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Semi-automatic measurement of the airway dimension by computed tomography using the full-width-half-maximum method: a study on the measurement accuracy according to the CT parameters and size of the airway.

Kim N, Seo JB, Song KS, Chae EJ, Kang SH - Korean J Radiol (2008 May-Jun)

Bottom Line: The measured values as determined by CT and the actual dimensions of the tubes were compared.There was no significant difference in accuracy among images with the use of variable slice thicknesses or a variable FOV.Below a 1-mm threshold, the measurement failed to represent the change of the real dimensions.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

ABSTRACT

Objective: To assess the influence of variable factors such as the size of the airway and the CT imaging parameters such as the reconstruction kernel, field-of-view (FOV), and slice thickness on the automatic measurement of airway dimension.

Materials and methods: An airway phantom was fabricated that contained eleven poly-acryl tubes of various lumen diameters and wall thicknesses. The measured density of the poly-acryl wall was 150 HU, and the measured density of the airspace filled with polyurethane foam was -900 HU. CT images were obtained using a 16-MDCT (multidetector CT) scanner and were reconstructed with various reconstruction kernels, thicknesses and FOV. The luminal radius and wall thickness were measured using in-house software based on the full-width-half-maximum method. The measured values as determined by CT and the actual dimensions of the tubes were compared.

Results: Measurements were most accurate on images reconstructed with use of a standard kernel (mean error: -0.03 +/- 0.21 mm for wall thickness and -0.12 +/- 0.11 mm for the luminal radius). There was no significant difference in accuracy among images with the use of variable slice thicknesses or a variable FOV. Below a 1-mm threshold, the measurement failed to represent the change of the real dimensions.

Conclusion: Measurement accuracy was strongly influenced by the specific reconstruction kernel utilized. For accurate measurement, standardization of the imaging protocol and selection of the appropriate anatomic level are essential.

Show MeSH
Poly-acryl airway phantom and scanned CT image.A. Eleven poly-acryl artificial tubes of physical phantom with various inner diameters and wall thicknesses. Measured CT density of material was 150 HU.B. Physical phantom is filled with polyurethane foam.C. Axial CT image of phantom.
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Figure 1: Poly-acryl airway phantom and scanned CT image.A. Eleven poly-acryl artificial tubes of physical phantom with various inner diameters and wall thicknesses. Measured CT density of material was 150 HU.B. Physical phantom is filled with polyurethane foam.C. Axial CT image of phantom.

Mentions: The actual dimensions of the tubes are shown in Table 1. The ranges of the inner lumen radius and the outer lumen radius were from 0.63 mm to 4.23 mm and from 1.08 mm to 6.04 mm, respectively. The range of the wall thickness was from 0.45 mm to 3.08 mm. Figure 1 presents the physical phantom with and without polyurethane foam. The representative CT image of the phantom was scanned at an angle perpendicular to the axis of the tubes.


Semi-automatic measurement of the airway dimension by computed tomography using the full-width-half-maximum method: a study on the measurement accuracy according to the CT parameters and size of the airway.

Kim N, Seo JB, Song KS, Chae EJ, Kang SH - Korean J Radiol (2008 May-Jun)

Poly-acryl airway phantom and scanned CT image.A. Eleven poly-acryl artificial tubes of physical phantom with various inner diameters and wall thicknesses. Measured CT density of material was 150 HU.B. Physical phantom is filled with polyurethane foam.C. Axial CT image of phantom.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2627250&req=5

Figure 1: Poly-acryl airway phantom and scanned CT image.A. Eleven poly-acryl artificial tubes of physical phantom with various inner diameters and wall thicknesses. Measured CT density of material was 150 HU.B. Physical phantom is filled with polyurethane foam.C. Axial CT image of phantom.
Mentions: The actual dimensions of the tubes are shown in Table 1. The ranges of the inner lumen radius and the outer lumen radius were from 0.63 mm to 4.23 mm and from 1.08 mm to 6.04 mm, respectively. The range of the wall thickness was from 0.45 mm to 3.08 mm. Figure 1 presents the physical phantom with and without polyurethane foam. The representative CT image of the phantom was scanned at an angle perpendicular to the axis of the tubes.

Bottom Line: The measured values as determined by CT and the actual dimensions of the tubes were compared.There was no significant difference in accuracy among images with the use of variable slice thicknesses or a variable FOV.Below a 1-mm threshold, the measurement failed to represent the change of the real dimensions.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

ABSTRACT

Objective: To assess the influence of variable factors such as the size of the airway and the CT imaging parameters such as the reconstruction kernel, field-of-view (FOV), and slice thickness on the automatic measurement of airway dimension.

Materials and methods: An airway phantom was fabricated that contained eleven poly-acryl tubes of various lumen diameters and wall thicknesses. The measured density of the poly-acryl wall was 150 HU, and the measured density of the airspace filled with polyurethane foam was -900 HU. CT images were obtained using a 16-MDCT (multidetector CT) scanner and were reconstructed with various reconstruction kernels, thicknesses and FOV. The luminal radius and wall thickness were measured using in-house software based on the full-width-half-maximum method. The measured values as determined by CT and the actual dimensions of the tubes were compared.

Results: Measurements were most accurate on images reconstructed with use of a standard kernel (mean error: -0.03 +/- 0.21 mm for wall thickness and -0.12 +/- 0.11 mm for the luminal radius). There was no significant difference in accuracy among images with the use of variable slice thicknesses or a variable FOV. Below a 1-mm threshold, the measurement failed to represent the change of the real dimensions.

Conclusion: Measurement accuracy was strongly influenced by the specific reconstruction kernel utilized. For accurate measurement, standardization of the imaging protocol and selection of the appropriate anatomic level are essential.

Show MeSH