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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.


Image (a) shows the automatically selected right lung (outlined in red), left lung and total lung image with a threshold of 3%. Image (b) shows the two local regions in the right lung (8x8 pixels), labeled 1 and 2. The center of area 1 lies in the middle of the left half of image b. Area 2 is area 1 repositioned 45 degrees counter clockwise. The resistivity changes in these two regions are the mean of all the pixels. R: right, L: left, P: posterior, A: anterior.
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Figure 1: Image (a) shows the automatically selected right lung (outlined in red), left lung and total lung image with a threshold of 3%. Image (b) shows the two local regions in the right lung (8x8 pixels), labeled 1 and 2. The center of area 1 lies in the middle of the left half of image b. Area 2 is area 1 repositioned 45 degrees counter clockwise. The resistivity changes in these two regions are the mean of all the pixels. R: right, L: left, P: posterior, A: anterior.

Mentions: Resistivity changes were calculated for two local regions in the right lung (8x8 pixels) [10, 11] and for the right, left and total lung image field. Fig. (1a) shows the regions of the left, right, and total lung where only the pixels with the resistivity changes greater than 3% were chosen. Fig. (1,b) shows two local regions of 8x8 pixels where all the pixels were included without considering the resistivity changes. Area 1 and area 2 in the right lung were selected based on the MR images and the locations are the same for three electrode planes. The ROIs were determined for all subjects for each electrode planes and body positions.


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)

Image (a) shows the automatically selected right lung (outlined in red), left lung and total lung image with a threshold of 3%. Image (b) shows the two local regions in the right lung (8x8 pixels), labeled 1 and 2. The center of area 1 lies in the middle of the left half of image b. Area 2 is area 1 repositioned 45 degrees counter clockwise. The resistivity changes in these two regions are the mean of all the pixels. R: right, L: left, P: posterior, A: anterior.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Image (a) shows the automatically selected right lung (outlined in red), left lung and total lung image with a threshold of 3%. Image (b) shows the two local regions in the right lung (8x8 pixels), labeled 1 and 2. The center of area 1 lies in the middle of the left half of image b. Area 2 is area 1 repositioned 45 degrees counter clockwise. The resistivity changes in these two regions are the mean of all the pixels. R: right, L: left, P: posterior, A: anterior.
Mentions: Resistivity changes were calculated for two local regions in the right lung (8x8 pixels) [10, 11] and for the right, left and total lung image field. Fig. (1a) shows the regions of the left, right, and total lung where only the pixels with the resistivity changes greater than 3% were chosen. Fig. (1,b) shows two local regions of 8x8 pixels where all the pixels were included without considering the resistivity changes. Area 1 and area 2 in the right lung were selected based on the MR images and the locations are the same for three electrode planes. The ROIs were determined for all subjects for each electrode planes and body positions.

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.