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Simulations of radio-frequency lesions with varying brain electrode dimensions
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. (MINT)
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Health Sciences.
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2005 (English)In: 13th Nordic Baltic conference biomedical engineering and medical physics, Umeå, Sweden, 2005, Vol. 9, 62-63 p.Conference paper, Published paper (Refereed)
Abstract [en]

Radio-frequency (RF) lesioning in the

brain was simulated using the finite element method

(FEM). Heating for 60 s with temperature control in

order to keep the tip at 80 °C was simulated. Length,

L, (2 – 4 mm) and diameter, D, (0.5 – 2.5 mm) of the

electrode tip were varied and the resulting lesion

volumes were used to calculate a regression model:

Lesion Volume = – 13.1D + 15.7LD + 13.1D2 mm3.

The results can be useful for electrode design and

prediction of lesion size.

Place, publisher, year, edition, pages
2005. Vol. 9, 62-63 p.
Keyword [en]
Radio-frequency surgery, Brain, Lesion size, Electrode dimensions, Finite Element Method (FEM)
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-13996OAI: oai:DiVA.org:liu-13996DiVA: diva2:22413
Available from: 2006-09-25 Created: 2006-09-25 Last updated: 2017-02-21Bibliographically approved
In thesis
1. Thermocoagulation in Deep Brain Structures: Modelling, simulation and experimental study of radio-frequency lesioning
Open this publication in new window or tab >>Thermocoagulation in Deep Brain Structures: Modelling, simulation and experimental study of radio-frequency lesioning
2006 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Radio-frequency (RF) lesioning is a method utilising high frequency currents for thermal coagulation of pathological tissue or signal pathways. The current is delivered from an electrode with a temperature sensor, permitting control of the current at a desired target temperature. In the brain RF-lesioning can e.g. be used for severe chronic pain and movement disorders such as Parkinson’s disease. This thesis focuses on modelling and simulation with the aim of gaining better understanding and predictability of the lesioning process in deep brain structures. The finite element method (FEM) together with experimental comparisons was used to study the effects of electrode dimensions, electrode target temperature, electric and thermal conductivity of the brain tissue, blood perfusion and cerebrospinal fluid (CSF) filled cysts. Equations for steady current, thermal transport and incompressible flow were used together with statistical factorial design and regression analysis for this purpose.

Increased target temperature, electrode tip length and electrode diameter increased the simulated lesion size, which is in accordance with experimental results. The influence of blood perfusion, modelled as an increase in thermal conductivity in non-coagulated tissue, gave smaller simulated lesions with increasing blood perfusion as heat was more efficiently conducted from the rim of the lesion. If no consideration was taken to the coagulation the lesion became larger with increased thermal conductivity instead, as the increase in conducted heat was compensated for through an increased power output in order to maintain the target temperature. Simulated lesions corresponded well to experimental in-vivo lesions.

The electric conductivity in a homogeneous surrounding had little impact on lesion development. However this was not valid for a heterogeneous surrounding. CSF-filled cysts have a much higher electric conductivity than brain tissue focussing the current to them if the electrode tip is in contact with both. Heating of CSF can also cause considerable convective flow and as a result a very efficient heat transfer. This affected simulated as well as experimental lesion sizes and shapes resulting in both very large lesions if sufficient power compared to the cysts size was supplied and very small lesions if the power was low, mitigating the heat over a large volume.

In conclusion especially blood perfusion and CSF can greatly affect the lesioning process and appear to be important to consider when planning surgical procedures. Hopefully this thesis will help improve knowledge about and predictability of clinical lesioning.

Place, publisher, year, edition, pages
Institutionen för medicinsk teknik, 2006. 44 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1267
Keyword
Neurosurgery, Radiofrequency ablation, Finite element method, Blood perfusion, Cerebrospinal fluid, Free convection
National Category
Surgery
Identifiers
urn:nbn:se:liu:diva-7406 (URN)91-85643-98-X (ISBN)
Presentation
2006-10-12, IMT 1, plan 13, Campus US, Linköpings universitet, Linköping, 00:00 (English)
Opponent
Supervisors
Available from: 2006-09-25 Created: 2006-09-25 Last updated: 2017-02-16Bibliographically approved

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Johansson, Johannes D.Eriksson, OlaWren, JoakimLoyd, DanWårdell, Karin

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