Figure 1 | Scientific Reports

Figure 1

From: Non-invasive pulmonary artery pressure estimation by electrical impedance tomography in a controlled hypoxemia study in healthy subjects

Figure 1

Estimation of the pulmonary PTT (as the pulse arrival time) from ECG and EIT data. After (i) EIT image reconstruction, each pixel-wise EIT time signal is (ii) high-pass filtered and summarized to one representative pulse through ECG-gated ensemble averaging, resulting in (iii) N cardio-synchronous ensemble average pulses for the N pixels of the EIT image sequence. (iv) The modulus and phase of all N ensemble average pulses is calculated and a pulmonary region of interest of M pixels is obtained by finding all pixels with significant pulsatile amplitude showing coherent phase with the average cardiac-related EIT signal. (v) For each of the M pulmonary pixels, the PTT is estimated using the maximum of its first time derivative. Finally, the global pulmonary PTT is obtained by averaging the PTT values of all M pulmonary pixels after outlier rejection using the MAD method. ECG electrocardiography, EIT electrical impedance tomography, PTT pulse transit time, MAD median absolute deviation.

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