Regional lung perfusion as determined by electrical impedance tomography in comparison with electron beam CT imaging

Abstract

The aim of the experiments was to check the feasibility of pulmonary perfusion imaging by functional electrical impedance tomography (EIT) and to compare the EIT findings with electron beam computed tomography (EBCT) scans. In three pigs, a Swan-Ganz catheter was positioned in a pulmonary artery branch and hypertonic saline solution or a radiographic contrast agent were administered as boli through the distal or proximal openings of the catheter. During the administration through the proximal opening, the balloon at the tip of the catheter was either deflated or inflated. The latter case represented a perfusion defect. The series of EIT scans of the momentary distribution of electrical impedance within the chest were obtained during each saline bolus administration at a rate of 13/s. EBCT scans were acquired at a rate of 3.3/s during bolus administrations of the radiopaque contrast material under the same steady-state conditions. The EIT data were used to generate local time-impedance curves and functional EIT images showing the perfusion of a small lung region, both lungs with a perfusion defect and complete both lungs during bolus administration through the distal and proximal catheter opening with an inflated or deflated balloon, respectively. The results indicate that EIT imaging of lung perfusion is feasible when an electrical impedance contrast agent is used.

In-vitro evaluation of contrast media for assessment of regional perfusion distribution by Electrical Impedance Tomography (EIT)

“…In 1992 Brown et al [2] applied an isotonic 0.9% NaCl solution. About 10 years later the first usage of a hypertonic 1molar (5.8%) NaCl solution in animals was published [3]. This approach was later on used in animal experiments in view of estimation of local ventilation and perfusion distribution (V˙/Q˙ ratio) [4].…”

Imaging cardiac activity by the D-bar method for electrical impedance tomography

“…The ACT3 system (Edic et al 1995) has also been used extensively to image ventilation and perfusion in human subjects. Cross-sectional images of cardiac activity using the ACT3 system (Edic et al 1995) and the NOSER reconstruction algorithm (Cheney et al 1990) can be found in Cheney et al 1999. Other investigations of the feasibility and reproducibility of using EIT to image cardiac activity include Vonk Noordegraaf et al (1996,1997,1998), Hoetink et al 2002, Mueller et al 2001, Smit et al 2003, Frerichs et al 2002 The reader is referred to Borcea (2002) or Mueller and Siltanen (2003) for a discussion of existing reconstruction algorithms for EIT.…”

Breath detection using short-time Fourier transform analysis in electrical impedance tomography

“…STFT benefits from the high temporal resolution provided by EIT and is capable of giving stable and robust time-averaged respiratory rate estimates and hence a reliable apnea alarm. In this way, there is no need for holding the breath like previous conventional methods performing the measurements [5,11]. The STFT is also simple to implement and benefits from the high computational efficiency of the Fast Fourier Transform (FFT) algorithm.…”