目的:在广义有限元法和时间反演算法理论的基础上研究一种新型的算法,以重建声学非均匀介质中的声源分布。方法:通过磁声耦合理论,结合声学的基本方程研究声学非均匀同心球模型感应式磁声成像(magnetoacoustic tomography with magnetic...目的:在广义有限元法和时间反演算法理论的基础上研究一种新型的算法,以重建声学非均匀介质中的声源分布。方法:通过磁声耦合理论,结合声学的基本方程研究声学非均匀同心球模型感应式磁声成像(magnetoacoustic tomography with magnetic induction,MAT-MI)正、逆问题,提出基于广义有限元法的声学非均匀媒介波动方程求解办法,对时间反演算法进行改进,采用介质声学特征先验信息,重建声速的分布,并利用该算法解决声学非均匀媒介声源重建和电导率重建的问题。结果:所提出的算法能够准确地重建声学非均匀介质中的声源分布,在重建声源的过程中可以获得声速的分布并能够很好地对图像进行重建。结论:该算法在声学非均匀媒介的MAT-MI重建问题上具有较强的优势,可为后续更加准确地重构不同声学特性和电学特性MAT-MI图像提供必要的参考数据,同时也可将MAT-MI技术向着临床应用推进一步。展开更多
Based on the acoustic radiation theory of a dipole source, the influence of the transducer reception pattern is studied for magnetoacoustic tomography with magnetic induction（MAT-MI）. Numerical studies are conducted...Based on the acoustic radiation theory of a dipole source, the influence of the transducer reception pattern is studied for magnetoacoustic tomography with magnetic induction（MAT-MI）. Numerical studies are conducted to simulate acoustic pressures, waveforms, and reconstructed images with unidirectional, omnidirectional, and strong directional transducers.With the analyses of equivalent and projection sources, the influences of the model dimension and the layer effect are qualitatively analyzed to evaluate the performance of MAT-MI. Three-dimensional simulation studies show that the strong directional transducer with a large radius can reduce the influences of equivalent sources, projection sources, and the layer effect effectively, resulting in enhanced pressure and improved image contrast, which is beneficial for boundary pressure extraction in conductivity reconstruction. The reconstructed conductivity contrast images present the conductivity boundaries as stripes with different contrasts and polarities, representing the values and directions of the conductivity changes of the scanned layer. The favorable results provide solid evidence for transducer selection and suggest potential practical applications of MAT-MI in biomedical imaging.展开更多
Magnetoacoustic tomography with magnetic induction(MAT-MI),as a new kind of in-vivo imaging method,has potential application value in interstitial fluid research.In this paper,we propose the application of MAT-MI with...Magnetoacoustic tomography with magnetic induction(MAT-MI),as a new kind of in-vivo imaging method,has potential application value in interstitial fluid research.In this paper,we propose the application of MAT-MI with liquid metal serving as a tracer of the interstitial structure to study its fluid behavior,and use it to implement the positional imaging of the spatial distribution of liquid metal.Owing to the particularity of liquid metal magnetoacoustic pressure(MAP)signals,we propose an envelope analysis method to extract the rising edge of the amplitude envelope of the detected waveform as effective position data.And for the first time,we propose the method of superpositing pixel matrix to achieve the position imaging of liquid metal.Finally,the positional imaging of the liquid metal sample embedded in the gel is achieved to have relatively accurate results.This study provides a method of effectively extracting data and implementing the position imaging for liquid metal in the interstitial structure in the frame of MAT-MI.展开更多
文摘目的:在广义有限元法和时间反演算法理论的基础上研究一种新型的算法,以重建声学非均匀介质中的声源分布。方法:通过磁声耦合理论,结合声学的基本方程研究声学非均匀同心球模型感应式磁声成像(magnetoacoustic tomography with magnetic induction,MAT-MI)正、逆问题,提出基于广义有限元法的声学非均匀媒介波动方程求解办法,对时间反演算法进行改进,采用介质声学特征先验信息,重建声速的分布,并利用该算法解决声学非均匀媒介声源重建和电导率重建的问题。结果:所提出的算法能够准确地重建声学非均匀介质中的声源分布,在重建声源的过程中可以获得声速的分布并能够很好地对图像进行重建。结论:该算法在声学非均匀媒介的MAT-MI重建问题上具有较强的优势,可为后续更加准确地重构不同声学特性和电学特性MAT-MI图像提供必要的参考数据,同时也可将MAT-MI技术向着临床应用推进一步。
基金Project supported by the National Basic Research Program of China(Grant No.2011CB707900)the National Natural Science Foundation of China(Grant Nos 11274176 and 11474166)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Based on the acoustic radiation theory of a dipole source, the influence of the transducer reception pattern is studied for magnetoacoustic tomography with magnetic induction（MAT-MI）. Numerical studies are conducted to simulate acoustic pressures, waveforms, and reconstructed images with unidirectional, omnidirectional, and strong directional transducers.With the analyses of equivalent and projection sources, the influences of the model dimension and the layer effect are qualitatively analyzed to evaluate the performance of MAT-MI. Three-dimensional simulation studies show that the strong directional transducer with a large radius can reduce the influences of equivalent sources, projection sources, and the layer effect effectively, resulting in enhanced pressure and improved image contrast, which is beneficial for boundary pressure extraction in conductivity reconstruction. The reconstructed conductivity contrast images present the conductivity boundaries as stripes with different contrasts and polarities, representing the values and directions of the conductivity changes of the scanned layer. The favorable results provide solid evidence for transducer selection and suggest potential practical applications of MAT-MI in biomedical imaging.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61771448,61427806,and 51937010)the National Key Research and Development Program of China(Grant No.2018YFC0115200)the Natural Science Fund from the Chinese Academy of Sciences(Grant Nos.ZDKYYQ20190002 and YJKYYQ20190005)。
文摘Magnetoacoustic tomography with magnetic induction(MAT-MI),as a new kind of in-vivo imaging method,has potential application value in interstitial fluid research.In this paper,we propose the application of MAT-MI with liquid metal serving as a tracer of the interstitial structure to study its fluid behavior,and use it to implement the positional imaging of the spatial distribution of liquid metal.Owing to the particularity of liquid metal magnetoacoustic pressure(MAP)signals,we propose an envelope analysis method to extract the rising edge of the amplitude envelope of the detected waveform as effective position data.And for the first time,we propose the method of superpositing pixel matrix to achieve the position imaging of liquid metal.Finally,the positional imaging of the liquid metal sample embedded in the gel is achieved to have relatively accurate results.This study provides a method of effectively extracting data and implementing the position imaging for liquid metal in the interstitial structure in the frame of MAT-MI.
