Projects / Programmes
Reconstruction of electrical conductivity of tissues by means of magnetic resonance techniques
| Code |
Science |
Field |
Subfield |
| 2.06.07 |
Engineering sciences and technologies |
Systems and cybernetics |
Biomedical technics |
| Code |
Science |
Field |
| T115 |
Technological sciences |
Medical technology |
| Code |
Science |
Field |
| 2.06 |
Engineering and Technology |
Medical engineering
|
electrical conductivity, magnetic resonance imaging, electroporation
Researchers (13)
Organisations (2)
Abstract
Electrical properties of biological tissues have been of interest for over a century as they determine the pathways of current flow through the body and are therefore important in the analysis of a wide range of biomedical applications. A particular application of electromagnetic fields that gained its attention in recent years is electroporation. It involves exposing biological cells to pulsed electric fields, which results in increased permeability of cell membrane. One of the most important conditions for successful electroporation is the exposure of cells to sufficiently high electric field, which is determined within the tissue mainly by its electrical properties. In order to obtain most appropriate distribution of electric field in the treated tissue, treatment planning is used. Treatment planning already proved to have a great potential in clinical use in medical applications of electroporation. However, its applicability is currently limited due to uncertain conductivity values of the treated areas, especially in tumor tissue. Therefore, new techniques for determining maps of electrical conductivity are needed. Even though different attempts to obtain maps of conductivity distribution of tissues were already reported in the literature, each of them has its own disadvantages; poor spatial resolution in the case of electrical impedance tomography, requirement of current injections in the case of magnetic resonance electrical impedance tomography and limitation to high-frequency conductivity values in the case of Electrical Properties Tomography (EPT). Thus, obtaining quantitative maps of electrical conductivity at sufficient spatial resolution without current injection remains a challenge - a challenge that is addressed by the Conductivity Tensor Imaging (CTI).
The purpose of this project is to implement and validate CTI for measurement of low-frequency electrical conductivity distribution using MRI techniques. It was recently demonstrated that CTI enables reconstruction of low-frequency conductivity tensor images using an MRI scanner without current injections. This new technique could be used to provide patient-specific electrical conductivities for numerical models used in treatment planning of applications of electroporation and also in other medical applications employing electromagnetic fields. Improved treatment plans with patient-specific electrical conductivities will enable better prediction of the treatment outcome, hence safer and more efficient treatments. Still, before CTI implementation in the treatment plan workflow, the method needs to be additionally evaluated. Therefore, in the scope of Work Packages (WP) 1-4 described in the proposed research project, we will evaluate CTI by careful examination of each its components through different imaging experiments on phantoms, ex vivo and in vivo biological tissues using different MRI scanners.
In WP 1, we will implement appropriate imaging sequence for EPT on two MRI systems, each with different Larmor frequency, which will enable us to obtain conductivity distributions at two different frequencies (100 and 400 MHz). Then, in WP 2, we will implement MR diffusion-weighted magnetic resonance imaging, where we will evaluate its performance on biological tissues and phantoms with controllable anisotropy. Finally, in WP 3, we will establish CTI technique by utilizing imaging sequences developed in previous two WPs and by developing numerical algorithm needed for reconstruction of low-frequency electrical conductivity distribution. We will apply CTI for imaging conductivity of tissues in vivo (mouse tumors and muscles) and for reconstruction of conductivity distribution from the images obtained by a clinical MRI scanner. Since the CTI technique is still not very known, we will take special care in WP 4 to disseminate results of the project to the scientific community through different communication channels.
Significance for science
Based on a recent demonstration of feasibility to image electrical conductivity using Conductivity Tensor Imaging (CTI) technique, the project will enable validation and further development of the CTI. Even though the proposed MRI technique is new, its results have already gained considerable attention in the scientific field of biompedance and magnetic resonance imaging. Still, improvement and validation of the technique is needed in order to make it established and efficient. We believe this is achievable through proposed project which will enable us to systematically explore the technique and apply it for measurement of accurate in vivo tissue conductivity that could be used in a numerical model for the treatment planning of electroporation treatments such as electrochemotherapy and irreversible electroporation ablation. In addition to improvement of the accuracy and reliability of numerical models used in electroporation treatment of established targets, such as tumors, patient-specific conductivity values would also accelerate the development of new electroporation treatments. This will also allow us to generate sufficient body of evidence and experience to be able to apply in the near future for larger international project.
Indirect impact of the project for society will be the use of results of the project in undergraduate and postgraduate studies in Slovenia, as well as on international level. Since part of the research will be done at University of Ljubljana, students will be involved in research and their results used in their graduation thesis and doctoral thesis. The research results will be presented at national and international conferences, workshops and in the form of scientific papers. All this will contribute to promotion of Slovenia as a high technological society with innovative knowledge.
Significance for the country
Based on a recent demonstration of feasibility to image electrical conductivity using Conductivity Tensor Imaging (CTI) technique, the project will enable validation and further development of the CTI. Even though the proposed MRI technique is new, its results have already gained considerable attention in the scientific field of biompedance and magnetic resonance imaging. Still, improvement and validation of the technique is needed in order to make it established and efficient. We believe this is achievable through proposed project which will enable us to systematically explore the technique and apply it for measurement of accurate in vivo tissue conductivity that could be used in a numerical model for the treatment planning of electroporation treatments such as electrochemotherapy and irreversible electroporation ablation. In addition to improvement of the accuracy and reliability of numerical models used in electroporation treatment of established targets, such as tumors, patient-specific conductivity values would also accelerate the development of new electroporation treatments. This will also allow us to generate sufficient body of evidence and experience to be able to apply in the near future for larger international project.
Indirect impact of the project for society will be the use of results of the project in undergraduate and postgraduate studies in Slovenia, as well as on international level. Since part of the research will be done at University of Ljubljana, students will be involved in research and their results used in their graduation thesis and doctoral thesis. The research results will be presented at national and international conferences, workshops and in the form of scientific papers. All this will contribute to promotion of Slovenia as a high technological society with innovative knowledge.
Most important scientific results
Interim report
Most important socioeconomically and culturally relevant results
Interim report
