Dataset Information

CT Imaging-Based Low-Attenuation Super Clusters in Three Dimensions and the Progression of Emphysema.

ABSTRACT: BACKGROUND:Distributions of low-attenuation areas in two-dimensional (2-D) CT lung slices are used to quantify parenchymal destruction in patients with COPD. However, these segmental approaches are limited and may not reflect the true three-dimensional (3-D) tissue processes that drive emphysematous changes in the lung. The goal of this study was to instead evaluate distributions of 3-D low-attenuation volumes, which we hypothesized would follow a power law distribution and provide a more complete assessment of the mechanisms underlying disease progression. METHODS:CT scans and pulmonary function test results were acquired from an observational database for N = 12 patients with COPD and N = 12 control patients. The data set included baseline and two annual follow-up evaluations in patients with COPD. Three-dimensional representations of the lungs were reconstructed from 2-D axial CT slices, with low-attenuation volumes identified as contiguous voxels < -960 Hounsfield units. RESULTS:Low-attenuation sizes generally followed a power law distribution, with the exception of large, individual outliers termed "super clusters," which deviated from the expected distribution. Super cluster volume was correlated with disease severity (% total low attenuation, ? = 0.950) and clinical measures of lung function including FEV1 (? = -0.849) and diffusing capacity of the lung for carbon monoxide Dlco (? = -0.874). To interpret these results, we developed a personalized computational model of super cluster emergence. Simulations indicated disease progression was more likely to occur near existing emphysematous regions, giving rise to a biomechanical, force-induced mechanism of super cluster growth. CONCLUSIONS:Low-attenuation super clusters are defining, quantitative features of parenchymal destruction that dominate disease progression, particularly in advanced COPD.

SUBMITTER: Mondonedo JR

PROVIDER: S-EPMC6344385 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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CT Imaging-Based Low-Attenuation Super Clusters in Three Dimensions and the Progression of Emphysema.

Mondoñedo Jarred R JR Sato Susumu S Oguma Tsuyoshi T Muro Shigeo S Sonnenberg Adam H AH Zeldich Dean D Parameswaran Harikrishnan H Hirai Toyohiro T Suki Béla B

Chest 20181005 1

<h4>Background</h4>Distributions of low-attenuation areas in two-dimensional (2-D) CT lung slices are used to quantify parenchymal destruction in patients with COPD. However, these segmental approaches are limited and may not reflect the true three-dimensional (3-D) tissue processes that drive emphysematous changes in the lung. The goal of this study was to instead evaluate distributions of 3-D low-attenuation volumes, which we hypothesized would follow a power law distribution and provide a mor ...[more]

PMID: 30292758

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Project description:Rationale and objectivesEmphysema is characterized by lung tissue destruction and trapped gas. On computed tomographic (CT) images, this may be expressed by widespread areas with high specific gas volume (SV(g)). SV(g) is highly sensitive to very low attenuation values, which frequently occur in the CT images of patients with severe emphysema. The purpose of the present work was to study if and how different reconstruction settings and different scanners significantly influence SV(g) distribution, particularly in the very low attenuation range.Materials and methodsTwo sets of CT images taken from two different CT scanners at two different lung volumes in 10 healthy volunteers and 18 subjects with severe emphysema were analyzed. Images were reconstructed using two different settings of reconstruction parameters: (1) thin slice thickness and sharp filter and (2) thick slice thickness and smooth filter. For each set of images, average values of SV(g) and their variation (?SV(g)) from total lung capacity to residual volume were calculated in the whole lung.ResultsVery low attenuation values are always present in CT images when reconstructed with thin slice thickness and a sharp filter and in very large numbers in patients with severe emphysema. SV(g) values were in general significantly higher in patients with emphysema than in healthy subjects, at both total lung capacity and residual volume (P < .001), and were significantly influenced by the reconstruction filter (P < .001) and CT scanner (P < .001). ?SV(g) was lower in patients with emphysema than in healthy subjects (P < .001) and was significantly affected by the reconstruction setting but not by the CT scanner.ConclusionsThe disproportionate effect of low-attenuation pixels on SV(g) likely causes overestimation of the severity of emphysema and trapped gas. This can be significantly reduced, however, by using thick slices and a smooth filter for image reconstruction. ?SV(g) is generally robust for quantifying the functional impairment of the lung in severe emphysema.

Dataset Information

CT Imaging-Based Low-Attenuation Super Clusters in Three Dimensions and the Progression of Emphysema.

Publications

CT Imaging-Based Low-Attenuation Super Clusters in Three Dimensions and the Progression of Emphysema.

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