In vivo measurements for construction an anatomical thoracic atlas for electrical impedance tomography (EIT): Methods for EIT regularizations

In vivo measurements were acquired to develop the anatomical atlas of resistivity based on electrical properties of biological tissues. These data serve as the regularization for EIT algorithm. The measurements were carried out at 125 kHz on biological swine tissues. Plunge electrodes in four-terminal configuration and a computer-automated measurement system were used to acquire admitivity data. Measurements were taken on myocardial muscle (three different positions on epicardial surface), pectoral and intercostals muscles, adipose tissue, costal cartilage and lungs (cranial lobe, middle lobe and caudal lobe). Admitivity temporal variations synchronized with perfusion and ventilation rates were observed. Increased PEEP lead to increased time averaged admitivity in lung tissues. The collected data were used to increased image resolution on EIT.