Conductivity Anisotropy Influence on Acoustic Sources for Magnetoacoustic Tomography With Magnetic Induction

Yu, Zhengfeng; Dai, Si-Jie; Ma, Qingyu; Guo, Gepu; Tu, Juan; Zhang, Dong

doi:10.1109/tbme.2018.2805697

Cited by 4 publications

(6 citation statements)

References 29 publications

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“…The right part of Eq. (18) is similar to the expression of the electrode detection mode deduced by [5]- [7]. Except that the static magnetic field B s is frequency independent, such that all field quantities are functions of angular frequency ω and space point r. Now, by considering Gauss' theorem, Eq.…”

Section: Reciprocity Theoremmentioning

confidence: 62%

“…Subsequently, Some scholars used disk multiple layer coils to measure the magnetic field intensity generated [14]. When MAET-MI is compared with MAT-MI [11], ultrasound excitation and electromagnetic signal detection steps are employed for the sake of safety; compared to the traditional MAET method that detects signals by electrodes [7], [8], the simple operations of MAT-MI benefits from the separated coils for non-contact detection. Furthermore, compared with EIT and MAT, the resolution of MAET-MI can reach the orders of magnitude of acoustic waves, which is significantly higher than EIT and MAT.…”

Section: Is Limited Bymentioning

confidence: 99%

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Study on Reciprocal Models for Magneto-Acousto-Electrical Tomography With Coil Detection

Gong

Yang

et al. 2019

IEEE Access

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Magneto-Acousto-Electric Tomography with coil detection, known as Magneto-Acousto-Electric Tomography with Magnetic Induction (MAET-MI), is a non-contact resistivity-based imaging method that employs a coil to detect the induced current generated by the ultrasound in biological tissue, which lie under a static magnetic field. To reconstruct an image of the tissue's conductivity, we propose a reciprocal model to describe the relationship between the inducted voltage of a coil and its conductivity. Previous work on the reciprocal theorem demonstrates that reconstructing conductivity using this method is effective. The forward and inverse problem are usually not verified both numerically and experimentally. In this paper, different approaches are adopted to calculate the forward and the inverse problems for verification of the reciprocal model. This verifies that the reconstruction method based on electrode detection can be applied to MAET-MI. This means that the inverse problem of MAET-MI can be transformed into an inverse source reconstruction of a wave equation based on the coil detection. In the forward problem, the moment method is employed to calculate the Radon transform and generate the ultrasonic signals. For the inverse problem, the filtered back projection method is chosen to reconstruct the ultrasound sources, which are related to the curl of the current density in the reciprocal process. Based on the curl of the current density in the reciprocal process, four sets of correlation coefficients of the original and reconstructed images' model are all greater than 90%. The uniform error criterion is obtained via multiple reconstructions and comparison of multiple models. The reciprocal model exhibits a good uniformity and stability when describing the actual physical process. It also provides additional effective ideas for solving the inverse problem quickly to reconstruct the ultrasonic sources, which is corresponding to the actual distribution of the conductivity. INDEX TERMS MAET-MI, forward problem, filtered back projection method, reciprocity theorem.

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Section: Reciprocity Theoremmentioning

confidence: 62%

Section: Is Limited Bymentioning

confidence: 99%

Study on Reciprocal Models for Magneto-Acousto-Electrical Tomography With Coil Detection

Gong

Yang

et al. 2019

IEEE Access

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“…Considering the irregular conductivity distribution problem, a mathematical framework and an optimal control method for reconstructing the anisotropic conductivity tensor were proposed by the Ecole Normale Supérieure de Paris [7] , which proved the convergence of the algorithm. Researchers from the Nanjing Normal University theoretically derived a MAT-MI for a single-layer cylindrical model under an anisotropic conductivity tensor and analyzed its effect [8][9][10][11] . For cylindrical models with abrupt changes in the conductivity boundary, the signal generated at the boundary was demonstrated to be determined by the components of the anisotropic conductivity tensor along the x and y directions.…”

Section: Magnetoacoustic Tomographymentioning

confidence: 99%

A Review on the Coupled Method of Using the Magnetic and Acoustic Fields for Biological Tissue Imaging

Liu

2023

Chin. J. Electr. Eng.

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Magnetic field and acoustic field coupled imaging methods mainly include magnetoacoustic tomography, magneto-acousto-electrical tomography, and thermoacoustic tomography, all of which non-invasively achieve the electrical conductivity imaging of tissues with a resolution of up to the millimeter scale. The principles of these three imaging methods and the research progress in the last two decades are reviewed. First, the principles of the three magnetic and acoustic field coupled methods are individually introduced. The progress in medical electromagnetic imaging is further elaborated, and finally the future directions and summary of the coupled imaging methods are summarized.

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“…In the past decades, several promising technologies of the electrical impendence tomography (EIT), 4,5 magnetic induction tomography (MIT), 6,7 and magnetic resonance electrical impendence tomography (MREIT) [8][9][10] have been developed. However, the practical application still suffers from the shielding effect 5 of insulating media, the high level of current injections, 5 the limited number of electrical electrodes, and the poor spatial or temporal resolutions of image reconstructions, 11,12 and so on. Based on the multi-physics coupling of the magnetic, acoustic and electrical fields, magnetoacoustic tomography with magnetic induction (MAT-MI) [11][12][13][14] has attracted more and more attentions.…”

Section: Introductionmentioning

confidence: 99%

“…However, the practical application still suffers from the shielding effect 5 of insulating media, the high level of current injections, 5 the limited number of electrical electrodes, and the poor spatial or temporal resolutions of image reconstructions, 11,12 and so on. Based on the multi-physics coupling of the magnetic, acoustic and electrical fields, magnetoacoustic tomography with magnetic induction (MAT-MI) [11][12][13][14] has attracted more and more attentions. Whereas, it is still restricted by the required high-frequency high-current excitation and the low-level signal-to-noise ratio (SNR) of signal detections for biological tissues.…”

Section: Introductionmentioning

confidence: 99%

General principle and optimization of magneto‐acousto‐electrical tomography based on image distortion evaluation

Chen

Guo

et al. 2023

Medical Physics

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Background: As a novel non-invasive multi-physics imaging methodology, the magneto-acousto-electrical (MAE) technology is capable of detecting electric conductivity changes for biological tissues, exhibiting prosperous perspectives in medical applications. However, the acoustic beam was often simplified to a straight line or a focused one, being perpendicular to layered boundaries of tissues in previous studies. Linear-scanning measurements were carried out to reconstruct B-mode MAE images for layered models without considering the radiation pattern of transducers. Obvious image distortions in both shape and brightness were observed in experiments without any reasonable explanation. Purpose: This study aims to establish a general physical model for MAE measurements and solve the problem of B-mode image distortion, and hence provide theoretical and technical supports for the improvement of MAE imaging in practical applications. Methods: By considering the radiation pattern of actual transducers and the inclined angle of electric conductivity boundaries, a general principal of MAE measurements applicable for objects of arbitrary shapes is proposed based on the theories of acoustic radiation, Hall Effect and electrical detection. The influences of inclined conductivity boundaries and transducer directivities are numerically analyzed with Matlab programming and also demonstrated by experimental measurements. To evaluate the degree of B-mode image distortion, the deformation length (3 dB amplitude decrease) of approximate straight lines for a circular model is defined as L = dtan(β m /2), with d and β m being the measurement distance and the half radiation angle of the main-lobe, respectively. The rotary-scanning-based MAE tomography (MAET) is employed to reduce the image distortion, and the rotation angle step is further optimized based on the criterion of the boundary radius fluctuation coefficient <0.01 mm. Results:The experimental results of MAE signals and B-mode images as well as MAETs show good agreements with simulations. It is demonstrated that, as the increase of the inclined angle, the MAE decreases rapidly with an extended time interval and reaches the 20 dB amplitude decrease when the angle exceeds 12 • . Meanwhile, the deformation length of B-mode MAE imaging increases with the increase of the radiation angle for the transducer with a weaker radiation pattern, and hence results in a more serious image distortion. A smaller rotation angle step should be adopted to the MAET system with a longer deformation length, and the optimized maximum angle step of 12 • is also achieved for the omnidirectional radiation of point sources with a long deformation length.

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Conductivity Anisotropy Influence on Acoustic Sources for Magnetoacoustic Tomography With Magnetic Induction

Abstract: The favorable results provide a new method for anisotropic conductivity measurement, and suggest the application potential of MAT-MI in biomedical imaging and nondestructive testing for conductivity anisotropic tissues.

Cited by 4 publications

References 29 publications

Study on Reciprocal Models for Magneto-Acousto-Electrical Tomography With Coil Detection

Study on Reciprocal Models for Magneto-Acousto-Electrical Tomography With Coil Detection

A Review on the Coupled Method of Using the Magnetic and Acoustic Fields for Biological Tissue Imaging

General principle and optimization of magneto‐acousto‐electrical tomography based on image distortion evaluation

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