Fetal Imaging with Dynamic Electrical Impedance Tomography Technique

The fetal movements are the primary parameters that are clinically significant for determining the fetal growth and well-being during pregnancy. Conventional methods such as ultrasound, magnetocardiography are expensive and cannot be used for continuous monitoring. Moreover, to operate the instruments and analyze the images, they need experts. For a better healthy pregnancy outcome, an appropriate, portable, low cost, non-invasive and continuous imaging technique is essential to reconstruct the fetal movements inside abdomen during pregnancy. As an alternative method, electrical impedance tomography can be used as a continuous fetal monitoring imaging tool. This work introduces dynamic electrical impedance tomography (EIT) imaging technique to reconstruct the fetus movements inside abdomen. Dynamic EIT is a non-invasive and non-ionizing imaging modality that can estimate and reconstruct the time varying conductivity distribution of fetus inside pregnant women by injecting a small magnitude of electrical currents through the skin electrodes placed on the surface of the abdomen and measuring the resulting voltages across the electrodes. The problem of estimating the time varying fetus conductivity distribution due to fetal movement is treated as a state estimation problem and the state variables are the conductivity of finite elements that are discretized across the abdomen. Extended Kalman filtering method is used as an inverse algorithm to estimate the time varying state variables. Numerical simulations with abdomen shaped mesh and phantom studies are done to verify the feasibility of dynamic EIT system for fetus monitoring.