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Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease
BACKGROUND: The fractal dimension characterizing the cumulative size distribution of low attenuation area (LAA) clusters, identified with a fixed threshold such as − 950 Hounsfield Units (HU), on computed tomography (CT) sensitively detects parenchymal destruction in chronic obstructive pulmonary di...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116481/ https://www.ncbi.nlm.nih.gov/pubmed/30157833 http://dx.doi.org/10.1186/s12890-018-0714-5 |
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author | Tanabe, Naoya Muro, Shigeo Sato, Susumu Oguma, Tsuyoshi Sato, Atsuyasu Hirai, Toyohiro |
author_facet | Tanabe, Naoya Muro, Shigeo Sato, Susumu Oguma, Tsuyoshi Sato, Atsuyasu Hirai, Toyohiro |
author_sort | Tanabe, Naoya |
collection | PubMed |
description | BACKGROUND: The fractal dimension characterizing the cumulative size distribution of low attenuation area (LAA) clusters, identified with a fixed threshold such as − 950 Hounsfield Units (HU), on computed tomography (CT) sensitively detects parenchymal destruction in chronic obstructive pulmonary disease (COPD) even when the percent LAA (LAA%), a standard emphysema index, is unchanged. This study examines whether the cumulative size distribution of LAA clusters, defined with thresholds of the 15th, 25th, and 35th percentiles of a CT density histogram instead of the fixed-threshold of − 950 HU, exhibits a fractal property and whether its fractal dimension (D’15, D’25, and D’35, respectively) provides additional structural information in emphysematous lungs that is difficult to detect with the conventional − 950-HU-based fractal dimension (D950). METHODS: Chest inspiratory CT scans and pulmonary functions were cross-sectionally examined in 170 COPD subjects. A proxy for the inspiration level at CT scan was obtained by dividing CT-measured total lung volume (CT-TLV) by physiologically measured total lung capacity. Moreover, long-term (> 5 years) changes in D950 and the new fractal dimensions were longitudinally evaluated in 17 current and 42 former smokers with COPD. RESULTS: D950, but not D’15, D’25, or D’35 was weakly correlated with the proxy for the inspiration. D950, D’25, and D’35 but not D’15 correlated with LAA% and diffusion capacity. In the long-term longitudinal study, LAA% was increased and D950 and D’35 were decreased in both current and former smokers, while D’25 was decreased only in current smokers and D’15 was not changed in either group. The longitudinal changes in D’25 but not those in LAA%, D950, D’15, and D’35 were greater in current smokers than in former smokers. This greater change in D’25 in current smokers was confirmed after adjusting the change in CT-TLV and the baseline D’25. CONCLUSIONS: D’25 reflects diffusion capacity in emphysematous lungs and is robust against inspiration levels during CT scans. This new fractal dimension might provide additional structural information that is difficult to detect with the conventional D950 and LAA% and allow for more sensitive evaluation of emphysema progression over time. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12890-018-0714-5) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-6116481 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-61164812018-10-02 Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease Tanabe, Naoya Muro, Shigeo Sato, Susumu Oguma, Tsuyoshi Sato, Atsuyasu Hirai, Toyohiro BMC Pulm Med Research Article BACKGROUND: The fractal dimension characterizing the cumulative size distribution of low attenuation area (LAA) clusters, identified with a fixed threshold such as − 950 Hounsfield Units (HU), on computed tomography (CT) sensitively detects parenchymal destruction in chronic obstructive pulmonary disease (COPD) even when the percent LAA (LAA%), a standard emphysema index, is unchanged. This study examines whether the cumulative size distribution of LAA clusters, defined with thresholds of the 15th, 25th, and 35th percentiles of a CT density histogram instead of the fixed-threshold of − 950 HU, exhibits a fractal property and whether its fractal dimension (D’15, D’25, and D’35, respectively) provides additional structural information in emphysematous lungs that is difficult to detect with the conventional − 950-HU-based fractal dimension (D950). METHODS: Chest inspiratory CT scans and pulmonary functions were cross-sectionally examined in 170 COPD subjects. A proxy for the inspiration level at CT scan was obtained by dividing CT-measured total lung volume (CT-TLV) by physiologically measured total lung capacity. Moreover, long-term (> 5 years) changes in D950 and the new fractal dimensions were longitudinally evaluated in 17 current and 42 former smokers with COPD. RESULTS: D950, but not D’15, D’25, or D’35 was weakly correlated with the proxy for the inspiration. D950, D’25, and D’35 but not D’15 correlated with LAA% and diffusion capacity. In the long-term longitudinal study, LAA% was increased and D950 and D’35 were decreased in both current and former smokers, while D’25 was decreased only in current smokers and D’15 was not changed in either group. The longitudinal changes in D’25 but not those in LAA%, D950, D’15, and D’35 were greater in current smokers than in former smokers. This greater change in D’25 in current smokers was confirmed after adjusting the change in CT-TLV and the baseline D’25. CONCLUSIONS: D’25 reflects diffusion capacity in emphysematous lungs and is robust against inspiration levels during CT scans. This new fractal dimension might provide additional structural information that is difficult to detect with the conventional D950 and LAA% and allow for more sensitive evaluation of emphysema progression over time. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12890-018-0714-5) contains supplementary material, which is available to authorized users. BioMed Central 2018-08-29 /pmc/articles/PMC6116481/ /pubmed/30157833 http://dx.doi.org/10.1186/s12890-018-0714-5 Text en © The Author(s). 2018 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Article Tanabe, Naoya Muro, Shigeo Sato, Susumu Oguma, Tsuyoshi Sato, Atsuyasu Hirai, Toyohiro Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease |
title | Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease |
title_full | Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease |
title_fullStr | Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease |
title_full_unstemmed | Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease |
title_short | Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease |
title_sort | fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116481/ https://www.ncbi.nlm.nih.gov/pubmed/30157833 http://dx.doi.org/10.1186/s12890-018-0714-5 |
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