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Human CT Measurements of Structure/Electrode Position Changes During Respiration with Electrical Impedance Tomography
- Source :
- The Open Biomedical Engineering Journal
- Publication Year :
- 2013
- Publisher :
- Bentham Open, 2013.
-
Abstract
- For pulmonary applications of Electrical Impedance Tomography (EIT) systems, the electrodes are placed around the chest in a 2D ring, and the images are reconstructed based on the assumptions that the object is rigid and the measured resistivity change in EIT images is only caused by the actual resistivity change of tissue. Structural changes are rarely considered. Previous studies have shown that structural changes which result in tissue/organ and electrode position changes tend to introduce artefacts to EIT images of the thorax. Since EIT reconstruction is an ill-posed inverse problem, any small inaccurate assumptions of object may cause large artefacts in reconstructed images. Accurate information on structure/electrode position changes is a need to understand factors contributing to the measured resistivity changes and to improve EIT reconstruction algorithm. Our previous study using MRI technique showed that chest expansion leads to electrode and tissue/organ movements but not significant as proposed. The accuracy of the measurements by MRI may be limited by its relatively low temporal and spatial resolution. In this study, structure/electrode position changes during respiration cycle in patients who underwent chest CT scans are further investigated. For each patient, sixteen fiduciary markers are equally spaced around the surface, the same as the electrode placement for EIT measurements. A CT scanner with respiration-gated ability is used to acquire images of the thorax. CT thoracic images are retrospectively reconstructed corresponding temporally to specific time periods within respiration cycle (from 0% to 90%, every 10%). The average chest expansions are 2 mm in anterior-posterior and -1.6 mm in lateral directions. Inside tissue/organ move down 9.0±2.5 mm with inspiration of tidal volume (0.54±0.14 liters), ranging from 6 mm to 12 mm. During normal quiet respiration, electrode position changes are smaller than expected. No general patterns of electrode position changes are observed. The results in this study provide guidelines for accommodating the motion that may introduce artefacts to EIT images.
- Subjects :
- Thorax
medicine.medical_specialty
Scanner
Materials science
organ movement
Biomedical Engineering
Medicine (miscellaneous)
Bioengineering
Article
CT
Position (vector)
medicine
Image resolution
Electrical impedance tomography
Electrical Impedance Tomography
EIT
Respiration
electrode position change
Ranging
Reconstruction algorithm
computed tomography
Surgery
chest expansion
Electrode
sense organs
Biomedical engineering
Subjects
Details
- Language :
- English
- ISSN :
- 18741207
- Volume :
- 7
- Database :
- OpenAIRE
- Journal :
- The Open Biomedical Engineering Journal
- Accession number :
- edsair.doi.dedup.....52f397aa2b7a145c7ad30062784b80aa