Numerical Experiments on the Contrast Capability of Magnetic Resonance Electrical Property Tomography

• Published in: Magnetic Resonance in Medical Sciences Vol. 19; no. 1; pp. 77 - 85
• Main Authors: Duan, Song, Zhu, Yurong, Liu, Feng, Xin, Sherman Xuegang
• Format: Journal Article
• Language: English
• Published: Japan Japanese Society for Magnetic Resonance in Medicine 01.01.2020; Japan Science and Technology Agency
• Subjects: Biological properties; Brain mapping; Computer Simulation; contrast capability; Electric properties; Electrical resistivity; electromagnetic simulation; Finite element method; Helmholtz equations; Magnetic fields; Magnetic properties; Magnetic resonance; magnetic resonance electrical property tomography; Magnetic Resonance Spectroscopy - methods; Major Paper; Neuroimaging; Permittivity; Phantoms, Imaging; Resonance; Signal to noise ratio; Simulation; Tissues; Tomography; Tomography - methods; Tumors; magnetic resonance electrical property tomography; contrast capability; electromagnetic simulation; signal-to-noise ratio
• ISSN: 1347-3182; 1880-2206
• DOI: 10.2463/mrms.mp.2018-0167

Purpose: Magnetic resonance electrical property tomography (MR EPT) is a technique for non-invasively obtaining the electric property (EP) distribution of biological tissues, with a promising potential for application in the early detection of tumors. However, the contrast capability (CC) of this technique has not been fully studied. This work aims to theoretically explore the CC for detecting the variation of EP values and the size of the imaging region.Methods: A simulation scheme was specifically designed to evaluate the CC of MR EPT. The simulation study has the advantage that the magnetic field can be accurately obtained. EP maps of the designed phantom embedded with target regions of designated various sizes and EPs were reconstructed using the homogeneous Helmholtz equation based on B1+ with different signal-to-noise ratios (SNRs). The CC was estimated by determining the smallest detectable EP contrast when the target region size was as large as the Laplacian kernel and the smallest detectable target region size when the EP contrast was the same as the difference between healthy and malignant tissues in the brain, based on the reconstructed EP maps.Results: Using noise free B1+, the smallest detectable contrastσ and contrastεr were 1% and 3%, respectively, and the smallest detectable target region size was 1 mesh unit (the base unit size used in the simulation) for conductivity and relative permittivity. The smallest detectable EP contrast and target region size were decreased as the B1+ SNR increased.Conclusion: The CC of MR EPT was related with the SNR of the magnetic field. A small EP contrast and size were necessary for detection at a high-SNR magnetic field. Obtaining a high-SNR magnetic field is important for improving the CC of MR EPT.