The diagnostic trajectories of Danish patients with autoimmune rheumatologic disease associated interstitial lung disease: an interview-based study

Background

Autoimmune rheumatologic disease associated interstitial lung diseases (ARD-ILD) are rare conditions and the association between ARDs and respiratory symptoms often goes unrecognised by ARD patients and general practitioners (GPs). The diagnostic trajectory from the first respiratory symptoms to an ARD-ILD diagnosis is often delayed and may increase the burden of symptoms and allow further disease progression.The aim of this study was to 1) characterise the diagnostic trajectories of ARD-ILD patients and to 2) identify barriers for obtaining a timely ILD diagnosis based on the experiences and perceptions of both patients and healthcare professionals.

Method

Semi-structured qualitative interviews were conducted with Danish ARD-ILD patients, rheumatologists, pulmonologists and ILD nurses.

Results

Sixteen patients, six rheumatologists, three ILD nurses and three pulmonologists participated. Five characteristics of diagnostic trajectories were identified in the patient interviews: 1) early referral to lung specialists; 2) early delay; 3) delay or shortcut depending on specific circumstances; 4) parallel diagnostic trajectories connected late in the process; 5) early identification of lung involvement without proper interpretation. With the exception of early referral to lung specialists, all of the diagnostic trajectory characteristics identified led to delayed diagnosis. Delayed diagnostic trajectories resulted in patients experiencing increased uncertainty. Inconsistent disease terminology, insufficient knowledge and lack of awareness of ARD-ILD among central healthcare professionals and delayed referral to ILD specialists were main contributors to the diagnostic delay identified by the informants.

Conclusion

Five characteristics of the diagnostic trajectories were identified, four of which led to diagnostic delay of ARD-ILD. Improved diagnostic trajectories can shorten the diagnostic trajectory and increase early access to appropriate specialist medical care. Improved awareness and expertise in ARD-ILD across different medical specialties, especially among GPs, may contribute to more efficient and timely diagnostic trajectories and improved patient experiences.

Incidence, prevalence and regional distribution of systemic sclerosis and related interstitial lung Disease: A nationwide retrospective cohort study

Objective

To investigate incidence and prevalence of Systemic Sclerosis (SSc) and association with interstitial lung disease (SSc-ILD) in a nationwide population-based study.

Methods

Patients with an incident diagnosis of SSc in 2000–2016 were identified in the Danish National Patient Registry and categorised based on diagnosis of ILD. Incidence- and prevalence proportions were calculated based on the annual population estimates. A cox proportional hazards model was used to evaluate the association between age, sex, region and marital status and presence of ILD.

Results

In total, 1869 patients with SSc were identified; 275 patients (14.7%) had SSc-ILD. The majority of patients were females (75.5%). The percentage of males was higher in SSc-ILD than in SSc alone (30.9% and 23.4%, p = 0.008). Median time from SSc to ILD diagnosis was 1.4 years (range 0–14.2). ILD was diagnosed from ≤4 years before to ≥7 years after SSc. Development of ILD was associated with male gender (HR 1.75, 95% CI 1.15–2.66), age 41–50 (HR 1.81, 95% CI 1.07–3.05) and residency in the North Denmark Region (HR 1.95, 9 5% CI 1.12–3.40). Mean annual incidence proportion of SSc was 2.9/100,000 and mean annual prevalence proportion was 16.8/100,000. The incidence remained stable, but prevalence proportion increased from 14.1 – 16.5/100,000 in 2000–2008 to 17.9–19.2/100,000 in 2009–2016.

Conclusion

The prevalence of SSc increased during the study period, while the incidence remained stable. The prevalence of SSc-ILD was 14.7% and thus less frequent than expected. Male sex and age between 41 and 50 years were associated with ILD.

Longitudinal serological assessment of type VI collagen turnover is related to progression in a real-world cohort of idiopathic pulmonary fibrosis

Background

Remodeling of the extracellular matrix (ECM) is a central mechanism in the progression of idiopathic pulmonary fibrosis (IPF), and remodeling of type VI collagen has been suggested to be associated with disease progression. Biomarkers that reflect and predict the progression of IPF would provide valuable information for clinicians when treating IPF patients.

Methods

Two serological biomarkers reflecting formation (PRO-C6) and degradation (C6M) of type VI collagen were evaluated in a real-world cohort of 178 newly diagnoses IPF patients. All patients were treatment naïve at the baseline visit. Blood samples and clinical data were collected from baseline, six months, and 12 months visit. The biomarkers were measured by competitive ELISA using monoclonal antibodies.

Results

Patients with progressive disease had higher (P = 0.0099) serum levels of PRO-C6 compared to those with stable disease over 12 months with an average difference across all timepoints of 12% (95% CI 3–22), whereas C6M levels tended (P = 0.061) to be higher in patients with progressive disease compared with stable patients over 12 months with an average difference across all timepoints of 12% (95% CI − 0.005–27). Patients who did not receive antifibrotic medicine had a greater increase of C6M (P = 0.043) compared to treated patients from baseline over 12 months with an average difference across all timepoints of 12% (95% CI − 0.07–47). There were no differences in biomarker levels between patients receiving pirfenidone or nintedanib.

Conclusions

Type VI collagen formation was related to progressive disease in patients with IPF in a real-world cohort and antifibrotic therapy seemed to affect the degradation of type VI collagen. Type VI collagen formation and degradation products might be potential biomarkers for disease progression in IPF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01684-3.

High turnover of types III and VI collagen in progressive idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

Prediction of idiopathic pulmonary fibrosis (IPF) progression is vital for the choice and timing of treatment and patient follow-up. This could potentially be achieved by prognostic blood biomarkers of extracellular matrix (ECM) remodelling.

METHODS

Neoepitope biomarkers of types III and VI collagen turnover (C3M, C6M, PRO-C3 and PRO-C6) were measured in 185 patients with newly diagnosed IPF. Disease severity at baseline and progression over 6 months was assessed by lung function tests and 6-min walk tests. All-cause mortality was assessed over a 3-year follow-up period.

RESULTS

High baseline levels of C3M, C6M, PRO-C3 and PRO-C6 were associated with more advanced disease at the time of diagnosis. Baseline levels of C6M and PRO-C3 were also associated with mortality over 3 years of follow-up (hazard ratio [HR]: 2.3, 95% CI: 1.3-3.9, p = 0.002 and HR: 1.8, 95% CI: 1.1-3.0, p = 0.03). Patients with several increased biomarkers at baseline, representing a high ECM remodelling phenotype, had more advanced disease at baseline, higher risk of progression or death at 6 months (OR: 1.4, 95% CI: 1.1-1.8, p = 0.002) and higher mortality over 3 years of follow-up (HR: 2.4, 95% CI: 1.3-4.5, p = 0.007).

CONCLUSION

Blood biomarkers of types III and VI collagen turnover, assessed at the time of diagnosis, are associated with several indices of disease severity, short-term progression and long-term mortality. These biomarkers can help to identify patients with a high ECM remodelling phenotype at high risk of disease progression and death.

Increased respiratory morbidity in individuals with interstitial lung abnormalities

Background

Interstitial lung abnormalities (ILA) are common in participants of lung cancer screening trials and broad population-based cohorts. They are associated with increased mortality, but less is known about disease specific morbidity and healthcare utilisation in individuals with ILA.

Methods

We included all participants from the screening arm of the Danish Lung Cancer Screening Trial with available baseline CT scan data (n = 1990) in this cohort study. The baseline scan was scored for the presence of ILA and patients were followed for up to 12 years. Data about all hospital admissions, primary healthcare visits and medicine prescriptions were collected from the Danish National Health Registries and used to determine the participants’ disease specific morbidity and healthcare utilisation using Cox proportional hazards models.

Results

The 332 (16.7%) participants with ILA were more likely to be diagnosed with one of several respiratory diseases, including interstitial lung disease (HR: 4.9, 95% CI: 1.8–13.3, p = 0.008), COPD (HR: 1.7, 95% CI: 1.2–2.3, p = 0.01), pneumonia (HR: 2.0, 95% CI: 1.4–2.7, p <  0.001), lung cancer (HR: 2.7, 95% CI: 1.8–4.0, p <  0.001) and respiratory failure (HR: 1.8, 95% CI: 1.1–3.0, p = 0.03) compared with participants without ILA. These findings were confirmed by increased hospital admission rates with these diagnoses and more frequent prescriptions for inhalation medicine and antibiotics in participants with ILA.

Conclusions

Individuals with ILA are more likely to receive a diagnosis and treatment for several respiratory diseases, including interstitial lung disease, COPD, pneumonia, lung cancer and respiratory failure during long-term follow-up.

Rituximab-induced interstitial lung disease: five case reports

Rituximab (RTX), a mouse/human chimeric anti-CD20 IgG1 monoclonal antibody has been effectively used as a single agent or in combination with chemotherapy regimen to treat lymphoma since 1997. In addition, it has been used to treat idiopathic thrombocytopenic purpura, systemic lupus erythematous, rheumatoid arthritis, and autoimmune hemolytic anemia. Recently, RTX has also been suggested for the treatment of certain connective tissue disease–related interstitial lung diseases (ILD) and hypersensitivity pneumonitis. Rare but serious pulmonary adverse reactions are reported. To raise awareness about this serious side effect of RTX treatment, as the indication for its use increases with time, we report five cases of probable RTX-ILD and discuss the current literature on this potentially lethal association.

Correlation Between Emphysema and Lung Function in Healthy Smokers and Smokers With COPD

Background: Emphysema is an important component of COPD; however, in previous studies of the correlation between airflow limitation (AFL) and computed tomography (CT) lung density as a surrogate for emphysema has varied. We hypothesised a good correlation between lung function (forced expiratory volume in first second [FEV₁]) and emphysema (15^th percentile density [PD15]) and that this correlation also exists between loss of lung tissue and decline in lung function even within the time frame of longitudinal studies of relatively short duration. Methods: We combined 2 large longitudinal studies (the Danish Lung Cancer Screening Trial [DLCST] and the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints [ECLIPSE]) of smokers or former smokers, with a wide range of AFL and CT lung density, and analysed data from 2148 participants who did not change smoking habits and who had at least 2 CT scans and 2 FEV₁ measurements at least 3 years apart. Results: Baseline correlation between FEV₁ and PD15 was high (r=0.716, 95% confidence interval [CI]: 0.694-0.736, p<0.001) indicating that at least half of the variation in FEV₁ can be explained by variation in CT lung density. Correlation between the decline in FEV₁ and progression of PD15 was considerably weaker (r= 0.081, 95% CI: 0.038-0.122, p<0.001). Conclusions: Correlation is very high between lung density and lung function in a broad spectrum of smokers and ex-smokers. In contrast, the temporal associations (slopes) are weakly correlated, probably due to uncertainty in the estimation of slopes within a time frame of 3-4 years.

Emphysema progression is visually detectable in low-dose CT in continuous but not in former smokers

OBJECTIVES

To evaluate interobserver agreement and time-trend in chest CT assessment of emphysema, airways, and interstitial abnormalities in a lung cancer screening cohort.

METHODS

Visual assessment of baseline and fifth-year examination of 1990 participants was performed independently by two observers. Results were standardised by means of an electronic score sheet; kappa and time-trend analyses were performed.

RESULTS

Interobserver agreement was substantial in early emphysema diagnosis; highly significant (p < 0.001) time-trends in both emphysema presence and grading were found (higher prevalence and grade of emphysema in late CT examinations). Significant progression in emphysema was seen in continuous smokers, but not in former smokers. Agreement on centrilobular emphysema subtype was substantial; agreement on paraseptal subtype, moderate. Agreement on panlobular and mixed subtypes was only fair. Agreement was fair regarding airway analysis. Interstitial abnormalities were infrequent in the cohort, and agreement on these was fair to moderate. A highly significant time-trend was found regarding interstitial abnormalities, which were more frequent in late examinations.

CONCLUSIONS

Visual scoring of chest CT is able to characterise the presence, pattern, and progression of early emphysema. Continuous smokers progress; former smokers do not.

KEY POINTS

• Substantial interobserver consistency in determining early-stage emphysema in low-dose CT. • Longitudinal analyses show clear time-trends for emphysema presence and grading. • For continuous smokers, progression of emphysema was seen in all lung zones. • For former smokers, progression of emphysema was undetectable by visual assessment. • Onset and progression of interstitial abnormalities are visually detectable.

Profuse coarse pulmonary nodules in a patient with lymphangioleiomyomatosis: thirty-three years of follow-up

Lymphangioleiomyomatosis (LAM) is a rare disease characterized by progressive cystic destruction of the lungs. We present an unusual radiological presentation of lymphangioleiomyomatosis in a patient followed for 33 years with profuse coarse lung nodules in addition to the classical cystic lesions. We believe that this report might support the case for considering LAM a low-malignant neoplasm.

Analysis of FEV1 decline in relatively healthy heavy smokers: implications of expressing changes in FEV1 in relative terms

Progressive decline in lung function has been widely accepted as the hallmark of chronic obstructive pulmonary disease (COPD); however, recent evidence indicates that the rate of decline measured as decline in forced expiratory volume in one second (FEV1) is higher in mild to moderate COPD than in severe COPD. Usually changes in FEV1 are measured in ml that is "absolute"; however, changes can also be measured "relative" as a percentage of the actual FEV1. We hypothesize that relative measurements could be more appropriate than absolute measurements for describing changes in lung function. We analyzed data from 3,218 relatively healthy heavy smokers who participated in the Danish Lung Cancer Screening Trial. The influences of age, sex, height, body mass index, smoking, and severity of airflow limitation on FEV1 were analyzed in mixed effects models. In absolute terms those with the best lung function consistently showed the steepest decline, whereas in relative terms most fast decliners are found among those with low lung function. Measuring changes in relative terms implied statistically significant acceleration of decline with advancing age, smoking (pack-years) and severity of airflow limitation. Relative measurements may lead to a better understanding of changes in lung function. Smoking and severity of airflow limitation speed up the loss of lung function, and this emphasizes the importance of abstaining from smoking the sooner the better. Measuring changes in relative terms could have important implications for the interpretation of results from clinical trials where FEV1 is the primary outcome. DLCST; www.ClinicalTrials.org , registration number: NCT00496977.

Factors influencing the decline in lung density in a Danish lung cancer screening cohort

Lung cancer screening trials provide an opportunity to study the natural history of emphysema by using computed tomography (CT) lung density as a surrogate parameter. In the Danish Lung Cancer Screening Trial, 2,052 participants were included. At screening rounds, smoking habits were recorded and spirometry was performed. CT lung density was measured as the volume-adjusted 15th percentile density (PD15). A mixed effects model was used with former smoking males with <30 pack-yrs and without airflow obstruction (AFO) at entry as a reference group. At study entry, 893 (44%) participants had AFO. For the reference group, PD15 was 72.6 g·L(-1) with an annual decline of -0.33 g·L(-1). Female sex and current smoking increased PD15 at baseline, 17.3 g·L(-1) (p<0.001) and 10 g·L(-1) (p<0.001), respectively; and both increased the annual decline in PD15 (female: -0.3 g·L(-1); current smoking: -0.4 g·L(-1)). The presence and severity of AFO was a strong predictor of low PD15 at baseline (Global Initiative for Chronic Obstructive Lung Disease (GOLD) I: -1.4 g·L(-1); GOLD II: -6.3 g·L(-1); GOLD III: -17 g·L(-1)) and of increased annual decline in PD15 (GOLD I: -0.2 g·L(-1); GOLD II: -0.5 g·L(-1); GOLD III: -0.5 g·L(-1)). Female sex, active smoking and the presence of AFO are associated with accelerated decline in lung density.

Identification of patients with chronic obstructive pulmonary disease (COPD) by measurement of plasma biomarkers

INTRODUCTION

Inflammation is an important constituent of the pathology of chronic obstructive pulmonary disease (COPD), leading to alveolar destruction and airway remodelling.

OBJECTIVE

The aim of this study was to assess the difference in plasma biomarkers of inflammation between asymptomatic smokers and patients with COPD.

METHODS

We used commercially available enzyme-linked immunosorbent assay kits to measure the plasma levels of tumour necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8), matrix metalloproteinase-9 (MMP-9), monocyte chemotactic protein-1 (MCP-1), tissue inhibitor of metalloproteinase-1 (TIMP-1) and tissue inhibitor of metalloproteinase-2 (TIMP-2) on two occasions with a 2-week interval in patients with COPD (n = 20), asymptomatic smokers (n = 10) and healthy lifelong non-smokers (n = 10). The participants were characterised clinically, physiologically and by quantitative computed tomography by measuring the relative area of emphysema below -910 Hounsfield units (RA-910).

RESULTS

The results of the biomarker measurements on the two occasions were highly reproducible. Patients with COPD had significantly higher plasma levels of IL-8 (P = 0.004) and significantly lower levels of TIMP-1 (P = 0.02) than smokers and non-smokers. There was no statistically significant difference between the three groups in the level of TNF-alpha, MMP-9, MCP-1 and TIMP-2. The IL-8/TIMP-1 ratio correlated significantly with the degree of airway obstruction measured as forced expiratory volume in 1 second (FEV(1)) % predicted (r = -0.47, P < 0.01); with the diffusion capacity (r = -0.41, P < 0.01); and with the grade of emphysema measured as RA-910 (r = 0.39, P = 0.01).

CONCLUSION

These findings suggest that the measurement of plasma biomarkers, such as IL-8/TIMP-1, may aid to discriminate patients with COPD from smokers at lower risk of developing COPD.

Quantitative analysis of pulmonary emphysema using local binary patterns

We aim at improving quantitative measures of emphysema in computed tomography (CT) images of the lungs. Current standard measures, such as the relative area of emphysema (RA), rely on a single intensity threshold on individual pixels, thus ignoring any interrelations between pixels. Texture analysis allows for a much richer representation that also takes the local structure around pixels into account. This paper presents a texture classification-based system for emphysema quantification in CT images. Measures of emphysema severity are obtained by fusing pixel posterior probabilities output by a classifier. Local binary patterns (LBP) are used as texture features, and joint LBP and intensity histograms are used for characterizing regions of interest (ROIs). Classification is then performed using a k nearest neighbor classifier with a histogram dissimilarity measure as distance. A 95.2% classification accuracy was achieved on a set of 168 manually annotated ROIs, comprising the three classes: normal tissue, centrilobular emphysema, and paraseptal emphysema. The measured emphysema severity was in good agreement with a pulmonary function test (PFT) achieving correlation coefficients of up to |r| = 0.79 in 39 subjects. The results were compared to RA and to a Gaussian filter bank, and the texture-based measures correlated significantly better with PFT than did RA.

The effect of inhaled corticosteroids on the development of emphysema in smokers assessed by annual computed tomography

The objective was to evaluate the effect of inhaled corticosteroids on disease progression in smokers with moderate to severe chronic obstructive pulmonary disease (COPD), as assessed by annual computed tomography (CT) using lung density (LD) measurements. Two hundred and fifty-four current smokers with COPD were randomised to treatment with either an inhaled corticosteroids (ICS), budesonide 400 microg bid, or placebo. COPD was defined as FEV(1) < or = 70% pred, FEV(1)/FVC < or = 60% and no reversibility to beta(2)-agonists and oral corticosteroids. The patients were followed for 2-4 years with biannual spirometry and annual CT and comprehensive lung function tests (LFT). CT images were analysed using Pulmo-CMS software. LD was derived from a pixel-density histogram of the whole lung as the 15th percentile density (PD15) and the relative area of emphysema at a threshold of -910 Hounsfield units (RA-910), and both were volume-adjusted to predicted total lung capacity. At baseline, mean age was 64 years and 64 years; mean number of pack-years was 56 and 56; mean FEV(1) was 1.53 L (51% pred) and 1.53 L (53% pred); mean PD15 was 103 g/L and 104 g/L; and mean RA-910 was 14% and 13%, respectively, for the budesonide and placebo groups. The annual fall in PD15 was -1.12 g/L in the budesonide group and -1.81 g/L in the placebo group (p = 0.09); the annual increase in RA-910 was 0.4% in the budesonide group and 1.1% in the placebo group (p = 0.02). There was no difference in annual decline in FEV(1) between ICS (-54 mL) and placebo (-56 mL) (p = 0.89). Long-term budesonide inhalation shows a non-significant trend towards reducing the progression of emphysema as determined by the CT-derived 15th percentile lung density from annual CT scans in current smokers with moderate to severe COPD.

Imaging in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is divided into pulmonary emphysema and chronic bronchitis (CB). Emphysema is defined patho-anatomically as "permanent enlargement of airspaces distal to the terminal bronchiole, accompanied by the destruction of their walls, and without obvious fibrosis" (1). These lesions are readily identified and quantitated using computed tomography (CT), whereas the accompanying hyperinflation is best detected on plain chest X-ray, especially in advanced disease. The diagnosis of CB is clinical and relies on the presence of productive cough for 3 months in 2 or more successive years. The pathological changes of mucosal inflammation and bronchial wall thickening have been more difficult to identify with available imaging techniques. However, recent studies using Multi-detector row CT (MDCT) reported more reproducible assessment of air wall thickening.

Exploring the role of CT densitometry: a randomised study of augmentation therapy in alpha1-antitrypsin deficiency

Assessment of emphysema-modifying therapy is difficult, but newer outcome measures offer advantages over traditional methods. The EXAcerbations and Computed Tomography scan as Lung End-points (EXACTLE) trial explored the use of computed tomography (CT) densitometry and exacerbations for the assessment of the therapeutic effect of augmentation therapy in subjects with alpha(1)-antitrypsin (alpha(1)-AT) deficiency. In total, 77 subjects (protease inhibitor type Z) were randomised to weekly infusions of 60 mg x kg(-1) human alpha(1)-AT (Prolastin) or placebo for 2-2.5 yrs. The primary end-point was change in CT lung density, and an exploratory approach was adopted to identify optimal methodology, including two methods of adjustment for lung volume variability and two statistical approaches. Other end-points were exacerbations, health status and physiological indices. CT was more sensitive than other measures of emphysema progression, and the changes in CT and forced expiratory volume in 1 s were correlated. All methods of densitometric analysis concordantly showed a trend suggestive of treatment benefit (p-values for Prolastin versus placebo ranged 0.049-0.084). Exacerbation frequency was unaltered by treatment, but a reduction in exacerbation severity was observed. In patients with alpha(1)-AT deficiency, CT is a more sensitive outcome measure of emphysema-modifying therapy than physiology and health status, and demonstrates a trend of treatment benefit from alpha(1)-AT augmentation.

Assessment of regional progression of pulmonary emphysema with CT densitometry

BACKGROUND

Lung densitometry is an effective method to assess overall progression of emphysema, but generally the location of the progression is not estimated. We hypothesized that progression of emphysema is the result of extension from affected areas toward less affected areas in the lung. To test this hypothesis, a method was developed to assess emphysema severity at different levels in the lungs in order to estimate regional changes.

METHODS

Fifty subjects with emphysema due to alpha(1)-antitrypsin deficiency (AATD) [AATD deficiency of phenotype PiZZ (PiZ) group] and 16 subjects with general emphysema (general emphysema without phenotype PiZZ [non-PiZ] group) were scanned with CT at baseline and after 30 months. Densitometry was performed in 12 axial partitions of equal volumes. To indicate predominant location, craniocaudal locality was defined as the slope in the plot of densities against partitions. Regional progression of emphysema was calculated after volume correction, and its slope identifies the area of predominant progression. The hypothesis was tested by investigating the correlation between predominant location and predominant progression.

RESULTS

As expected, the PiZ patients showed more basal emphysema than the non-PiZ group (craniocaudal locality, - 40.0 g/L vs - 6.2 g/L). Overall progression rate in PiZ patients was lower than in non-PiZ subjects. A significant correlation was found between craniocaudal locality and progression slope in PiZ subjects (R = 0.566, p < 0.001). In the non-PiZ group, no correlation was found.

CONCLUSIONS

In the PiZ group, the more emphysema is distributed basally, the more progression was found in the basal area. This finding suggests that emphysema due to AATD spreads out from affected areas.

Progression parameters for emphysema: A clinical investigation

In patients with airflow limitation caused by cigarette smoking, lung density measured by computed tomography is strongly correlated with quantitative pathology scores of emphysema, but the ability of lung densitometry to detect progression of emphysema is disputed. We assessed the sensitivity of lung densitometry as a parameter of disease progression of emphysema in comparison to FEV(1) and gas transfer. At study baseline and after 30 months we measured computed tomography (CT)-derived lung density, spirometry and carbon monoxide diffusion coefficient in 144 patients with chronic obstructive pulmonary disease (COPD) in five different centers. Annual change in lung density was 1.31 g/L/year (CI 95%: -2.12 to -0.50 HU, p=0.0015, 39.5 mL/year (CI 95%: -100.0-21.0 mL, p=0.2) for FEV(1) (-39.5 mL) and 24.3 micromol/min/kPa/L/year for gas transfer (CI 95%: -61.0-12.5 micromol/min/kPa/L/year, p=0.2). Signal-to-noise ratio (mean change divided by standard error of the change) for the detection of annual change was 3.2 for lung densitometry, but 1.3 for both FEV(1) and gas diffusion. We conclude that detection of progression of emphysema was found to be 2.5-fold more sensitive using lung densitometry than by using currently recommended lung function parameters. Our results support CT scan as an efficacious test for novel drugs for emphysema.

Quantitative assessment of regional emphysema distribution in patients with chronic obstructive pulmonary disease (COPD)

PURPOSE

To compare objective and subjective assessment of the distribution of emphysema in unselected patients with chronic obstructive pulmonary disease (COPD).

MATERIAL AND METHODS

167 patients were computed tomography (CT) scanned, and the relative area (RA-910) of emphysema in each CT slice was plotted against table position. The craniocaudal distribution was calculated as the slope of the regression line, and grouped as upper-lung-zone predominance (ULP), lower-lung-zone predominance (LLP), or mild/homogeneous distribution (MHE). CT scans were also classified as ULP, LLP, and MHE based on visual assessment of three high-resolution CT (HRCT) slices, and the leading pattern of emphysema was classified as centrilobular (CLE), paraseptal (PSE), panlobular (PLE), or no emphysema (NE).

RESULTS

By objective classification, scans were divided into almost equal numbers of ULP, LLP, and MHE, whereas visual evaluation classified more scans as ULP (P<0.001) and very few as LLP (P<0.0001). In patients with CLE, 49% had ULP by objective classification, whereas LLP was the commonest leading pattern in PSE, PLE, and NE.

CONCLUSION

We found significant discrepancies between the objective and subjective distributions of emphysema in various morphological patterns, which may be of clinical importance in, for instance, lung-volume-reduction surgery.

Variability in densitometric assessment of pulmonary emphysema with computed tomography

OBJECTIVES

The objectives of this study were to investigate whether computed tomography (CT) densitometry can be applied consistently in different centers; and to evaluate the reproducibility of densitometric quantification of emphysema by assessment of different sources of variation, ie, intersite, interscan and inter- and intraobserver variability, in comparison with intersubject variability.

MATERIALS AND METHODS

In 5 different hospitals, 119 patients with emphysema were scanned using standardized protocols. In each site, an observer performed a quantitative densitometric analysis (including blood recalibration) on the corresponding patient group (n=23-25) and one observer analyzed the entire group of 119 patients. After several months, the latter observer analyzed all data for a second time. Subsequently, different sources of variation were assessed by variance component analysis with and without volume correction of the data.

RESULTS

Inter- and intraobserver variability marginally contributes to the total variability (<0.001%). The interscan variability was 0.02% of the total variation after application of volume correction. The intersite variability was 48% as a result of one deviating CT scanner. Air recalibration normalized deviating air densities in CT scanners. Within sites, the intersubject variability ranged between 93% and 99% based on the analysis of 2 subsequent CT scans of the patients.

CONCLUSIONS

Almost all variability in the density measurement of emphysema originates from differences between scanners and from differences in severity of emphysema between patients. Lung densitometry with multislice CT scanners is a highly reproducible measurement, especially if corrected for lung volume, because this reduces interscan variability.

Quantitative assessment of emphysema distribution in smokers and patients with α1-antitrypsin deficiency

INTRODUCTION

Identification of upper lobe emphysema is mandatory before lung volume reduction surgery (LVRS). Here we introduce a CT-based objective model for describing the distribution of different types of emphysema.

METHODS

Fifty COPD patients were included in the study. Half had alpha1-antitrypsin deficiency (alpha1-COPD) and the rest had smoking-induced emphysema (usual COPD). All patients were scanned 3 times. The relative area of emphysema in each CT slice was plotted against table position, and the cranio-caudal distribution was calculated as the slope of the regression line.

RESULTS

The variation in slopes within a patient was much less than the variation in slopes between patients (P<0.0001). There was a significant difference between slopes in the alpha1-COPD and the usual COPD groups (P<0.0001). In the alpha1-COPD group, 24/25 patients had lower lobe emphysema. In the usual COPD group, 4 patients had upper lope predominance, 5 patients had heterogeneous distributions, and 16 patients had lower lobe predominance.

CONCLUSIONS

The majority of patients with smoking-related emphysema have a homogeneous distribution and lower lobe predominance although not as noticeable as in alpha1-antitrypsin deficiency. An objective and quantitative method for determining the distribution of emphysema should be applied when selecting candidates for LVRS.

Quantitative computed tomography and aerosol morphometry in COPD and alpha1-antitrypsin deficiency

Relative area of emphysema below -910 Hounsfield units (RA-910) and 15th percentile density (PD15) are quantitative computed tomography (CT) parameters used in the diagnosis of emphysema. New concepts for noninvasive diagnosis of emphysema are aerosol-derived airway morphometry, which measures effective airspace dimensions (EAD) and aerosol bolus dispersion (ABD). Quantitative CT, ABD and EAD were compared in 20 smokers with chronic obstructive pulmonary disease (COPD) and 22 patients with alpha1-antitrypsin deficiency (AAD) with a similar degree of airway obstruction and reduced diffusion capacity. In both groups, there was a significant correlation between RA-910 and PD15 and pulmonary function tests (PFTs). A significant correlation was also found between EAD, RA-910 and PD15 in the study population as a whole. Upon separation into two groups, the significance disappeared for the smokers with COPD and strengthened for those with AAD, where EAD correlated significantly with RA-910 and PD15. ABD was similar in the two groups and did not correlate with PFT and quantitative CT in either group. In conclusion, based on quantitative computed tomography and aerosol-derived airway morphometry, emphysema was significantly more severe in patients with alpha1-antitrypsin deficiency compared with patients with usual emphysema, despite similar measures of pulmonary function tests.

Alpha1-antitrypsin deficiency. 7: Computed tomographic imaging in alpha1-antitrypsin deficiency

Computed tomographic scanning may replace lung function tests as the golden standard for assessing the response to known and novel treatments for alpha1-antitrypsin deficiency.

Short-term reproducibility of computed tomography-based lung density measurements in alpha-1 antitrypsin deficiency and smokers with emphysema

PURPOSE

To study the short-term reproducibility of lung density measurements by multi-slice computed tomography (CT) using three different radiation doses and three reconstruction algorithms.

MATERIAL AND METHODS

Twenty-five patients with smoker's emphysema and 25 patients with alpha1-antitrypsin deficiency underwent 3 scans at 2-week intervals. Low-dose protocol was applied, and images were reconstructed with bone, detail, and soft algorithms. Total lung volume (TLV), 15th percentile density (PD-15), and relative area at -910 Hounsfield units (RA-910) were obtained from the images using Pulmo-CMS software. Reproducibility of PD-15 and RA-910 and the influence of radiation dose, reconstruction algorithm, and type of emphysema were then analysed.

RESULTS

The overall coefficient of variation of volume adjusted PD-15 for all combinations of radiation dose and reconstruction algorithm was 3.7%. The overall standard deviation of volume-adjusted RA-910 was 1.7% (corresponding to a coefficient of variation of 6.8%). Radiation dose, reconstruction algorithm, and type of emphysema had no significant influence on the reproducibility of PD-15 and RA-910. However, bone algorithm and very low radiation dose result in overestimation of the extent of emphysema.

CONCLUSION

Lung density measurement by CT is a sensitive marker for quantitating both subtypes of emphysema. A CT-protocol with radiation dose down to 16 mAs and soft or detail reconstruction algorithm is recommended.

Volume adjustment of lung density by computed tomography scans in patients with emphysema

PURPOSE

To determine how to adjust lung density measurements for the volume of the lung calculated from computed tomography (CT) scans in patients with emphysema.

MATERIAL AND METHODS

Fifty patients with emphysema underwent 3 CT scans at 2-week intervals. The scans were analyzed with a software package that detected the lung in contiguous images and subsequently generated a histogram of the pixel attenuation values. The total lung volume (TLV), lung weight, percentile density (PD), and relative area of emphysema (RA) were calculated from this histogram. RA and PD are commonly applied measures of pulmonary emphysema derived from CT scans. These parameters are markedly influenced by changes in the level of inspiration. The variability of lung density due to within-subject variation in TLV was explored by plotting TLV against PD and RA.

RESULTS

The coefficients for volume adjustment for PD were relatively stable over a wide range from the 10th to the 80th percentile, whereas for RA the coefficients showed large variability especially in the lower range, which is the most relevant for quantitation of pulmonary emphysema.

CONCLUSION

Volume adjustment is mandatory in repeated CT densitometry and is more robust for PD than for RA. Therefore, PD seems more suitable for monitoring the progression of emphysema.