Lung CT Densitometry in Systemic Sclerosis: Correlation With Lung Function, Exercise Testing, and Quality of Life

doi:10.1378/chest.06-1401

Chest

Volume 131, Issue 3, March 2007, Pages 672-681

https://doi.org/10.1378/chest.06-1401 Get rights and content

Abstract

Background:To ascertain if analysis of lung density histograms in thin-section CT was more reproducible than visual assessment of lung changes in systemic sclerosis (SSc), and if such density histogram parameters as mean lung attenuation (MLA), skewness, and kurtosis could more closely reflect pulmonary function as well as exercise and quality of life impairment.

Methods:The intraoperator and interoperator reproducibility of visual and densitometric lung CT analysis in 48 SSc patients examined with CT were evaluated by means of weighted κ statistics. Univariate and multivariate regression analyses were applied to evaluate the relationship of visual and densitometric CT measurements with functional parameters including functional residual capacity (FRC), FVC, FEV₁, diffusion capacity of the lung for carbon monoxide (Dlco), 6-min walking testing (6MWT), and health-related quality of life questionnaire (QLQ) parameters.

Results:The intraoperator and interoperator reproducibility of MLA (intraobserver weighted κ = 0.97; interobserver weighted κ = 0.96), skewness (intraobserver weighted κ = 0.89; interobserver weighted κ = 0.88), and kurtosis (intraobserver weighted κ = 0.89; interobserver weighted κ = 0.88) were higher than those of visual assessment (intraobserver weighted κ = 0.71; interobserver weighted κ = 0.69). In univariate analysis, only densitometric measurements were correlated with some exercise and QLQ parameters. In multivariate analysis, MLA (square regression coefficient corrected [R²c] = 0.70), skewness (R²c = 0.78), and kurtosis (R²c = 0.77) were predicted by FRC, FVC, Dlco, 6MWT, and QLQ parameters, while visual assessment was associated only with FRC and FVC (R²c = 0.40).

Conclusions:In SSc, densitometric analysis is more reproducible than visual assessment of lung changes in thin-section CT and more closely correlated to pulmonary function testing, 6MWT, and QLQ. Density histogram parameters may be useful for cross-sectional and longitudinal studies of lung involvement in SSc.

Section snippets

Selection of Patients

We enrolled 48 consecutive SSc patients from May 2004 to December 2004 (42 women; mean age, 57 ± 13 years [± SD]; range, 18 to 80 years; disease duration, 146 ± 119 months; range, 1 to 524 months). Thirty-three patients were classified as having limited SSc (mean age, 60 ± 12 years; range, 29 to 80 years; disease duration, 166 ± 131 months; range, 1 to 524 months), and 15 patients were classified as having diffuse SSc (mean age, 51 ± 14 years; range, 18 to 66 years; disease duration, 104 ± 78

Results

This study was conducted according to the Strengthening the Reporting of Observational Studies in Epidemiology statement.²⁹All patients completed the study. Clinical, functional, and CT data are summarized inTable 1.Fig 1 shows thin-section CT scans and lung density histograms in a patient with a visual score of 3 and in a patient with a visual score of 24, with decreased skewness and kurtosis and increased MLA in the latter.

Table 2 reports QLQ items, 6MWT, functional data, and CT findings in

Discussion

The results of this study indicate that lung density histogram parameters are more reproducible than visual assessment of thin-section CT and are more closely related to functional, exercise, and quality of life impairment in SSc. HRCT is the pivotal radiologic evaluation in interstitial lung disease because of its greater sensitivity as compared to chest radiography, especially for early changes.14, 30, 31A differential diagnosis among the various clinical conditions causing pulmonary fibrosis

Acknowledgments

The authors thank Luca Ermini, Technician of Respiratory Medicine Laboratory, for his contribution in pulmonary function and exercise testing

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CT evaluation of interstitial lung disease related to systemic sclerosis: visual versus automated assessment. A systematic review
2024, Clinical Radiology
To identify similarities and differences between visual (VA) and automated assessment (AA) of systemic sclerosis-related interstitial lung disease (SSc-ILD) at chest computed tomography (CT) in terms of clinical applicability.
Medline, Embase, and Web of Science were searched to identify all studies investigating VA and AA for SSc-ILD assessment, from inception to 31 July 2022. Exclusion criteria were manuscripts not in English, absence of full-text, reviews, diseases other than ILD in SSc, CT not analysed with both VA and AA, VA and AA not adopted for the same purpose or not compared, overlap syndromes, SSc-ILD data not extractable, and studies with <10 patients.
Ten full-text studies (804 patients) were included. The most adopted VAs were the Warrick or Goh score (four studies each), while densitometry (eight studies) or lung texture analysis (LTA, two studies) were utilised as AAs. The main field of investigation was the correlation with baseline pulmonary function tests (PFT, six studies). Warrick VA showed lower correlations compared to densitometry, while Goh VA demonstrated more heterogeneous results. Compared to LTA, Goh VA obtained lower correlations with lung volumes but similar or stronger coefficients with alveolar diffusibility.
VA and AA may show heterogeneous results comparing their correlations with PFT, probably depending on the specific analysis adopted for each method. More data are needed on VA versus LTA. Comparisons between VA and AA regarding correlation with PFT follow-up and as prognostic elements, or for disease monitoring, are lacking. AAs in progressive fibrosis diagnosis remain to be tested.
Heterogeneity of Lung Density in Patients With Chronic Thromboembolic Pulmonary Hypertension (CTEPH)
2022, Academic Radiology
Pulmonary endarterectomy (PEA) is one of the most effective treatments for chronic thromboembolic pulmonary hypertension (CTEPH). Right heart catheterization (RHC) is the gold standard assessment for pulmonary circulatory dynamics. However, computed tomography (CT) is less invasive than RHC and can elucidate some of the morphological changes caused by thromboembolism. We hypothesized that CT could facilitate the evaluation of heterogeneous pulmonary perfusion. This study investigated whether CT imaging features reflect the disease severity and changes in pulmonary circulatory dynamics in patients with CTEPH before and after PEA.
This retrospective study included 58 patients with CTEPH who underwent PEA. Pre-PEA and post-PEA CT images were assessed for heterogeneity using CT texture analysis (CTTA). The CT parameters were compared with the results of the RHC and other clinical indices and analyzed with receiver operating characteristic curves analysis for patients with and without residual pulmonary hypertension (PH) (post-PEA mean pulmonary artery pressure ≥ 25 mmHg).
CT measurements reflecting heterogeneity were significantly correlated with mean pulmonary artery pressure. Kurtosis, skewness, and uniformity were significantly lower, and entropy was significantly higher in patients with residual PH than patients without residual PH. Area under the curve values of pre-PEA and post-PEA entropy between patients with and without residual PH were 0.71 (95% confidence interval 0.57–0.84) and 0.75 (0.63–0.88), respectively.
Heterogeneity of lung density might reflect pulmonary circulatory dynamics, and CTTA for heterogeneity could be a less invasive technique for evaluation of changes in pulmonary circulatory dynamics in patients with CTEPH undergoing PEA.
A Convolutional Neural Network Approach to Quantify Lung Disease Progression in Patients with Fibrotic Hypersensitivity Pneumonitis (HP)
2022, Academic Radiology
Citation Excerpt :
Increased lung fibrosis and decreased ground-glass opacities on serial CT images were associated with disease progression. Previous studies have shown that in patients with lung fibrosis, histogram statistics correlate with physiologic parameters at baseline, including FVC and DLCO (12,13,33), but also that these metrics, as coarse global measures, are not able to localize interstitial lung disease on CT images and therefore are not sufficiently precise for longitudinal analysis (17). In the current study, histogram measures were highly correlated to spirometry changes over time, but we also note that our radiology database was extracted from a single-center and acquired with the same acquisition protocol.
Rationale and Objectives To evaluate associations between longitudinal changes of quantitative CT parameters and spirometry in patients with fibrotic hypersensitivity pneumonitis (HP).
Materials and Methods Serial CT images and spirometric data were retrospectively collected in a group of 25 fibrotic HP patients. Quantitative CT analysis included histogram parameters (median, interquartile range, skewness, and kurtosis) and a pretrained convolutional neural network (CNN)-based textural analysis, aimed at quantifying the extent of consolidation (C), fibrosis (F), ground-glass opacity (GGO), low attenuation areas (LAA) and healthy tissue (H).
Results At baseline, FVC was 61(44-70) %pred. The median follow-up period was 1.4(0.8-3.2) years, with 3(2-4) visits per patient. Over the study, 8 patients (32%) showed a FVC decline of more than 5%, a significant worsening of all histogram parameters (p≤0.015) and an increased extent of fibrosis via CNN (p=0.038). On histogram analysis, decreased skewness and kurtosis were the parameters most strongly associated with worsened FVC (respectively, r2=0.63 and r2=0.54, p<0.001). On CNN classification, increased extent of fibrosis and consolidation were the measures most strongly correlated with FVC decline (r2=0.54 and r2=0.44, p<0.001).
Conclusion CT histogram and CNN measurements provide sensitive measures of functional changes in fibrotic HP patients over time. Increased fibrosis was associated with FVC decline, providing index of disease progression. CNN may help improve fibrotic HP follow-up, providing a sensitive tool for progressive interstitial changes, which can potentially contribute to clinical decisions for individualizing disease management.
Early Radiographic Progression of Scleroderma: Lung Disease Predicts Long-term Mortality
2022, Chest
Radiographic end points commonly are included in therapeutic trials for systemic sclerosis (SSc)-interstitial lung disease (ILD); however, the relationship between these outcomes and long-term mortality is unclear.
Do short-term changes in radiographic measures of ILD predict long-term survival in patients with SSc?
The Scleroderma Lung Study (SLS) I and II evaluated the safety and efficacy of cyclophosphamide (in SLS I and II) and mycophenolate mofetil (in SLS II) for the treatment of SSc-ILD. Changes in the extent of ILD over time were assessed on high-resolution CT scans of the chest by quantitative image analysis, an approach that applies a computer-based algorithm to assess changes in the radiographic extent of ILD objectively. Participants subsequently were followed for up to 12 years (SLS I) and 8 years (SLS II). Cox proportional hazards models determined whether the change in the quantitative radiographic extent of ILD predicted survival, adjusting for other known predictors of survival.
Among SLS I and II participants, 82 and 90 had follow-up imaging scans, respectively, and were included in the analysis. Participants in both trials who showed an increase in the total quantitative radiographic extent of ILD scores of ≥ 2% at 12 months (SLS I) or 24 months (SLS II) experienced significantly worse long-term survival than those with change scores of < 2% (P ≤ .01, log-rank test). In the multivariate Cox models, radiographic progression remained associated with worse long-term survival in SLS I (P = .089) and SLS II (P = .014).
Data from two independent clinical trial cohorts with extensive long-term follow-up demonstrated that radiographic progression of ILD over 12 to 24 months, in both treatment and placebo arms, can predict increased risk for long-term mortality in patients with SSc. These findings suggest that radiographic end points may serve as surrogates for mortality in SSc-ILD.
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The authors have no conflicts of interest to disclose.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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Chest

Original Research: Interstitial Lung DiseaseLung CT Densitometry in Systemic Sclerosis: Correlation With Lung Function, Exercise Testing, and Quality of Life

Abstract

Section snippets

Selection of Patients

Results

Discussion

Acknowledgments

Am J Med

Dis Chest

Am J Med

Acad Radiol

Clin Chest Med

Chest

Clin Radiol

Chest

Eur J Radiol

High resolution computed tomography as a predictor of lung histology in systemic sclerosis

Thorax

Serial CT in fibrosing alveolitis: prognostic significance of the initial pattern

AJR Am J Roentgenol

The predictive value of appearances on thin-section computed tomography in fibrosing alveolitis

Am Rev Respir Dis

Vascular involvement in systemic sclerosis (SSc)

Clin Exp Rheumatol

Early detection of pulmonary arterial hypertension in systemic sclerosis: a French nationwide prospective multicenter study

Arthritis Rheum

Scleroderma (systemic sclerosis): classification, subsets and pathogenesis

J Rheumatol

Pulmonary involvement in progressive systemic sclerosis: sequential evaluation with CT, pulmonary function tests and bronchoalveolar lavage

Radiology

Fibrosing alveolitis in systemic sclerosis: indices of lung function in relation to extent of disease on computed tomography

Arthritis Rheum

High resolution computed tomography in early scleroderma lung disease

J Rheumatol

Original Research: Interstitial Lung Disease
Lung CT Densitometry in Systemic Sclerosis: Correlation With Lung Function, Exercise Testing, and Quality of Life