Optimization of multi-angle Magneto-Acousto-Electrical Tomography (MAET) based on a numerical method

Abstract

<abstract> <p>Magneto-Acousto-Electrical Tomography (MAET) is a novel multi-physics imaging method, which promises to offer a unique biophysical property of tissue electrical impedance with the additional benefit of excellent spatial resolution of the ultrasonic imaging. It opens the potential for early diagnosis of cancer by revealing changes of dielectric characteristics. However, direct MAET is unable to image the irregularly-shaped lesions fully due to the dependence on the angle between conductivity boundary and ultrasound beam direction. In this paper, a numerical simulation of multi-angle MAET is presented for an improved image reconstruction for MAET in order to discern irregularly-shaped tumors in different positions. The results show that the conductivity boundary interfaces are invisible in single angle B-mode reconstructed image, wherever the ultrasound beam and conductivity boundary are nearly parallel. When the multi-angle scanning was adopted, the image reconstructed with image rotation method reproduced the original object pattern. Furthermore, the relationship between reconstruction error and the number of angles was also discussed. It is found that 12 angles would be necessary to achieve nearly the optimal reconstruction. Finally, reconstructed images in <italic>L</italic><sup>2</sup> norm of the error with the measurement noise are presented.</p> </abstract>

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

“…Furthermore, this team analyzed the effect of the number of excitation pulses and the ultrasonic excitation frequency on the longitudinal and vertical resolution of the MAET system and obtained images of the conductivity parameters of isolated pork under optimal experimental conditions [52] . To reconstruct conductivity images of irregular objects, this team proposed an approach with multi-angle scanning, and the relationship between the reconstruction error and number of angles was also presented, demonstrating that an optimal reconstruction can be achieved at 12 angles [53][54] . The team also conducted the Baker encoding excitation system, and achieved isolated tissue imaging [55] .…”

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

“…The objects were placed on a turntable chamber around the vertical axis, and the distribution of conductivity boundaries was reconstructed by the MAE measurement using the combination of 40 linear‐scanning steps and 200 rotation angles. In 2020, to improve the SNR of MAET, a focused transducer 32 was adopted by Sun et al. to excite the phantom model of two elliptically‐shaped tumors.…”

“…Hence, it is impossible to reconstruct B‐mode MAE images accurately in terms of shape and size as well as brightness of conductivity boundaries for objects of arbitrary shapes 31 . Moreover, although the acoustic pressure can be greatly strengthened by a focused transducer, 32 the conductivity gradient cannot be resolved precisely because of the violent pressure change in a small‐sized focal region. Thus, the focused transducer can be applied to the point‐by‐point scanning measurement in two or three dimensions instead of the B‐mode or tomographic imaging.…”

“…Moreover, the radiation pattern of transducers and the inclined angle of conductivity boundaries should be taken into account for the practical application of MAE imaging. In addition, although the MAE attenuation produced at inclined boundaries can be reduced to a certain extent at an appropriate measurement angle by applying the rotary‐scanning‐based MAET, the imaging quality is still affected by the rotation angle step and the transducer radiation pattern 32 . Therefore, to improve the spatial resolution and the SNR for MAET, quantitative analyses based on the mechanism of the generation and detection of MAE signals exhibit their great importance in system optimization and image reconstruction.…”

Research on Factors Affecting the Imaging Resolution of Magneto–Acousto–Electrical Tomography

“…In 2020, a threedimensional mathematical simulation model of MAET was presented, and a three-dimensional image was reconstructed by Li et al [22]. Numerical simulation of multi-angle MAET for improving image reconstruction of MAET was presented by Sun et al [23]. Furthermore, noninvasive modality of treatment-efficacy evaluation for high-intensity focused ultrasound ablation using MAET technology was theoretically investigated by Zhou et al [24].…”