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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
Difference between actual and estimated airway luminal radius against actual airway luminal radius with use of various reconstructed kernels (B30f, B50f, and B70f). All images were reconstructed with 0.75-mm slice thickness and 360-mm field of view parameters.
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Figure 6: Difference between actual and estimated airway luminal radius against actual airway luminal radius with use of various reconstructed kernels (B30f, B50f, and B70f). All images were reconstructed with 0.75-mm slice thickness and 360-mm field of view parameters.

Mentions: Table 4 shows the difference between the estimated and the actual luminal radius with the use of the various reconstruction kernels with a 360-mm FOV and a 0.75-mm slice thickness. There is a clear underestimation bias when measuring the luminal radius on CT image reconstructed with a soft kernel (B10f) and an overestimation bias on CT images reconstructed with a sharp kernel (B70f and B80f). Figure 6 shows the differences between the actual and estimated airway luminal radii as compared to the actual airway luminal radii on the images reconstructed using various reconstruction kernels.


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)

Difference between actual and estimated airway luminal radius against actual airway luminal radius with use of various reconstructed kernels (B30f, B50f, and B70f). All images were reconstructed with 0.75-mm slice thickness and 360-mm field of view parameters.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Difference between actual and estimated airway luminal radius against actual airway luminal radius with use of various reconstructed kernels (B30f, B50f, and B70f). All images were reconstructed with 0.75-mm slice thickness and 360-mm field of view parameters.
Mentions: Table 4 shows the difference between the estimated and the actual luminal radius with the use of the various reconstruction kernels with a 360-mm FOV and a 0.75-mm slice thickness. There is a clear underestimation bias when measuring the luminal radius on CT image reconstructed with a soft kernel (B10f) and an overestimation bias on CT images reconstructed with a sharp kernel (B70f and B80f). Figure 6 shows the differences between the actual and estimated airway luminal radii as compared to the actual airway luminal radii on the images reconstructed using various reconstruction kernels.

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