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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.


Average resistivity changes compared between sitting and supine position in the selected areas as shown in Fig. (1) for the upper, middle and lower electrode positions with 0.5 (a), 1.0 (b) and 1.5 liters (c) of air inspired. The standard deviation is for six subjects. RL: right lung, LL: left lung, TL: total lung.
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Figure 3: Average resistivity changes compared between sitting and supine position in the selected areas as shown in Fig. (1) for the upper, middle and lower electrode positions with 0.5 (a), 1.0 (b) and 1.5 liters (c) of air inspired. The standard deviation is for six subjects. RL: right lung, LL: left lung, TL: total lung.

Mentions: The average percentage changes in resistivity comparing sitting and supine positions in the five chosen areas are shown in Fig. (3) for 0.5, 1.0 and 1.5 liter of air inspired at the upper, middle and lower electrode planes. The typical average resistivity change for the entire right, left and total lung regions is approximately 5% to 7% with 0.5 liter of inspiration, 7% to 9% with 1.0 liter of inspiration and 8% to 10% with 1.5 liter of inspiration. While for 8x8 pixel regions, the average resistivity changes show more variability, ranging from 2% to 6% with 0.5 liter of inspiration, 5% to 12% with 1.0 liter of inspiration and 7% to 16% with 1.5 liter of inspiration.


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)

Average resistivity changes compared between sitting and supine position in the selected areas as shown in Fig. (1) for the upper, middle and lower electrode positions with 0.5 (a), 1.0 (b) and 1.5 liters (c) of air inspired. The standard deviation is for six subjects. RL: right lung, LL: left lung, TL: total lung.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Average resistivity changes compared between sitting and supine position in the selected areas as shown in Fig. (1) for the upper, middle and lower electrode positions with 0.5 (a), 1.0 (b) and 1.5 liters (c) of air inspired. The standard deviation is for six subjects. RL: right lung, LL: left lung, TL: total lung.
Mentions: The average percentage changes in resistivity comparing sitting and supine positions in the five chosen areas are shown in Fig. (3) for 0.5, 1.0 and 1.5 liter of air inspired at the upper, middle and lower electrode planes. The typical average resistivity change for the entire right, left and total lung regions is approximately 5% to 7% with 0.5 liter of inspiration, 7% to 9% with 1.0 liter of inspiration and 8% to 10% with 1.5 liter of inspiration. While for 8x8 pixel regions, the average resistivity changes show more variability, ranging from 2% to 6% with 0.5 liter of inspiration, 5% to 12% with 1.0 liter of inspiration and 7% to 16% with 1.5 liter of inspiration.

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.