磁热声成像的实验研究
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摘要
磁热声成像(MMTAI)是一种新型的人体疾病早期检测电阻抗成像技术,融合了传统电阻抗成像高对比度和超声成像高分辨率的优势。为了验证磁热声成像针对生物组织的可行性,研究了磁热声成像的原理,并搭建了相应的实验系统。研究结果表明:将低电导率目标体置于μs级脉冲宽度的脉冲磁场中,会在目标体内产生涡流,目标体吸收焦耳热后瞬时膨胀并发出声信号,声信号含有目标体的电导率信息;利用电磁场与声场理论所推导的目标体声源计算式反映了声源与电导率之间的关系;对磁-热-声多场耦合作用下产生的热声信号进行检测和分析,再利用时间反演法重建声源分布;将含质量分数10%氯化钠的凝胶仿体模型置于μs级脉冲宽度的脉冲磁场中,采用中心频率为1 MHz的超声换能器采集超声信号,信号被放大60 d B后的峰峰值约为4 m V,利用旋转凝胶仿体采集的100组信号所重建的热声图像能反映低电导率凝胶仿体的电导率分布。此实验验证了该方法用于低电导率介质成像的可行性,为该方法用于生物组织成像的研究提供了依据。
Magnetically mediated thermoacoustic imaging(MMTAI) is a novel electrical impedance tomography for early detection of human diseases, which combines the advantages of high contrast of the classic electrical impedance tomography with the high spatial resolution of sonography. In order to verify the feasibility of magnetically mediated thermoacoustic imaging for biological tissues, the principle of magnetically mediated thermoacoustic imaging was studied and the experimental system was established. The study results demonstrate that when a microsecond width pulse magnetic field is applied to an object, the object absorbs Joule heating and causes heat expansion due to the effect of induced eddy current in the object. The ultrasonic signals are sent out, which involves the conductivity information of the object. Based on the theories of electromagnetic field and acoustic field, the calculation formula of acoustic source was deduced, which revealed the relationship between acoustic source and conductivity of the object. Thermoacoustic signals produced under the action of the magneto-thermos-acoustic multi fields were detected and analyzed to reconstruct the acoustic source distribution by time reversal algorithm. The gel phantom model with the mass fraction of 10% sodium chloride was placed in the microsecond width pulse magnetic field, which caused thermoacoustic signals. After the signals were detected by ultrasonic transducer with the center frequency of 1 MHz and amplified by 60 d B, the peak value of the signals was about 4 m V. The reconstructed thermoacoustic image using 100 sets of data, which were acquired by rotating the gel phantom, could reflect the conductivity distribution of the low conductivity gel phantom. The experiments verifiy that the method for low conductivity medium imaging possesses the feasibility, and provides a basis for its potential applications to imaging in biological tissues.
Magnetically mediated thermoacoustic imaging(MMTAI) is a novel electrical impedance tomography for early detection of human diseases, which combines the advantages of high contrast of the classic electrical impedance tomography with the high spatial resolution of sonography. In order to verify the feasibility of magnetically mediated thermoacoustic imaging for biological tissues, the principle of magnetically mediated thermoacoustic imaging was studied and the experimental system was established. The study results demonstrate that when a microsecond width pulse magnetic field is applied to an object, the object absorbs Joule heating and causes heat expansion due to the effect of induced eddy current in the object. The ultrasonic signals are sent out, which involves the conductivity information of the object. Based on the theories of electromagnetic field and acoustic field, the calculation formula of acoustic source was deduced, which revealed the relationship between acoustic source and conductivity of the object. Thermoacoustic signals produced under the action of the magneto-thermos-acoustic multi fields were detected and analyzed to reconstruct the acoustic source distribution by time reversal algorithm. The gel phantom model with the mass fraction of 10% sodium chloride was placed in the microsecond width pulse magnetic field, which caused thermoacoustic signals. After the signals were detected by ultrasonic transducer with the center frequency of 1 MHz and amplified by 60 d B, the peak value of the signals was about 4 m V. The reconstructed thermoacoustic image using 100 sets of data, which were acquired by rotating the gel phantom, could reflect the conductivity distribution of the low conductivity gel phantom. The experiments verifiy that the method for low conductivity medium imaging possesses the feasibility, and provides a basis for its potential applications to imaging in biological tissues.
引文
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[19]FENG X,GAO F,ZHENG Y.Magnetically mediated thermoacoustic imaging toward deeper penetration[J].Applied Physics Letters,2013,103(8):083704-083707.
[20]FENG X,GAO F,ZHENG Y.Magnetically mediated thermoacoustic imaging[C]∥Proceedings of the Conference on Photons Plus Ultra-sound:Imaging and Sensing.California,USA:[s.n.],2014:894343.
[21]FENG X,GAO F,ZHENG Y.Modulatable magnetically mediated thermoacoustic imaging with magnetic nanoparticals[J].Applied Physics Letters,2015,106(15):093705.
[22]WANG X,PANG Y,KU G,et al.Noninvasive laser-induced photoacoustic tomography for structural and functional in vivo imaging of the brain[J].Nature Biotechnology,2003,21(7):803-806.
[23]KU G,FOMAGE B D,JIN X,et al.Thermoacoustic and photoacoustic tomography of thick biological tissues toward breast imaging[J].Technology in Cancer Research and Treatment,2005,4(5):559-566.
[24]LIU Z,LIU L,XU Y,et al.Transcranial thermoacoustic tomography:a comparison of two imaging algorithms[J].IEEE Transactions on Medical Imaging,2012,32(2):289-294.
[25]WANG X.Thermoacoustic applications in breast cancer detection and communications[D].Tucson,USA:University of Arizona,2014.
[26]李江涛,郑敏军,曹辉.经颅磁刺激技术的研究进展[J].高电压技术,2016,42(4):1168-1178.LI Jiangtao,ZHENG Minjun,CAO Hui.Research progress in transcranial magnetic stimulation technology[J].High Voltage Engineering,2016,42(4):1168-1178.
[27]MALLIDI S,LUKE G P,EMELIANOV S.Photoacoustic imaging in cancer detection,diagnosis and treatment guidance[J].Trends in Biotechnology,2011,29(5):213-221.
[28]BEARD P.Biomedical photoacoustic imaging[J].Interface Focus,2011,1(4):602-631.
[29]ZACKRISSON S,VEN S M W Y V D,GAMBHIR S S.Light in and sound out:emerging translational strategies foe photoacoustic imaging[J].Cancer Research,2014,74(4):979-1004.
[30]JATHOUL A P,LAUFER J,OGUNLADE O,et al.Deep on vivo photoacoustic imaging of mammalian tissues using a tyrosinase-based genetic reporter[J].Nature Photonics,2015,9(4):239-246.
[31]CAO Y,HUI J,AVEESHIK K,et al.High-sensitivity intravascular photoacoustic imaging of lipid-laden plaque with a collinear catheter design[J].Scientific Reports,2016,6:25236.
[32]MASHAL A,BOOSKE J H,HAGNESS S C.Toward contrast-enhanced microwave-induced thermoacoustic imaging of breast cancer:an experimental study of the effects of microbubbles on simple thermoacoustic targets[J].Physics in Medicine and Biology,2009,54(3):641-650.
[33]JOACHIMOWICA N,CONESSA C,HENRIKSSON T,et al.Breast phantoms for microwave imaging[J].IEEE Antennas and Wireless Propagation Letters,2014,13:1333-1336.
[34]CASE J T,GHASR M T,ZOUGHI R.Correcting mutual coupling and poor isolation for real-time 2-D microwave imaging systems[J].IEEE Transactions on Instrumentation and Measurement,2014,63(5):1310-1319.
[35]WANG X,QIN T,WITTE R S,et al.Computational feasibility study of contrast-enhanced thermoacoustic imaging for breast cancer detection using realistic numerical breast phantoms[J].IEEE Transactions on Microwave Theory and Techniques,2015,65(5):1-13.
[36]张琴,熊正爱,周玮,等.脉冲电场对人宫颈癌Hela细胞侵袭转移能力的影响[J].中国组织工程研究,2011,15(28):5245-5248.ZHANG Qin,XIONG Zheng’ai,ZHOU Wei,et al.Pulse electric fields effect on invasion and metastasis of Hela cells in human cervical cancer[J].Chinese Journal of Tissue Engineering Research,2011,15(28):5245-5248.
[37]李成祥.不可逆电穿孔治疗肿瘤的作用机理及临床应用关键技术的研究[D].重庆:重庆大学,2011.LI Chengxiang.Studies on mechanism and key technologies for clinical application of IRE tumor treatment[D].Chongqing,China:Chongqing University,2011.
[38]曲敏,毕卓悦,唐雨萌,等.生物电磁技术应用及其相关健康风险评估对策[J].高电压技术,2015,41(8):2625-2643.QU Min,BI Zhuoyue,TANG Yumeng,et al.Application of bio-electromagnetic technique and its related health risk assessment strategy[J].High Voltage Engineering,2015,41(8):2625-2643.
[39]包家立.极低频电磁场的健康效应[J].高电压技术,2015,41(8):2550-2561.BAO Jiali.Health effects of extremely low frequency electromagnetic fields[J].High Voltage Engineering,2015,41(8):2550-2561.
[40]包家立,胡亚楠.射频电磁场的健康效应[J].高电压技术,2016,42(8):2353-2366.BAO Jiali,HU Yanan.Health effects of radio-frequency electromagnetic fields[J].High Voltage Engineering,2016,42(8):2353-2366.
[41]GUO L,JIANG W C,LIU G Q,et al.Development of the pulse magnetic field excitation system in magnetoacoustic tomography[C]∥IEEE International Conference on Electron Devices and Solid-State Circuits.Singapore:IEEE,2015:329-332.
[42]GUO L,LIU G,YANG Y.Difference frequency magnetoacoustic tomography without static magnetic field[J].Applied Physics Express,2015,8(8):086601.
[2]KWON O,WOO E J,YOON J R,et al.Magnetic resonance electrical impedance tomography(MREIT):simulation study of J-substitution algorithm[J].IEEE Transactions on Biomedical Engineering,2002,49(2):160-167.
[3]LI X,XU Y,HE B.Imaging electrical impedance from acoustic measurements by means of magnetoacoustic tomography with magnetic induction(MAT-MI)[J].IEEE Transactions on Biomedical Engineering,2007,54(2):323-330.
[4]刘国强.医学电磁成像[M].北京:科学出版社,2006.LIU Guoqiang.Medical electromagnetic imaging[M].Beijing,China:Science Press,2006.
[5]闫丹丹,沈圣远,李怀明.三维脑部电阻抗成像技术研究[J].中国计量学院学报,2015,26(3):331-335.YAN Dandan,SHEN Shengyuan,LI Huaiming.Electric impedance tomography imaging study based on the differential evolution algorithm[J].Journal of China University of Metrology,2015,26(3):331-335.
[6]王浩.感应式磁声成像算法研究[D].北京:中国科学院电工研究所,2008.WANG Hao.The algorithm of magnetoacoustic tomography with magnetic induction[D].Beijing,China:Institute of Electrical Engineering,Chinese Academy of Sciences,2008.
[7]陈晶,刘国强,夏慧.基于矩阵模型的感应式磁声重建算法[J].现代科学仪器,2013(2):34-38.CHEN Jing,LIU Guoqiang,XIA Hui.Conductivity reconstruction for magnetoacoustic tomography based on the system matrix[J].Modern Scientific Instruments,2013(2):34-38.
[8]刘国强.磁声成像技术[M].北京:科学出版社,2014.LIU Guoqiang.Magnetoacoustic tomography technology[M].Beijing,China:Science Press,2014.
[9]AMMARI H,BOULMIER S,MILLIEN P.A mathematical and numerical framework for magnetoacoustic tomography with magnetic induction[J].Journal of Differential Equations,2015,259(10):5379-5405.
[10]YU K,SHAO Q,ASHKENAZI S,et al.In vivo electrical conductivity contrast imaging in a mouse model of cancer using high-frequency magnetoacoustic tomography with magnetic induction(hf MAT-MI)[J].IEEE Transactions on Medical Imaging,2016,35(10):2301-2311.
[11]LIU G Q,HUANG X,XIA H,et al.Magnetoacoustic tomography with current injection[J].Chinese Science Bulletin,2013,58(30):3600-3606.
[12]黄欣.注入电流式磁声成像的基础研究[D].北京:中国科学院大学,2013.HUANG Xin.Findamental investigationson on magnetoacoustic tomography with current injection[D].Beijing,China:University of Chinese Academy of Sciences,2013.
[13]WANG S,MA R,ZHANG S,et al.Translational-circular scanning for magneto-acoustic tomography with current injection[J].Biomedical Engineering Online,2016,15(1):1-17.
[14]雷云,丁里,任丽香,等.3.0 T MRI对颈动脉粥样硬化斑块成分分析及分型的研究[J].磁共振成像,2015,6(6):430-436.LEI Yun,DING Li,REN Lixiang,et al.Carotid atherosclerotic plaque composition analysis and classification with 3.0 T MRI[J].Chinese Journal of Magnetic Resonance Imaging,2015,6(6):430-436.
[15]SEO J K,WOO E J.Magnetic resonance electrical impedance tomography(MREIT)[J].Physiological Measurement,2008,29(10):R1-26.
[16]KRANJC M,BAJD F.Magnetic resonance electrical impedance tomography for measuring electrical conductivity during electroporation[J].Physiological Measurement,2014,35(6):985-996.
[17]闫丹丹,沈圣远,陈会.基于磁共振电阻抗成像技术的3维脑病变检测仿真[J].高电压技术,2015,41(4):1372-1376.YAN Dandan,SHEN Shengyuan,CHEN Hui.3D Brain anomaly tissues detection simulation based on magnetic resonance electrical impedance tomography[J].High Voltage Engineering,2015,41(4):1372-1376.
[18]SAJIB S Z K,JI E K,JEONG W C,et al.Reconstruction of apparent orthotropic conductivity tensor image using magnetic resonance electrical impedance tomography[J].Journal of Applied Physics,2015,117(10):104701-104711.
[19]FENG X,GAO F,ZHENG Y.Magnetically mediated thermoacoustic imaging toward deeper penetration[J].Applied Physics Letters,2013,103(8):083704-083707.
[20]FENG X,GAO F,ZHENG Y.Magnetically mediated thermoacoustic imaging[C]∥Proceedings of the Conference on Photons Plus Ultra-sound:Imaging and Sensing.California,USA:[s.n.],2014:894343.
[21]FENG X,GAO F,ZHENG Y.Modulatable magnetically mediated thermoacoustic imaging with magnetic nanoparticals[J].Applied Physics Letters,2015,106(15):093705.
[22]WANG X,PANG Y,KU G,et al.Noninvasive laser-induced photoacoustic tomography for structural and functional in vivo imaging of the brain[J].Nature Biotechnology,2003,21(7):803-806.
[23]KU G,FOMAGE B D,JIN X,et al.Thermoacoustic and photoacoustic tomography of thick biological tissues toward breast imaging[J].Technology in Cancer Research and Treatment,2005,4(5):559-566.
[24]LIU Z,LIU L,XU Y,et al.Transcranial thermoacoustic tomography:a comparison of two imaging algorithms[J].IEEE Transactions on Medical Imaging,2012,32(2):289-294.
[25]WANG X.Thermoacoustic applications in breast cancer detection and communications[D].Tucson,USA:University of Arizona,2014.
[26]李江涛,郑敏军,曹辉.经颅磁刺激技术的研究进展[J].高电压技术,2016,42(4):1168-1178.LI Jiangtao,ZHENG Minjun,CAO Hui.Research progress in transcranial magnetic stimulation technology[J].High Voltage Engineering,2016,42(4):1168-1178.
[27]MALLIDI S,LUKE G P,EMELIANOV S.Photoacoustic imaging in cancer detection,diagnosis and treatment guidance[J].Trends in Biotechnology,2011,29(5):213-221.
[28]BEARD P.Biomedical photoacoustic imaging[J].Interface Focus,2011,1(4):602-631.
[29]ZACKRISSON S,VEN S M W Y V D,GAMBHIR S S.Light in and sound out:emerging translational strategies foe photoacoustic imaging[J].Cancer Research,2014,74(4):979-1004.
[30]JATHOUL A P,LAUFER J,OGUNLADE O,et al.Deep on vivo photoacoustic imaging of mammalian tissues using a tyrosinase-based genetic reporter[J].Nature Photonics,2015,9(4):239-246.
[31]CAO Y,HUI J,AVEESHIK K,et al.High-sensitivity intravascular photoacoustic imaging of lipid-laden plaque with a collinear catheter design[J].Scientific Reports,2016,6:25236.
[32]MASHAL A,BOOSKE J H,HAGNESS S C.Toward contrast-enhanced microwave-induced thermoacoustic imaging of breast cancer:an experimental study of the effects of microbubbles on simple thermoacoustic targets[J].Physics in Medicine and Biology,2009,54(3):641-650.
[33]JOACHIMOWICA N,CONESSA C,HENRIKSSON T,et al.Breast phantoms for microwave imaging[J].IEEE Antennas and Wireless Propagation Letters,2014,13:1333-1336.
[34]CASE J T,GHASR M T,ZOUGHI R.Correcting mutual coupling and poor isolation for real-time 2-D microwave imaging systems[J].IEEE Transactions on Instrumentation and Measurement,2014,63(5):1310-1319.
[35]WANG X,QIN T,WITTE R S,et al.Computational feasibility study of contrast-enhanced thermoacoustic imaging for breast cancer detection using realistic numerical breast phantoms[J].IEEE Transactions on Microwave Theory and Techniques,2015,65(5):1-13.
[36]张琴,熊正爱,周玮,等.脉冲电场对人宫颈癌Hela细胞侵袭转移能力的影响[J].中国组织工程研究,2011,15(28):5245-5248.ZHANG Qin,XIONG Zheng’ai,ZHOU Wei,et al.Pulse electric fields effect on invasion and metastasis of Hela cells in human cervical cancer[J].Chinese Journal of Tissue Engineering Research,2011,15(28):5245-5248.
[37]李成祥.不可逆电穿孔治疗肿瘤的作用机理及临床应用关键技术的研究[D].重庆:重庆大学,2011.LI Chengxiang.Studies on mechanism and key technologies for clinical application of IRE tumor treatment[D].Chongqing,China:Chongqing University,2011.
[38]曲敏,毕卓悦,唐雨萌,等.生物电磁技术应用及其相关健康风险评估对策[J].高电压技术,2015,41(8):2625-2643.QU Min,BI Zhuoyue,TANG Yumeng,et al.Application of bio-electromagnetic technique and its related health risk assessment strategy[J].High Voltage Engineering,2015,41(8):2625-2643.
[39]包家立.极低频电磁场的健康效应[J].高电压技术,2015,41(8):2550-2561.BAO Jiali.Health effects of extremely low frequency electromagnetic fields[J].High Voltage Engineering,2015,41(8):2550-2561.
[40]包家立,胡亚楠.射频电磁场的健康效应[J].高电压技术,2016,42(8):2353-2366.BAO Jiali,HU Yanan.Health effects of radio-frequency electromagnetic fields[J].High Voltage Engineering,2016,42(8):2353-2366.
[41]GUO L,JIANG W C,LIU G Q,et al.Development of the pulse magnetic field excitation system in magnetoacoustic tomography[C]∥IEEE International Conference on Electron Devices and Solid-State Circuits.Singapore:IEEE,2015:329-332.
[42]GUO L,LIU G,YANG Y.Difference frequency magnetoacoustic tomography without static magnetic field[J].Applied Physics Express,2015,8(8):086601.
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