基于有限元分析的CT修正胸腔建模与感生磁场计算的研究
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摘要
磁探测电阻抗成像(magnetic detection electrical impedance tomography,MDEIT)通过体表电极向成像体注入激励电流,利用外部空间磁场分布数据重建成像体内部电导率分布。MDEIT技术应用于肺部肿瘤的动态检测,实现更加贴近实际的仿真计算;应用图像分割在临床CT图像获取胸腔内部结构先验信息,进而构建正常人与肺部肿瘤患者胸腔的三维模型,应用有限元分析分别计算胸腔外部磁场分布,并对其进行特征分析。正常人与肺部肿瘤患者胸腔周围的磁感应强度在空间分布上存在差异,两者对比结果显示,患者比正常人高出10.52%。外部磁感应强度的异常一定程度上反应了胸腔内组织的病理变化,为MDEIT在肺癌检测中的应用提供合理参考。
Magnetic detection electrical impedance tomography(MDEIT) uses boundary magnetic field to reconstruct conductivity distribution inside human body,magnetic field is induced by excitation current injected to the object through surface electrodes. To achieve the dynamic detection of lung tumor using MDEIT,the computed tomography(CT) images were processed by image segmentation to obtain the priori information to construct the three-dimensional thoracic models. And then,external magnetic field were calculated basing on the finite element analysis(FEA); the difference existed in the distribution of magnetic flux density between patient and normal people. Furthermore,the magnetic flux density of patient were 10. 52% greater than that of the normal people. External magnetic flux density reflects the pathological change in the tissues of the thoracic cavity,which can provide reasonable reference to the application of the MDEIT in lung cancer detection.
Magnetic detection electrical impedance tomography(MDEIT) uses boundary magnetic field to reconstruct conductivity distribution inside human body,magnetic field is induced by excitation current injected to the object through surface electrodes. To achieve the dynamic detection of lung tumor using MDEIT,the computed tomography(CT) images were processed by image segmentation to obtain the priori information to construct the three-dimensional thoracic models. And then,external magnetic field were calculated basing on the finite element analysis(FEA); the difference existed in the distribution of magnetic flux density between patient and normal people. Furthermore,the magnetic flux density of patient were 10. 52% greater than that of the normal people. External magnetic flux density reflects the pathological change in the tissues of the thoracic cavity,which can provide reasonable reference to the application of the MDEIT in lung cancer detection.
引文
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[2]Ireland R H.Anatomically constrained image reconstruction applied to emission computed tomography&magnetic impedance tomography[D].University of Sheffield,2002.
[3]Brown B H.Electrical impedance tomography(EIT):a review[J].Journal of Medical Engineering&Technology,2003,27(3):97-108.
[4]Ahlfors S,Hmonienmi R.Magnetic imaging of conductivity[C]//14th Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society,Paris,France,1992:1717-1718.
[5]Tozer J C,Ireland R H,Barber D C,et al.Magnetic impedance tomography[J].Annals of the New York Academy of Sciences,2010,873(1):353-359.
[6]Ireland R H,Tozer J C,Barker A T,et al.Towards mangetic detection electrical impedance tomography:data acquisition and image reconsideration of current density in phantoms and in vivo[J].Physio Meas,2004,25(3):775-796.
[7]Lin L,Hao L L,Chen R J,et al.Magnetic dtection electrical impedance tomography and its application in three dimensional localization of the meridian[J].Chinese Journal of Medical Physics,2010.
[8]Hao L,Li G,Lin L.Optimization of measurement arrangements for magnetic detection electrical impedance tomography[J].IEEE Transactions on Biomedical Engineering,2014,61(2):444-452.
[9]Li G,Hao L,Chen R,et al.A new electrode mode for magnetic detection electrical Impedance tomography:computer simulation study[J].IEEE Transactions on Magnetics,2012,48(10):2543-2550.
[10]Hao L,Li G,Xu L.Magnetic detection electrical impedance tomography with total variation regularization[J].Bio-medical Materials and Engineering,2014,24(6):2857-2864.
[11]Costa,Eduardo L V,Amato,et al.Electrical impedance tomography in critically ill patients[J].Clin Pulm Med,2013,20(20):178-186.
[12]Suchomel J,Sobota V.A model of end-expiratory lung impedance-pendency on total extra cellular body water[C]//XIV Conference on Electrical Impedance Tomography.Heilbad Heiligenstadt,Germany:IOP Publishing,2013:1-4.
[13]Armato S G,Mclennan G,Bidaut L,et al.The lung image database consortium(LIDC)and image database resource initiative(IDRI):a completed reference database of lung nodules on CT scans[J].Medical Physics,2012,38(2):915-931.
[14]Dehghani H,Barber D C,Basarab-Horwath I.Incorporating a priori anatomical information into image reconstruction in electrical impedance tomography[J].Physiological Measurement,1999,20(1):87-102.
[15]Faes T J,Ha V D M,de Munck J C,et al.The electric resistivity of human tissues(100 Hz-10 MHz):a meta-analysis of review studies[J].Physiological Measurement,1999,20(4):R1.
[16]徐桂芝.生物医学电阻抗成像技术[M].机械工业出版社,2010.