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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
Effect of field of view on accuracy of airway wall measurement. All images were reconstructed with use of standard kernel (B50f) and 0.75 mm slice thickness. Measured airway wall thicknesses on CT image with various field of views are not significantly different from actual wall thicknesses. Even with use of smaller field of view, measurement accuracy of wall thicknesses less than 1 mm was not improved.
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Figure 4: Effect of field of view on accuracy of airway wall measurement. All images were reconstructed with use of standard kernel (B50f) and 0.75 mm slice thickness. Measured airway wall thicknesses on CT image with various field of views are not significantly different from actual wall thicknesses. Even with use of smaller field of view, measurement accuracy of wall thicknesses less than 1 mm was not improved.

Mentions: The measured airway wall thicknesses on CT images with various FOVs were not significantly different from the actual wall thicknesses (Table 3). There were rapidly increasing errors of the airway wall measurement when the thickness of the phantom was less than 1 mm. Even with the use of a smaller FOV, the measurement accuracy of wall thicknesses of less than 1 mm could not be improved (Fig. 4). Similarly, slice thickness did not affect the measurement accuracy (Fig. 5). The measured airway wall thicknesses determined with the various reconstructed slice thicknesses were not significantly different from the actual wall thicknesses (Table 3).


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)

Effect of field of view on accuracy of airway wall measurement. All images were reconstructed with use of standard kernel (B50f) and 0.75 mm slice thickness. Measured airway wall thicknesses on CT image with various field of views are not significantly different from actual wall thicknesses. Even with use of smaller field of view, measurement accuracy of wall thicknesses less than 1 mm was not improved.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Effect of field of view on accuracy of airway wall measurement. All images were reconstructed with use of standard kernel (B50f) and 0.75 mm slice thickness. Measured airway wall thicknesses on CT image with various field of views are not significantly different from actual wall thicknesses. Even with use of smaller field of view, measurement accuracy of wall thicknesses less than 1 mm was not improved.
Mentions: The measured airway wall thicknesses on CT images with various FOVs were not significantly different from the actual wall thicknesses (Table 3). There were rapidly increasing errors of the airway wall measurement when the thickness of the phantom was less than 1 mm. Even with the use of a smaller FOV, the measurement accuracy of wall thicknesses of less than 1 mm could not be improved (Fig. 4). Similarly, slice thickness did not affect the measurement accuracy (Fig. 5). The measured airway wall thicknesses determined with the various reconstructed slice thicknesses were not significantly different from the actual wall thicknesses (Table 3).

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