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Application of the homology method for quantification of low-attenuation lung region in patients with and without COPD

Authors Nishio M, Nakane K, Tanaka Y

Received 13 April 2016

Accepted for publication 30 May 2016

Published 6 September 2016 Volume 2016:11(1) Pages 2125—2137


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Richard Russell

Mizuho Nishio,1 Kazuaki Nakane,2 Yutaka Tanaka3

1Clinical PET Center, Institute of Biomedical Research and Innovation, Hyogo, Japan; 2Department of Molecular Pathology, Osaka University Graduate School of Medicine and Health Science, Osaka, Japan; 3Department of Radiology, Chibune General Hospital, Osaka, Japan

Background: Homology is a mathematical concept that can be used to quantify degree of contact. Recently, image processing with the homology method has been proposed. In this study, we used the homology method and computed tomography images to quantify emphysema.
Methods: This study included 112 patients who had undergone computed tomography and pulmonary function test. Low-attenuation lung regions were evaluated by the homology method, and homology-based emphysema quantification (b0, b1, nb0, nb1, and R) was performed. For comparison, the percentage of low-attenuation lung area (LAA%) was also obtained. Relationships between emphysema quantification and pulmonary function test results were evaluated by Pearson’s correlation coefficients. In addition to the correlation, the patients were divided into the following three groups based on guidelines of the Global initiative for chronic Obstructive Lung Disease: Group A, nonsmokers; Group B, smokers without COPD, mild COPD, and moderate COPD; Group C, severe COPD and very severe COPD. The homology-based emphysema quantification and LAA% were compared among these groups.
Results: For forced expiratory volume in 1 second/forced vital capacity, the correlation coefficients were as follows: LAA%, -0.603; b0, -0.460; b1, -0.500; nb0, -0.449; nb1, -0.524; and R, -0.574. For forced expiratory volume in 1 second, the coefficients were as follows: LAA%, -0.461; b0, -0.173; b1, -0.314; nb0, -0.191; nb1, -0.329; and R, -0.409. Between Groups A and B, difference in nb0 was significant (P-value = 0.00858), and those in the other types of quantification were not significant.
Conclusion: Feasibility of the homology-based emphysema quantification was validated. The homology-based emphysema quantification was useful for the assessment of emphysema severity.

Keywords: homology, emphysema, COPD, low-attenuation lung region

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