric field simulations, for further interpretation of the results in relation to the effects of DBS.

    In conclusion, simulations and visualizations of the TVImax allowed relating microdialysis data to its anatomical origin. Detailed knowledge about the parameters affecting the microdialysis sampling volume is valuable for the current application as well as other applications related to the migration of analytes in tissue.

    List of papers
    1. A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis
    Open this publication in new window or tab >>A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis
    Show others...
    2011 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 49, no 12, p. 1459-1469Article in journal (Refereed) Published
    Abstract [en]

    Microdialysis can be used in parallel to deep brain stimulation (DBS) to relate biochemical changes to the clinical outcome. The aim of the study was to use the finite element method to predict the tissue volume of influence (TVI(max)) and its cross-sectional radius (r (TVImax)) when using brain microdialysis, and visualize the TVI(max) in relation to patient anatomy. An equation based on Fick's law was used to simulate the TVI(max). Factorial design and regression analysis were used to investigate the impact of the diffusion coefficient, tortuosity and loss rate on the r (TVImax). A calf brain tissue experiment was performed to further evaluate these parameters. The model was implemented with pre-(MRI) and post-(CT) operative patient images for simulation of the TVI(max) for four patients undergoing microdialysis in parallel to DBS. Using physiologically relevant parameter values, the r (TVImax) for analytes with a diffusion coefficient D = 7.5 × 10(-6) cm(2)/s was estimated to 0.85 ± 0.25 mm. The simulations showed agreement with experimental data. Due to an implanted gold thread, the catheter positions were visible in the post-operative images. The TVI(max) was visualized for each catheter. The biochemical changes could thereby be related to their anatomical origin, facilitating interpretation of results.

    Place, publisher, year, edition, pages
    Springer Publishing Company, 2011
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-72911 (URN)10.1007/s11517-011-0841-0 (DOI)000297550600012 ()22081236 (PubMedID)
    Available from: 2011-12-09 Created: 2011-12-09 Last updated: 2018-01-12Bibliographically approved
    2. Simulations and visualizations for interpretation of brain microdialysis data during deep brain stimulation
    Open this publication in new window or tab >>Simulations and visualizations for interpretation of brain microdialysis data during deep brain stimulation
    Show others...
    2012 (English)In: IEEE Engineering in Medicine and Biology Society (EMBC), 2012, IEEE , 2012, p. 6438-6441Conference paper, Published paper (Refereed)
    Abstract [en]

    Microdialysis of the basal ganglia was used in parallel to deep brain stimulation (DBS) for patients with Parkinson’s disease. The aim of this study was to patientspecifically simulate and visualize the maximum tissue volume of influence (TVImax) for each microdialysis catheter and the electric field generated around each DBS electrode. The finite element method (FEM) was used for the simulations. The method allowed mapping of the anatomical origin of the microdialysis data and the electric stimulation for each patient. It  was seen that the sampling and stimulation targets differed among the patients, and the results will therefore be used in the future interpretation of the biochemical data.

    Place, publisher, year, edition, pages
    IEEE, 2012
    Series
    IEEE Engineering in Medicine and Biology Society Conference Proceedings, ISSN 1557-170X
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84275 (URN)10.1109/EMBC.2012.6347468 (DOI)000313296506155 ()23367403 (PubMedID)9781424441198 (ISBN)9781424441204 (ISBN)9781457717871 (ISBN)
    Conference
    34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2012), 28 August - 1 September 2012, San Diego, CA, USA
    Available from: 2012-10-03 Created: 2012-10-03 Last updated: 2018-01-12Bibliographically approved
    3. The effect of tissue heterogeneity and anisotropy on microdialysis of the deep brain
    Open this publication in new window or tab >>The effect of tissue heterogeneity and anisotropy on microdialysis of the deep brain
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Microdialysis of the basal ganglia was recently used to study changes of neurotransmitter levels in relation to deep brain stimulation (DBS). In order to estimate the anatomical origin of the microdialysis data, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated and visualized using the finite element method (FEM). In the current study the impact of brain heterogeneity and anisotropy on the TVImax was investigated, using diffusion tensor imaging (DTI) to create a second-order tensor model of the basal ganglia. The results were presented using descriptive statistics, indicating that the mean radius of the TVImax varied by up to 0.5 mm (n = 98444) for FEM simulations based on DTI compared to a homogeneous and isotropic reference model. The internal capsule and subthalamic area showed significantly higher anisotropy (p < 0.0001, n = 600) than the putamen and the globus pallidus, in accordance with theory. It was concluded that the size of the TVImax remained small enough to be relevant in relation to the anatomical structures of interest, and that local tissue properties should be accounted for when relating the microdialysis data to their anatomical targets.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84276 (URN)
    Available from: 2012-10-03 Created: 2012-10-03 Last updated: 2016-05-04Bibliographically approved
  • 2.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    A diffusion tensor-based finite element model of microdialysis in the deep brain2015In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, Vol. 18, no 2, p. 201-212Article in journal (Refereed)
    Abstract [en]

    Microdialysis of the basal ganglia was recently used to study neurotransmitter levels in relation to deep brain stimulation. In order to estimate the anatomical origin of the obtained data, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated using the finite element method. This study investigates the impact of brain heterogeneity and anisotropy on the TVImax using diffusion tensor imaging (DTI) to create a second-order tensor model of the basal ganglia. Descriptive statistics showed that the maximum migration distance for neurotransmitters varied by up to 55% (n = 98,444) for DTI-based simulations compared with an isotropic reference model, and the anisotropy differed between different targets in accordance with theory. The size of the TVImax was relevant in relation to the size of the anatomical structures of interest, and local tissue properties should be accounted for when relating microdialysis data to their anatomical targets.

  • 3.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    The effect of tissue heterogeneity and anisotropy on microdialysis of the deep brainManuscript (preprint) (Other academic)
    Abstract [en]

    Microdialysis of the basal ganglia was recently used to study changes of neurotransmitter levels in relation to deep brain stimulation (DBS). In order to estimate the anatomical origin of the microdialysis data, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated and visualized using the finite element method (FEM). In the current study the impact of brain heterogeneity and anisotropy on the TVImax was investigated, using diffusion tensor imaging (DTI) to create a second-order tensor model of the basal ganglia. The results were presented using descriptive statistics, indicating that the mean radius of the TVImax varied by up to 0.5 mm (n = 98444) for FEM simulations based on DTI compared to a homogeneous and isotropic reference model. The internal capsule and subthalamic area showed significantly higher anisotropy (p < 0.0001, n = 600) than the putamen and the globus pallidus, in accordance with theory. It was concluded that the size of the TVImax remained small enough to be relevant in relation to the anatomical structures of interest, and that local tissue properties should be accounted for when relating the microdialysis data to their anatomical targets.

  • 4.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Didzar, Nil
    Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Biochemical monitoring and simulation of the electric field during deep brain stimulation (oral)2010Conference paper (Other academic)
  • 5.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Dizdar (Dizdar Segrell), Nil
    Linköping University, Department of Clinical and Experimental Medicine, Neurology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Simulations and visualizations for interpretation of brain microdialysis data during deep brain stimulation2012In: IEEE Engineering in Medicine and Biology Society (EMBC), 2012, IEEE , 2012, p. 6438-6441Conference paper (Refereed)
    Abstract [en]

    Microdialysis of the basal ganglia was used in parallel to deep brain stimulation (DBS) for patients with Parkinson’s disease. The aim of this study was to patientspecifically simulate and visualize the maximum tissue volume of influence (TVImax) for each microdialysis catheter and the electric field generated around each DBS electrode. The finite element method (FEM) was used for the simulations. The method allowed mapping of the anatomical origin of the microdialysis data and the electric stimulation for each patient. It  was seen that the sampling and stimulation targets differed among the patients, and the results will therefore be used in the future interpretation of the biochemical data.

  • 6.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Simulation of Deep Brain Stimulation for Tourette's Syndrome (oral)2011Conference paper (Refereed)
  • 7.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Dizdar (Dizdar Segrell), Nil
    Linköping University, Department of Clinical and Experimental Medicine, Neurology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis2011In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 49, no 12, p. 1459-1469Article in journal (Refereed)
    Abstract [en]

    Microdialysis can be used in parallel to deep brain stimulation (DBS) to relate biochemical changes to the clinical outcome. The aim of the study was to use the finite element method to predict the tissue volume of influence (TVI(max)) and its cross-sectional radius (r (TVImax)) when using brain microdialysis, and visualize the TVI(max) in relation to patient anatomy. An equation based on Fick's law was used to simulate the TVI(max). Factorial design and regression analysis were used to investigate the impact of the diffusion coefficient, tortuosity and loss rate on the r (TVImax). A calf brain tissue experiment was performed to further evaluate these parameters. The model was implemented with pre-(MRI) and post-(CT) operative patient images for simulation of the TVI(max) for four patients undergoing microdialysis in parallel to DBS. Using physiologically relevant parameter values, the r (TVImax) for analytes with a diffusion coefficient D = 7.5 × 10(-6) cm(2)/s was estimated to 0.85 ± 0.25 mm. The simulations showed agreement with experimental data. Due to an implanted gold thread, the catheter positions were visible in the post-operative images. The TVI(max) was visualized for each catheter. The biochemical changes could thereby be related to their anatomical origin, facilitating interpretation of results.

  • 8.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Didzar, Nil
    Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A finite element model for biochemical monitoring in the brain during deep brain stimulation (poster)2010Conference paper (Refereed)
  • 9.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Dizdar, Nil
    Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A Finite Model for Biochemical Monitoring in the Brain during Deep Brain Stimulation (oral)2010Conference paper (Refereed)
  • 10.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Software for Patient Specific Modeling and Simulation of Deep Brain Stimulation (poster)2011Conference paper (Refereed)
  • 11.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Foltynie, Thomas
    University College London, UK.
    Limousine, Patricia
    University College London, UK.
    Zrinzo, Ludwig
    University College London, UK.
    Hariz, Marwan
    University College London, UK.
    Patient-specific visualization of the DBS-electric field in Tourette syndrome2012Conference paper (Other academic)
  • 12.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Patient-Specific Modeling and Simulation of Deep Brain Stimulation2011In: Patient-Specific Modeling in Tomorrow's Medicine / [ed] Amit Gefen, Springer Berlin/Heidelberg, 2011, p. 357-378Chapter in book (Refereed)
    Abstract [en]

    Deep brain stimulation (DBS) is widely used for reduction of symptoms caused by movement disorders. In this chapter a patient-specific finite element method for modeling and simulation of DBS electric parameters is presented. The individual’s stereotactic preoperative MR-batch of images is used as input to the model in order to classify tissue type and allot electrical conductivity for cerebrospinal fluid, blood and grey as well as white matter. With patient-specific positioning of the DBS electrodes the method allows for investigation of the relative electric field changes in relation to anatomy and DBS-settings. Examples of visualization of the patient-specific electric entities together with the surrounding anatomy are given. The use of the method is exemplified on patients with Parkinson’s disease. Future applications including multiphysics simulations and applicability for new DBS targets and symptoms are discussed.

  • 13.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Software for patient specific simulation and visualization of electric field around deep brain stimulation electrodes (electronic poster)2011Conference paper (Refereed)
  • 14.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Kefalopoulou, Zinovia
    Unit of Functional Neurosurgery, Institute of Neurology, University College London, London, UK.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Limousin, Patricia
    Unit of Functional Neurosurgery, Institute of Neurology, University College London, London, UK.
    Zrinzo, Ludvic
    Unit of Functional Neurosurgery, Institute of Neurology, University College London, London, UK.
    Hariz, Marwan
    Unit of Functional Neurosurgery, Institute of Neurology, University College London, London, UK / Department of Clinical Neuroscience, Umeå University, Umeå, Sweden.
    Deep Brain Stimulation of the Pallidum Internum for Gilles de la Tourette Syndrome: A Patient-Specific Model-Based Simulation Study of the Electric Field2015In: Neuromodulation (Malden, Mass.), ISSN 1094-7159, E-ISSN 1525-1403, no 2, p. 90-96Article in journal (Refereed)
    Abstract [en]

    Objectives

    The aim of this study was to investigate the deep brain stimulation (DBS) electric field distribution in proton-density MRI scans visualizing the globus pallidus internus (GPi) of patients with Gilles de la Tourette syndrome (GTS), along with its relation to the anatomy.

    Methods

    Patient-specific brain tissue models (n = 7) with bilateral DBS electrodes in the GPi were set up using the finite element method in five patients who had undergone stereotactic proton-density MRI-guided surgery and showed variable improvement with DBS. Simulations (n = 27) of the electric field were performed and the results visualized on the respective preoperative stereotactic MRI scans. The mean electric field volumes (n = 81) within the 0.1, 0.15, and 0.2 V/mm isosurfaces were calculated and compared with the anatomy.

    Results

    Visualization of the simulated electric field confirmed that the anteromedial limbic GPi was the main stimulated target for four of the patients and the posteromedial sensorimotor GPi for one. Larger volumes extended asymmetrically, with parts of fields stretching into the lamina between GPi and globus pallidus externus and into the internal capsule. There was a high correlation (r = 0.994, n = 54) between volumes and brain sides, but with a systematic shift toward the right side, especially for the larger volumes. Simulations with homogeneous tissue models showed no differences.

    Conclusions

    Patient-specific DBS electric field simulations in the GPi as visualized on proton-density MR scans can be implemented in patients with GTS. Visualization of electric fields together with stereotactic thin-slice MRI can provide further support when predicting anatomical structures possibly influenced by DBS in this complex disorder.

  • 15.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Martens, Hubert
    Sapiens Steering Brain Stimulation B.V., The Netherlands.
    Surgical Therapy: Parkinson's disease2014In: Movement DisordersSupplement: Abstracts of the Eighteenth International Congress of Parkinson's Disease and Movement Disorders, John Wiley & Sons, 2014, Vol. 29, p. 1170-1170, article id Suppl 1:1170Conference paper (Other academic)
    Abstract [en]

    Objective: To analyze the relationship between the electric field and the volume of tissue activated (VTA) during model-based investigations of deep brain stimulation (DBS).

    Background: An important factor for the therapeutic outcome of DBS is the spatial distribution of the stimulation field in the target area. Finite element models and simulations of DBS are increasingly being used to study the distribution of the stimulation field in relation to patient specific anatomy. The stimulation field is often defined as a VTA derived from computational axon models that are coupled to the finite element simulations. This approach however, is not feasible in many research centers due to the complexity of developing a computational axon model, as well as the extensive execution time when solving such models.

    Methods: A detailed computer axon cable model was developed to study axonal activation in response to various DBS stimulation configurations. A range of axon models were set up and coupled to finite element models of DBS. DBS simulations were performed for Medtronic lead model 3389 during monopolar configurations for a range of amplitudes and pulse widths. Activation thresholds for the electric fields were derived by measuring the field strength at the maximum radius of activation for each configuration.

    Results: Simulations showed that the electric field thresholds were related to stimulation amplitude, pulse width, and axon diameter. For large axons, the electric field threshold was not dependent on the amplitude, thus implying a low sensitivity of the electric field curvature.

    Conclusions: Electric field thresholds can be used to predict the VTA during model-based investigations of DBS without the necessity of computer axon models. The use of electric field thresholds may substantially simplify the process of performing model-based investigations of DBS in the future.

  • 16.
    Zsigmond, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Nord, M.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Dizdar (Segrell), Nil
    Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Neurotransmitter levels in basal ganglia during L-dopa and Deep Brain Stimulation treatment in Parkinson’s Disease2013Manuscript (preprint) (Other academic)
    Abstract [en]

    Background: Bilateral deep brain stimulation of the nucleus subthalamicus (STN DBS) is a wellestablishedtreatment in patients with advanced Parkinson’s disease (PD). The mechanism bywhich STN DBS improves the PD symptoms remains unclear. In a previous perioperativestudy we have shown that there might be alterations of neurotransmitter levels in the Globuspallidum interna (GPi) during STN DBS. In this study we wanted to examine if STN DBSand L-dopa infusion interact and affect the levels of neurotransmitters.

    Methods: Five patients with advanced PD took part in the study. During STN surgery microdialysis catheters were inserted bilaterally in the GPi and unilaterally in the right putamen. A study protocol was set up and was followed for three days including STN DBS left side, right side and bilateral. L-dopa infusion with and without concomitant bilateral STN DBS was also performed.

    Results: The putaminal dopamine levels increase during STN DBS. In addition an increase of GABA concentrations in the GPi during STN DBS and during L-dopa infusion was found.

    Conclusions: These findings can provide evidence that the STN has a direct action on the substantia nigra pars compacta (SNc) and that STN DBS may indirectly release putaminal dopamine. There is also evidence that STN DBS interferes with L-dopa therapy resulting in higher levels of Ldopa in the brain explaining why its possible to decrease L-dopa medication after DBS surgery.

  • 17.
    Zsigmond, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Nord, Maria
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dizdar (Dizdar Segrell), Nil
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Neurotransmitter levels in basal ganglia during levodopa and deep brain stimulation treatment in Parkinson’s disease2014In: Neurology and Clinical Neuroscience, ISSN 2049-4173, Vol. 2, no 5, p. 149-155Article in journal (Refereed)
    Abstract [en]

    Background The mechanism by which deep brain stimulation of the nucleus subthalamicus improves Parkinson’s disease symptoms remains unclear. In a previous perioperative study, we showed that there might be alterations of neurotransmitter levels in the globus pallidum interna during deep brain stimulation of the nucleus subthalamicus. Aim In this study, we examined whether deep brain stimulation of the nucleus subthalamicus and levodopa infusion interact and affect the levels of neurotransmitters. Methods Five patients with advanced Parkinson’s disease took part in the study. During subthalamic nucleus surgery, microdialysis catheters were inserted bilaterally in the globus pallidum interna and unilaterally in the right putamen. A study protocol was set up and was followed for 3 days. Levodopa infusion with and without concomitant bilateral deep brain stimulation of the nucleus subthalamicus was also carried out. Results The putaminal dopamine levels increased during deep brain stimulation of the nucleus subthalamicus. In addition, an increase of gamma amino buturic acid concentrations in the globus pallidum interna during deep brain stimulation of the nucleus subthalamicus and during levodopa infusion was found. Conclusions These findings provide evidence that the subthalamic nucleus has a direct action on the substantia nigra pars compacta, and that deep brain stimulation of the nucleus subthalamicus might indirectly release putaminal dopamine. There is also evidence that deep brain stimulation of the nucleus subthalamicus interferes with levodopa therapy resulting in higher levels of levodopa in the brain, explaining why it is possible to decrease levodopa medication after deep brain stimulation surgery.

  • 18.
    Zsigmond, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Dizdar, Nil
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Biochemical Monitoring and Simulation of the Electric Field during Deep Brain Stimulation2009Conference paper (Refereed)
  • 19.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology. Sapiens Steering Brain Stimulation BV, NL-5656 Eindhoven, Netherlands.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Martens, Hubert
    Sapiens Steering Brain Stimulation B.V., Eindhoven, The Netherlands.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Relationship between Neural Activation and Electric Field Distribution during Deep Brain Stimulation2015In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 62, no 2, p. 664-72Article in journal (Refereed)
    Abstract [en]

    Models and simulations are commonly used to study deep brain stimulation (DBS). Simulated stimulation fields are often defined and visualized by electric field isolevels or volumes of tissue activated (VTA). The aim of the present study was to evaluate the relationship between stimulation field strength as defined by the electric potential V, the electric field E, and the divergence of the electric field ∇(2) V, and neural activation. Axon cable models were developed and coupled to finite-element DBS models in three-dimensional (3-D). Field thresholds ( VT , ET, and ∇(2) VT ) were derived at the location of activation for various stimulation amplitudes (1 to 5 V), pulse widths (30 to 120 μs), and axon diameters (2.0 to 7.5 μm). Results showed that thresholds for VT and ∇(2) VT were highly dependent on the stimulation amplitude while ET were approximately independent of the amplitude for large axons. The activation field strength thresholds presented in this study may be used in future studies to approximate the VTA during model-based investigations of DBS without the need of computational axon models.

  • 20.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Computational analysis of the electric field during deep brain stimulation (oral, invited)2010Conference paper (Refereed)
  • 21.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Software for patient-specific modeling and simulation of deep brain stimulation (poster)2011Conference paper (Other academic)
1 - 21 of 21
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf