Dataset Information

SPIROMICS Protocol for Multicenter Quantitative Computed Tomography to Phenotype the Lungs.

ABSTRACT: Multidetector row computed tomography (MDCT) is increasingly taking a central role in identifying subphenotypes within chronic obstructive pulmonary disease (COPD), asthma, and other lung-related disease populations, allowing for the quantification of the amount and distribution of altered parenchyma along with the characterization of airway and vascular anatomy. The embedding of quantitative CT (QCT) into a multicenter trial with a variety of scanner makes and models along with the variety of pressures within a clinical radiology setting has proven challenging, especially in the context of a longitudinal study. SPIROMICS (Subpopulations and Intermediate Outcome Measures in COPD Study), sponsored by the National Institutes of Health, has established a QCT lung assessment system (QCT-LAS), which includes scanner-specific imaging protocols for lung assessment at total lung capacity and residual volume. Also included are monthly scanning of a standardized test object and web-based tools for subject registration, protocol assignment, and data transmission coupled with automated image interrogation to assure protocol adherence. The SPIROMICS QCT-LAS has been adopted and contributed to by a growing number of other multicenter studies in which imaging is embedded. The key components of the SPIROMICS QCT-LAS along with evidence of implementation success are described herein. While imaging technologies continue to evolve, the required components of a QCT-LAS provide the framework for future studies, and the QCT results emanating from SPIROMICS and the growing number of other studies using the SPIROMICS QCT-LAS will provide a shared resource of image-derived pulmonary metrics.

SUBMITTER: Sieren JP

PROVIDER: S-EPMC5074650 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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SPIROMICS Protocol for Multicenter Quantitative Computed Tomography to Phenotype the Lungs.

Sieren Jered P JP Newell John D JD Barr R Graham RG Bleecker Eugene R ER Burnette Nathan N Carretta Elizabeth E EE Couper David D Goldin Jonathan J Guo Junfeng J Han MeiLan K MK Hansel Nadia N NN Kanner Richard E RE Kazerooni Ella A EA Martinez Fernando J FJ Rennard Stephen S Woodruff Prescott G PG Hoffman Eric A EA

American journal of respiratory and critical care medicine 20161001 7

Multidetector row computed tomography (MDCT) is increasingly taking a central role in identifying subphenotypes within chronic obstructive pulmonary disease (COPD), asthma, and other lung-related disease populations, allowing for the quantification of the amount and distribution of altered parenchyma along with the characterization of airway and vascular anatomy. The embedding of quantitative CT (QCT) into a multicenter trial with a variety of scanner makes and models along with the variety of p ...[more]

PMID: 27482984

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Project description:ObjectivesThe purposes of this study were to evaluate the reference range of quantitative computed tomography (QCT) measures of lung attenuation and airway parameter measurements in healthy nonsmoking adults and to identify sources of variation in those measures and possible means to adjust for them.Materials and methodsWithin the COPDGene study, 92 healthy non-Hispanic white nonsmokers (29 men, 63 women; mean [SD] age, 62.7 [9.0] years; mean [SD] body mass index [BMI], 28.1 [5.1] kg/m(2)) underwent volumetric computed tomography (CT) at full inspiration and at the end of a normal expiration. On QCT analysis (Pulmonary Workstation 2, VIDA Diagnostics), inspiratory low-attenuation areas were defined as lung tissue with attenuation values -950 Hounsfield units or less on inspiratory CT (LAA(I-950)). Expiratory low-attenuation areas were defined as lung tissue -856 Hounsfield units or less on expiratory CT (LAA(E-856)). We used simple linear regression to determine the impact of age and sex on QCT parameters and multiple regression to assess the additional impact of total lung capacity and functional residual capacity measured by CT (TLC(CT) and FRC(CT)), scanner type, and mean tracheal air attenuation. Airways were evaluated using measures of airway wall thickness, inner luminal area, wall area percentage (WA%), and standardized thickness of an airway with inner perimeter of 10 mm (Pi10).ResultsMean (SD) %LAA(I-950) was 2.0% (2.7%), and mean (SD) %LAA(E-856) was 9.2% (6.8%). Mean (SD) %LAA(I-950) was 3.6% (3.2%) in men, compared with 1.3% (2.0%) in women (P < 0.001). The %LAA(I-950) did not change significantly with age (P = 0.08) or BMI (P = 0.52). %LAA(E-856) did not show any independent relationship with age (P = 0.33), sex (P = 0.70), or BMI (P = 0.32). On multivariate analysis, %LAA(I-950) showed a direct relationship to TLC(CT) (P = 0.002) and an inverse relationship to mean tracheal air attenuation (P = 0.003), and %LAA(E-856) was related to age (P = 0.001), FRC(CT) (P = 0.007), and scanner type (P < 0.001). Multivariate analysis of segmental airways showed that inner luminal area and WA% were significantly related to TLC(CT) (P < 0.001) and age (0.006). Moreover, WA% was associated with sex (P = 0.05), axial pixel size (P = 0.03), and slice interval (P = 0.04). Lastly, airway wall thickness was strongly influenced by axial pixel size (P < 0.001).ConclusionsAlthough the attenuation characteristics of normal lung differ by age and sex, these differences do not persist on multivariate analysis. Potential sources of variation in measurement of attenuation-based QCT parameters include depth of inspiration/expiration and scanner type. Tracheal air attenuation may partially correct variation because of scanner type. Sources of variation in QCT airway measurements may include age, sex, BMI, depth of inspiration, and spatial resolution.

Project description:ObjectivesWe aimed to study sirolimus-related lung parenchymal changes by quantitative analysis of computed tomography (CT) of the lungs in patients with lymphangioleiomyomatosis (LAM).MethodsWe studied 20 participants from the Multicenter Lymphangioleiomyomatosis Sirolimus Trial for Safety study, who had undergone both thin-section CT scans and pulmonary function tests at baseline, 12, and 24 months. Quantitative CT parameters such as CT-derived total lung capacity, percentage of low attenuation area (LAA%), lung density histogram, fractal property of low attenuation area, and airway dimensions were analyzed, and correlations were conducted between the longitudinal change in each quantitative CT measurement and changes in pulmonary function were examined. Among 20 participants, pre-trial (n = 8) and post-trial (n = 16) CT data were also analyzed to deduce pathophysiologic implications of the serial changes in CT parameters during trial periods.ResultsFEV1 significantly increased from baseline to 24 months (slope 3.71 ± 1.50 ml/month) whereas FVC didn't during sirolimus therapy. Strikingly, LAA%, and skewness and kurtosis of density histogram significantly increased from baseline to 24 months, while mean and mode CT values significantly decreased from baseline to 24 months. Statistically significant positive correlations were found between ΔFEV1 and Δskewness (r = 0.465, p = 0.045). Taking the changes in lung density during pre-trial period into consideration, sirolimus decreases the area of -800 to -750 Housefield unit (HU) density and inhibits the decrease of -950 to -800 HU area during treatment, then producing the increased LAA% during the trial and post-trial periods. Given few sirolimus-related changes in airway dimensions, possible changes in lung mechanics may have contributed to increased FEV1.ConclusionOur study suggests that the lung density histogram parameters, kurtosis, and skewness, may be useful as indicators of the efficacy of sirolimus.

Dataset Information

SPIROMICS Protocol for Multicenter Quantitative Computed Tomography to Phenotype the Lungs.

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SPIROMICS Protocol for Multicenter Quantitative Computed Tomography to Phenotype the Lungs.

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