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Variability in EIT Images of Lung Ventilation as a Function of Electrode Planes and Body Positions.

Zhang J, Patterson R - Open Biomed Eng J (2014)

Bottom Line: There was no significant difference (p>0.05) between supine and sitting.The two 8x8 regions show a larger inter individual variability (coefficient of variation, CV, is from 30% to 382%) compared to the entire left, entire right and total lung (CV is from 11% to 51%).The results for the global regions are more consistent.

View Article: PubMed Central - PubMed

Affiliation: Division of Medical Physics, Department of Radiology, University of Kentucky, Lexington, KY 40536, USA.

ABSTRACT
This study is aimed at investigating the variability in resistivity changes in the lung region as a function of air volume, electrode plane and body position. Six normal subjects (33.8 ± 4.7 years, range from 26 to 37 years) were studied using the Sheffield Electrical Impedance Tomography (EIT) portable system. Three transverse planes at the level of second intercostal space, the level of the xiphisternal joint, and midway between upper and lower locations were chosen for measurements. For each plane, sixteen electrodes were uniformly positioned around the thorax. Data were collected with the breath held at end expiration and after inspiring 0.5, 1.0, or 1.5 liters of air from end expiration, with the subject in both the supine and sitting position. The average resistivity change in five regions, two 8x8 pixel local regions in the right lung, entire right, entire left and total lung regions, were calculated. The results show the resistivity change averaged over electrode positions and subject positions was 7-9% per liter of air, with a slightly larger resistivity change of 10 % per liter air in the lower electrode plane. There was no significant difference (p>0.05) between supine and sitting. The two 8x8 regions show a larger inter individual variability (coefficient of variation, CV, is from 30% to 382%) compared to the entire left, entire right and total lung (CV is from 11% to 51%). The results for the global regions are more consistent. The large inter individual variability appears to be a problem for clinical applications of EIT, such as regional ventilation. The variability may be mitigated by choosing appropriate electrode plane, body position and region of interest for the analysis.

No MeSH data available.


Comparison between the results with the same reference used for all measurement within one plane in one subject and those with individual references used for each of the three other volumes. The standard deviation is for the ten trials in one subject.
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Figure 2: Comparison between the results with the same reference used for all measurement within one plane in one subject and those with individual references used for each of the three other volumes. The standard deviation is for the ten trials in one subject.

Mentions: The experiment was repeated 10 times in one subject without removing the electrodes over a time period of two hours to determine the reproducibility. Data were analyzed with two different reference frames. The first method used the same reference for all three other air volumes in the lung for each electrode plane. The second method used an individual reference obtained at the start of inspiration for each of the three volumes. As shown in Fig. (2), there was no significant difference (p>0.05). In the study, the same reference was used to reconstruct the EIT images.


Variability in EIT Images of Lung Ventilation as a Function of Electrode Planes and Body Positions.

Zhang J, Patterson R - Open Biomed Eng J (2014)

Comparison between the results with the same reference used for all measurement within one plane in one subject and those with individual references used for each of the three other volumes. The standard deviation is for the ten trials in one subject.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126188&req=5

Figure 2: Comparison between the results with the same reference used for all measurement within one plane in one subject and those with individual references used for each of the three other volumes. The standard deviation is for the ten trials in one subject.
Mentions: The experiment was repeated 10 times in one subject without removing the electrodes over a time period of two hours to determine the reproducibility. Data were analyzed with two different reference frames. The first method used the same reference for all three other air volumes in the lung for each electrode plane. The second method used an individual reference obtained at the start of inspiration for each of the three volumes. As shown in Fig. (2), there was no significant difference (p>0.05). In the study, the same reference was used to reconstruct the EIT images.

Bottom Line: There was no significant difference (p>0.05) between supine and sitting.The two 8x8 regions show a larger inter individual variability (coefficient of variation, CV, is from 30% to 382%) compared to the entire left, entire right and total lung (CV is from 11% to 51%).The results for the global regions are more consistent.

View Article: PubMed Central - PubMed

Affiliation: Division of Medical Physics, Department of Radiology, University of Kentucky, Lexington, KY 40536, USA.

ABSTRACT
This study is aimed at investigating the variability in resistivity changes in the lung region as a function of air volume, electrode plane and body position. Six normal subjects (33.8 ± 4.7 years, range from 26 to 37 years) were studied using the Sheffield Electrical Impedance Tomography (EIT) portable system. Three transverse planes at the level of second intercostal space, the level of the xiphisternal joint, and midway between upper and lower locations were chosen for measurements. For each plane, sixteen electrodes were uniformly positioned around the thorax. Data were collected with the breath held at end expiration and after inspiring 0.5, 1.0, or 1.5 liters of air from end expiration, with the subject in both the supine and sitting position. The average resistivity change in five regions, two 8x8 pixel local regions in the right lung, entire right, entire left and total lung regions, were calculated. The results show the resistivity change averaged over electrode positions and subject positions was 7-9% per liter of air, with a slightly larger resistivity change of 10 % per liter air in the lower electrode plane. There was no significant difference (p>0.05) between supine and sitting. The two 8x8 regions show a larger inter individual variability (coefficient of variation, CV, is from 30% to 382%) compared to the entire left, entire right and total lung (CV is from 11% to 51%). The results for the global regions are more consistent. The large inter individual variability appears to be a problem for clinical applications of EIT, such as regional ventilation. The variability may be mitigated by choosing appropriate electrode plane, body position and region of interest for the analysis.

No MeSH data available.