A Study Of Lung Three-dimensional Electrical Impedance Imaging Method Incorporating Respiratory Prior Features

Lung Electrical Impedance Tomography(Electrical Impedance Tomography,EIT)belongs to a kind of new imaging technology,it gives safe exciting current and measures the voltage change of corresponding electrodes through a series of electrodes placed on the human body chest on the surface of the skin,and the distribution of electrical properties of the human lungs is reconstructed by the image reconstruction algorithm.At present,it has been applied to dynamic monitoring of lung function,which can effectively detect and diagnose atelectasis and local dilatation of lung.Current image reconstruction for lungs is focused on 2D plane.When we are breathing,the air is going in or out through the lungs.It makes the lungs in a state of contraction or expansion.As a result,the capacity of lungs is changed.The shape and location of lungs are also varied accordingly.The information of lungs movement is the key to the accurate localization of the lesion and the accurate diagnosis of lungs disease.However,existing lung EIT work has not explored the respiratory status of the lungs.Therefore,the 3D lung electrical impedance imaging algorithm is optimized,the changes of the lung geometric structure during breathing are fully considered,and the 3D lung electrical impedance imaging under different breathing states are realized in this paper.Meanwhile,the movement state of the lungs during breathing is detected based on the reconstruction results.The main contents of this paper are as follows:1.The lung CT images in the end-expiratory state and the end-inspiratory state are extracted as the prior information of human body geometric structure to construct the EIT 3D positive problem models of the chests under the two breathing states.The number,shape of electrodes and spacing of electrode layers are analyzed and discussed to optimize the electrodes models under the two breathing states.2.A lung EIT image reconstruction algorithm based on Bregman's Modified Total Variation(MTV)is proposed.The parameters of the MTV algorithm are discussed and analyzed based on the end-expiratory and end-inspiratory models of the lungs in this paper.The lungs EIT is simulated and verified by experiment based on MTV algorithm.Experimental results show that the MTV algorithm has excellent performance in lungs 3D EIT imaging.3.A respiratory movement detection method is proposed.Aiming at changes of lungs ventilation in respiratory movement and position deviation of lungs.The position of lungs and offset distance between end-expiratory and end-inspiratory states are calculated based on the 3D reconstruction results.As a result,the respiratory movement could be analyzed through EIT reconstruction.