Software Toolbox for Low-Frequency Conductivity and Current Density Imaging Using MRI

• Published in: IEEE transactions on biomedical engineering Vol. 64; no. 11; pp. 2505 - 2514
• Main Authors: Sajib, Saurav Z. K., Katoch, Nitish, Kim, Hyung Joong, Kwon, Oh In, Woo, Eung Je
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.11.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Alternating current; Animals; Anisotropy; Applications programs; Brain; Brain - diagnostic imaging; Computer programs; Conductivity; CTI; Current density; Deep brain stimulation; Diagnostic software; Diagnostic systems; Diffusion; Direct current; Dogs; DT-MREIT; Electric Impedance; Electrical impedance; Electrical resistivity; Electroporation; Head - diagnostic imaging; Humans; Image processing; Image Processing, Computer-Assisted - methods; Image reconstruction; Injection; Leg - diagnostic imaging; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Mapping; Mathematical analysis; Mathematical functions; Medical imaging; MRCDI; MRCI toolbox; MREIT; Muscles; Neuroimaging; Phantoms, Imaging; Rats; Resonance; Software; Software development tools; Stimulation; Tensile stress; Tensors; Therapeutic applications; Transcranial Direct Current Stimulation; Conductivity; Tensile stress; Magnetic resonance imaging; Current density; Image reconstruction
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2017.2732502

Objective: Low-frequency conductivity and current density imaging using MRI includes magnetic resonance electrical impedance tomography (MREIT), diffusion tensor MREIT (DT-MREIT), conductivity tensor imaging (CTI), and magnetic resonance current density imaging (MRCDI). MRCDI and MREIT provide current density and isotropic conductivity images, respectively, using current-injection phase MRI techniques. DT-MREIT produces anisotropic conductivity tensor images by incorporating diffusion weighted MRI into MREIT. These current-injection techniques are finding clinical applications in diagnostic imaging and also in transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), and electroporation where treatment currents can function as imaging currents. To avoid adverse effects of nerve and muscle stimulations due to injected currents, conductivity tensor imaging (CTI) utilizes B1 mapping and multi-b diffusion weighted MRI to produce low-frequency anisotropic conductivity tensor images without injecting current. This paper describes numerical implementations of several key mathematical functions for conductivity and current density image reconstructions in MRCDI, MREIT, DT-MREIT, and CTI. Methods: To facilitate experimental studies of clinical applications, we developed a software toolbox for these low-frequency conductivity and current density imaging methods. This MR-based conductivity imaging (MRCI) toolbox includes 11 toolbox functions which can be used in the MATLAB environment. Results: The MRCI toolbox is available at http://iirc.khu.ac.kr/software.html . Its functions were tested by using several experimental datasets, which are provided together with the toolbox. Conclusion: Users of the toolbox can focus on experimental designs and interpretations of reconstructed images instead of developing their own image reconstruction softwares. We expect more toolbox functions to be added from future research outcomes.