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Cheng Z, Sun Z, Wang J, Jia K. Magneto-acousto-electrical tomography using nonlinearly frequency-modulated ultrasound. Phys Med Biol 2024; 69:085014. [PMID: 38422542 DOI: 10.1088/1361-6560/ad2ee5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 02/29/2024] [Indexed: 03/02/2024]
Abstract
Objective. In this study, nonlinearly frequency-modulated (NLFM) ultrasound was applied to magneto-acousto-electrical tomography (MAET) to increase the dynamic range of detection.Approach. Generation of NLFM signals using window function method-based on the principle of stationary phase-and piecewise linear frequency modulation method-based on the genetic algorithm-was discussed. The MAET experiment systems using spike, linearly frequency-modulated (LFM), or NLFM pulse stimulation were constructed, and three groups of MAET experiments on saline agar phantom samples were carried out to verify the performance-respectively the sensitivity, the dynamic range, and the longitudinal resolution of detection-of MAET using NLFM ultrasound in comparison to that using LFM ultrasound. Based on the above experiments, a pork sample was imaged by ultrasound imaging method, spike MAET method, LFM MAET method, and NLFM MAET method, to compare the imaging accuracy.Main results. The experiment results showed that, through sacrificing very little main-lobe width of pulse compression or equivalently the longitudinal resolution, the MAET using NLFM ultrasound achieved higher signal-to-interference ratio (and therefore higher detection sensitivity), lower side-lobe levels of pulse compression (and therefore larger dynamic range of detection), and large anti-interference capability, compared to the MAET using LFM ultrasound.Significance. The applicability of the MAET using NLFM ultrasound was proved in circumferences where sensitivity and dynamic range of detection were mostly important and slightly lower longitudinal resolution of detection was acceptable. The study furthered the scheme of using coded ultrasound excitation toward the clinical application of MAET.
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Affiliation(s)
- Zhizhuo Cheng
- College of Information and Communication Engineering, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, People's Republic of China
| | - Zhishen Sun
- College of Information and Communication Engineering, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, People's Republic of China
| | - Jianfei Wang
- Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, People's Republic of China
| | - Kebin Jia
- College of Information and Communication Engineering, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, People's Republic of China
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Sun T, Yu M, Yu L, Deng D, Chen M, Lin H, Chen S, Chang C, Chen X. Iterative Reconstruction Algorithms in Magneto-Acousto-Electrical Computed Tomography (MAE-CT) for Image Quality Improvement. IEEE Trans Biomed Eng 2024; 71:669-678. [PMID: 37698962 DOI: 10.1109/tbme.2023.3314617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Magneto-acousto-electrical computed tomography (MAE-CT) is a recently developed rotational magneto-acousto-electrical tomography (MAET) method, which can map the conductivity parameter of tissues with high spatial resolution. Since the imaging mode of MAE-CT is similar to that of CT, the reconstruction algorithms for CT are possible to be adopted for MAE-CT. Previous studies have demonstrated that the filtered back-projection (FBP) algorithm, which is one of the most common CT reconstruction algorithms, can be used for MAE-CT reconstruction. However, FBP has some inherent shortcomings of being sensitive to noise and non-uniform distribution of views. In this study, we introduced iterative reconstruction (IR) method in MAE-CT reconstruction and compared its performance with that of the FBP. The numerical simulation, the phantom, and in vitro experiments were performed, and several IR algorithms (ART, SART, SIRT) were used for reconstruction. The results show that the images reconstructed by the FBP and IR are similar when the data is noise-free in the simulation. As the noise level increases, the images reconstructed by SART and SIRT are more robust to the noise than FBP. In the phantom experiment, noise and some stripe artifacts caused by the FBP are removed by SART and SIRT algorithms. In conclusion, the IR method used in CT is applicable in MAE-CT, and it performs better than FBP, which indicates that the state-of-the-art achievements in the CT algorithm can also be adopted for the MAE-CT reconstruction in the future.
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Lin H, Chen Y, Xie S, Yu M, Deng D, Sun T, Hu Y, Chen M, Chen S, Chen X. A Dual-modal Imaging Method Combining Ultrasound and Electromagnetism for Simultaneous Measurement of Tissue Elasticity and Electrical Conductivity. IEEE Trans Biomed Eng 2022; 69:2499-2511. [PMID: 35119996 DOI: 10.1109/tbme.2022.3148120] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The mechanical and electrical properties of soft tissues are relative to soft tissues' pathological state. Modern medical imaging devices have shown a trend to multi-modal imaging, which will provide complementary functional information to improve the accuracy of disease diagnosis. However, no method or system can simultaneously measure the mechanical and electrical properties of the soft tissue. In this study, we proposed a novel dual-modal imaging method integrated by shear wave elasticity imaging (SWEI) and Magneto-acousto-electrical tomography (MAET) to measure soft tissue's elasticity and conductivity simultaneously. A dual-modal imaging system based on a linear array transducer is built, and the imaging performances of MAET and SWEI were respectively evaluated by phantoms experiment and \textit{in vitro} experiment. Conductivity phantom experiments show that the MAET in this dual-modal system can image conductivity gradient as low as 0.4 S/m. The phantom experiments show that the reconstructed 2-D elasticity maps of the phantoms with inclusions with a diameter larger than 5 mm are relatively accurate. \textit{In vitro} experiments show that the elasticity parameter can significantly distinguish the changes in tissue before and after heating. This study first proposes a method that can simultaneously obtain tissue elasticity and electrical conductivity to the best of our knowledge. Although this paper just carried out the proof of concept experiments of the new method, it demonstrates great potential for disease diagnosis in the future.
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Sun T, Hao P, Chin CT, Deng D, Chen T, Chen Y, Chen M, Lin H, Lu M, Gao Y, Chen S, Chang C, Chen X. Rapid rotational magneto-acousto-electrical tomography with filtered back-projection algorithm based on plane waves. Phys Med Biol 2021; 66. [PMID: 33725674 DOI: 10.1088/1361-6560/abef43] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/16/2021] [Indexed: 11/12/2022]
Abstract
Magneto-acousto-electrical tomography (MAET) is designed to produce conductivity images with high spatial resolution for a conducting object. In a previous study, for an irregular conductor, transverse scanning and rotational methods with a focus transducer were combined to collect complete electrical information. This kind of method, however, is time-consuming because of the transverse scanning procedure. In this study, we proposed a novel imaging method based on plane ultrasound waves and a new aspect of projection in rotational MAET. In the proposed method, we achieved the projection in each rotation angle by using plane waves rather than mechanical scanning of the focus waves along the transverse direction. Thus, the imaging time was significantly saved. To verify the proposed method, we derived a measurement formula containing a lateral integration, which built the relationship between the measurement formula and the projection under each rotation angle. Next, we constructed two different numerical models to compute magneto-acousto-electrical signals by using a finite element method and reconstructed the corresponding conductivity parameter images based on a filtered back-projection algorithm. Then, simulated signals under different signal-to-ratios (6, 20, 40, and 60 dB) were generated to test the performance of the proposed algorithm. To improve the image quality, we further analysed the influence of the filters and the frequency scaling factors embedded in the filtered back-projection algorithm. Moreover, we computed the L2norm of the error in case of different frequency scaling factors and measurement noises. Finally, we conducted a phantom experiment with a 64-element linear phased array transducer (center frequency of 2.7 MHz) and reconstructed the conductivity parameter images of the circular phantom with an elliptical hole. The experimental results demonstrated the feasibility and time-efficiency of the proposed rapid rotational MAET.
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Affiliation(s)
- Tong Sun
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Penghui Hao
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Chien Ting Chin
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
| | - Dingqian Deng
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Tiemei Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Yi Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Mian Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
| | - Haoming Lin
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
| | - Minhua Lu
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
| | - Yi Gao
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
| | - Siping Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
| | - Chunqi Chang
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
| | - Xin Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen 518060, People's Republic of China.,Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen 518060, People's Republic of China.,National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen 518060, People's Republic of China
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