Roentgenographic underestimation of early asbestosis by International Labor Organization classification. Analysis of data and probabilities

Farewell to an old friend: chest X-ray vs high-resolution computed tomography in welders' lung disease

INTRODUCTION

Welder's lung disease originated from a mixed exposure to different kinds of metals and chemicals from welding fumes. Because of these various harmful effects, irreversible morphological changes may occur in all parts of the respiratory tract, airways and lung parenchyma. Parenchymal changes are the main lesions that define the severity of exposure. The grade of these lesions is the main criteria for compensation claims and the clinical threshold for the occupational health physician's decision making of work change in order to protect the worker's health. In this study, our aim was to compare the diagnostic performance of chest X-ray (CXR) and high-resolution computed tomography (HRCT) for welders' lung disease.

OBJECTIVES

Seventy-four male welders aged between 25 and 55 years were enrolled to this study.

METHODS

Clinical diagnoses were compared by CXR and HRCT. Same radiologists evaluated the scans without any knowledge about the medical history of the patient (double-blinded evaluation). The agreement between radiologists was compared with Cohen's kappa statistics.

RESULTS

The mean age for 74 welders was 40.7 years. The mean duration of exposure was 18.9 years. Although all were found to be nonpathological on the CXR, 27 mild nodular and nine mild linear opacities, five emphysematous changes, three ground glass infiltrates and one pleural thickening were detected by HRCT.

CONCLUSIONS

HRCT provides better diagnostic performance compared to CXR for the diagnosis of welders' lung disease.

Antemortem diagnosis of asbestosis by screening chest radiograph correlated with postmortem histologic features of asbestosis: a study of 273 cases

BACKGROUND

Accuracy in the clinical diagnosis of asbestosis has significant implications for the future health of affected patients as well as serious medicolegal implications for both patients and asbestos-associated industries. The radiographic gold-standard for diagnosis of asbestosis has been the plain chest radiograph, and in many asbestosis-screening clinics, chest radiograph abnormalities in conjunction with a history of asbestos exposure have been the mainstay of diagnosis. No studies have yet compared the antemortem chest radiographic diagnosis of asbestosis with the subsequent presence of pulmonary fibrosis and lung tissue ferruginous bodies at autopsy.

METHODS

Records were reviewed from 273 autopsies performed to investigate asbestosis over an 11-year period. Accrued data included age and gender as well as the presence or absence of the following: occupational exposure to asbestos, antemortem clinical diagnosis of asbestosis by chest radiograph, fibrous pleural plaques, peribronchiolar or interstitial pulmonary fibrosis, ferruginous bodies in histologic sections of lung tissue, and ferruginous bodies in digested lung tissue.

RESULTS

242 cases with the antemortem radiographic diagnosis of asbestosis (study group) were identified. 31 additional autopsies had been requested based on history of asbestos exposure without radiographic documentation of asbestosis (control group). Comparison of the two groups showed a statistically significant increase in the association of chest radiograph-diagnosed asbestosis and the presence at autopsy of pleural plaques (p = 0.0109), peribronchiolar or interstitial pulmonary fibrosis (p = 0.0472), and histologically-diagnostic asbestosis (p = 0.0021). At autopsy, histologically-diagnostic asbestosis was confirmed in only 90 of the 243 study group cases. Comparison of individual parameters within the 242 study group cases showed a statistically significant correlation between the presence of fibrous pleural plaques and histologically-proven pulmonary fibrosis (p = 0.0025) as well as the subsequent histologic diagnosis of asbestosis (p < 0.0001).

CONCLUSION

Clinical diagnosis of asbestosis by screening chest radiograph is more predictive of the postmortem presence of fibrous pleural plaques, pulmonary fibrosis, and histologically-proven asbestosis than is occupational exposure history alone. However, chest radiograph-based diagnosis of asbestosis significantly overpredicts the subsequent histologic diagnosis of asbestosis.

Comparison of chest radiography and high-resolution computed tomography findings in early and low-grade coal worker’s pneumoconiosis

INTRODUCTION

High-resolution computed tomography (HRCT) is more sensitive than chest X-ray (CXR) in the depiction of parenchymal abnormalities. We aimed to present and compare CXR and HRCT findings in coal workers with and without early and low-grade coal worker's pneumoconiosis (CWP).

MATERIALS AND METHODS

71 coal workers were enrolled in this study. All workers were male. The CXR and HRCT of those workers were obtained and graded by two trained readers. HRCT's were graded according to Hosoda and Shida's Japanese classification. After grading, 67 workers with CXR profusion 0/0-2/2 were included in the study. Four patients with major opacity were excluded. Profusion 0/1 to 1/1 cases were accepted as early and profusion 1/2 and 2/2 cases as low-grade pneumoconiosis.

RESULTS

Discordance between CXR and HRCT was high. Discordance rate was found higher in the early pneumoconiosis cases with negative CXR than low-grade pneumoconiosis (60, 36 and 8%, respectively). When coal miners with normal CXR were evaluated by HRCT, six out of 10 cases were diagnosed as positive. In low-grade pneumoconiosis group, the number of patients with positive CXR but negative HRCT were low in comparison to patients with CXR negative and early pneumoconiosis findings. Most of the CXR category 0 patients (10/16) were diagnosed as category 1 by HRCT. Eleven cases diagnosed as CXR category 1 were diagnosed as category 0 (7/11) and category 2 (4/11) by HRCT. In CXR category 2 (eight cases), there were four cases diagnosed as category 1 by HRCT.

CONCLUSIONS

Discordance between CXR and HRCT was high, especially for CXR negative and early pneumoconiosis cases. The role of CXR in screening coal workers to detect early pneumoconiosis findings should be questioned. We suggest using HRCT as a standard screening method instead of CXR to distinguish between normal and early pneumoconiosis.

Changing patterns in asbestos-induced lung disease

STUDY OBJECTIVES

To determine patterns in asbestos-induced lung diseases found in older, less exposed workers.

DESIGN

Review of a database evaluating lung function, smoking status, form of asbestos-induced lung disease, and radiograph abnormalities.

SETTING

Outpatient clinic.

PARTICIPANTS

A total of 3383 asbestos-exposed workers referred for independent medical evaluation, including control subjects who lacked asbestos-specific radiograph abnormalities (n = 243), subjects with low International Labor Organization (ILO) scores (n = 2,685), high ILO scores (n = 312), bronchogenic cancer (n = 63), and mesothelioma (n = 80). Of these, 3,327 workers have specific smoking status information and 3,312 workers have lung volume measures.

INTERVENTIONS

Chest radiographs were interpreted by a certified B-reader, and abnormalities were quantified according to the ILO scoring system. Spirometry and lung volume measurement were performed. Subjects completed a self-administered questionnaire that was reviewed at the time of examination. Control subjects were screened on two separate occasions at least 10 years apart to exclude subclinical or slowly progressive asbestos-induced lung disease.

MEASUREMENTS AND RESULTS

The mean age of the population was 65.1 +/- 9.9 years, and the latency was 41.4 +/- 10.1 years (+/- SD). Most subjects (41.8%) had normal pulmonary function. Obstruction was the most common pulmonary function abnormality (25.4%), followed by restriction (19.3%) and a mixed pattern (6.0%). Most subjects (79.4%) had low ILO scores. Benign pleural abnormalities were the only findings in 54% of subjects with low ILO score. Subjects with high ILO scores were older, smoked more, and had a longer latency than subjects with low ILO scores and control subjects. Smokers were younger, had a shorter latency, and had paradoxically greater ILO scores than nonsmokers. Subjects with bronchogenic cancer and mesothelioma had longer latencies than control subjects and subjects with benign asbestos-induced lung disease.

CONCLUSIONS

Asbestos-induced lung disease today is characterized by low ILO scores, long latencies, greater disease magnitude in smokers, and a normal or obstructive pattern of pulmonary function abnormality. Spirometric evaluation in the absence of lung volume measurements caused misclassification that resulted in overestimation of the presence of a restrictive pattern of pulmonary function.

Reliability and validity of chest radiograph surveillance programs

STUDY OBJECTIVES

Due to the lack of consensus in the literature in the use of posteroanterior (PA) vs PA with right and left oblique views as the optimum radiograph surveillance methodology to investigate pleural changes, a study was undertaken to evaluate the reliability, sensitivity, and specificity of these two approaches.

DESIGN

Three experienced radiologist B readers used the 1980 International Labor Office classification system for pneumoconiosis to independently read chest radiographs of workers with individual identifiers masked. All radiographs were read first as a PA view only. Unknown to the B readers, each subject's PA was then matched to his or her corresponding right and left oblique views (film triad) and re-read several weeks later.

SETTING AND PARTICIPANTS

The respiratory health of 652 workers exposed to refractory ceramic fiber was assessed as part of cross-sectional and longitudinal surveillance programs.

MEASUREMENTS AND RESULTS

kappa Statistics for interreader and intrareader reliability between the PA view and film triad methods were calculated. Sensitivity, specificity, and positive predictive value were assessed by comparing the initial cross-sectional study to the longitudinal study. The film triad method had considerably higher interreader reliability (kappa = 0.59) compared to the PA-only method (kappa = 0.44). Results from the initial cross-sectional study were then compared to findings evaluated longitudinally. The film triad again was superior, demonstrating a positive predictive value of 73.7% compared to only 47.8% for the PA method.

CONCLUSIONS

It is our recommendation that the film triad method be used in surveillance studies where both parenchymal and pleural changes are anticipated.

Differentiation of the ILO boundary chest roentgenograph (0/1 to 1/0) in asbestosis by high-resolution computed tomography scan, alveolitis, and respiratory impairment

High-resolution computed tomography (HRCT) scans have been advocated as providing greater sensitivity in detecting parenchymal opacities in asbestos-exposed individuals, especially in the presence of pleural fibrosis, and having excellent inter- and intraobserver reader interpretation. We compared the 1980 International Labor Organization (ILO) International Classification of the Radiographs of the Pneumoconioses for asbestosis with the high-resolution CT scan using a grid scoring system to better differentiate normal versus abnormal in the ILO boundary 0/1 to 1/0 chest roentgenograph. We studied 37 asbestos-exposed individuals using the ILO classification, HRCT grid scores, respiratory symptom questionnaires, pulmonary function tests, and bronchoalveolar lavage. We used Pearson correlation coefficients to evaluate the linear relationship between outcome variables and each roentgenographic method. The normal HRCT scan proved to be an excellent predictor of "normality," with pulmonary function values close to 100% for forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), total lung capacity (TLC), and carbon monoxide diffusing capacity (DLCO) and no increase in BAL inflammatory cells. Concordant HRCT/ILO abnormalities were associated with reduced FEV1/FVC ratio, reduced diffusing capacity, and alveolitis consistent with a definition of asbestosis. In our study, the ILO classification and HRCT grid scores were both excellent modalities for the assessment of asbestosis and its association with impaired physiology and alveolitis, with their combined use providing statistical associations with alveolitis and reduced diffusing capacity.

High-resolution computed tomography of the lungs in coal miners with a normal chest radiograph

Nowadays, there is a tendency to carry out high-resolution computed tomography (HCRT) in diagnosis of interstitial disease in former coal miners, but the validity and consequences in terms of compensation have not been validated. This study was designed to investigate HRCT outcome (visual and densitometric) and lung function in a group of ex-coal miners with a normal (ILO < or = 0/1) chest radiograph. In more than half of the coal miners HRCT assessed nodules visually, indicative of coal workers' pneumoconiosis (CWP). This finding was strengthened by densitometric data. With increment of cumulative dust exposure a trend was observed toward a higher mean coal workers' pneumoconiosis (MCWP) score and a higher mean lung density value. No relation was observed between the pulmonary function tests and the MCWP score or the mean lung density. In conclusion, visual assessment of HRCT slices is more sensitive than chest radiographs to detect CWP. Application of densitometric analysis to the individual coal miners with early disease seems limited because of the variability in lung density among normals.

Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests

The lungs of 50 symptom free workers exposed to amosite and with normal pulmonary function tests were examined by high resolution computed tomography (HRCT). Twenty five had normal standard chest radiographs whereas the other 25 had radiographs interpreted as near normal (International Labour Office profusion score < 0/1 or suspected pleural plaques). In 13 of the workers the results of HRCT were negative; in 22 pleural plaques were found, in five there was only parenchymal involvement, and 10 had both pleural and parenchymal changes. The mean duration of exposure to amosite was significantly longer for the subjects with parenchymal signs than for those with normal parenchyma and for the workers with pleural plaques than for those with normal pleura and lung parenchyma. The prevalence of identified pleural and parenchymal abnormalities in the 50 workers was also significantly higher than in a reference group without exposure to asbestos. It is concluded that HRCT may detect initial lung and pleural involvement in symptom free workers exposed to amosite and the mean duration of exposure is longer for subjects with parenchymal or pleural involvement.

High-resolution computed tomography in the early detection of asbestosis

A group of 21 former asbestos sprayers was studied with high-resolution computed tomography (HRCT), and the findings were compared with radiographic, exposure and lung function variables. HRCT was superior to plain radiography in detecting parenchymal and pleural changes. It showed changes indicative of lung fibrosis, especially septal lines and parenchymal bands, in 9 of the 12 subjects (75%) with a plain radiographic category of 0/0 in the International Labour Office (ILO) 1980 classification of radiographs of pneumoconioses. The HRCT findings were classified according to a method developed by the authors, and an HRCT parenchymal score was calculated. The HRCT revealed pleural plaques in 19 of the 21 (90%) asbestos sprayers, whereas plain radiography detected pleural plaques in only 5 (24%) sprayers. Changes in the visceral pleura were detected twice as often with HRCT as with plain radiography. In the group without radiographic evidence of lung fibrosis (ILO < 1/0) and without evidence of emphysema in either the radiographs or the HRCT examination, there was a correlation between the HRCT parenchymal score and diffusion capacity (r = -0.64, P = 0.03) and total lung capacity (r = -0.61, P = 0.04). This finding indicates that parenchymal changes seen only with HRCT are of clinical importance. The study strongly suggests that for asbestos-exposed workers with an ILO classification of < 1/0 and functional impairment, an HRCT examination should always be considered.

Computed tomography in the early detection of asbestosis

Computed tomography (CT; both conventional (CCT) and high resolution (HRCT)) scans of the thorax were evaluated to detect early asbestosis in 61 subjects exposed to asbestos dust in Québec for an average of 22(3) years and in five controls. The study was limited to consecutive cases with chest radiographs of the International Labour Organisation categories 0 or 1 determined independently. All subjects had a standard high kilovoltage posteroanterior and lateral chest radiograph, a set of 10-15 1 cm collimation CCT scans and a set of three to five 2 mm collimation HRCT scans in the upper, middle, and lower lung fields. Five experienced readers independently read each chest radiograph and sets of CT scans. On the basis of three to five readers agreeing for small opacities of the lung parenchyma, 12/46 (26%) negative chest radiographs were positive on CT scans, but 6/18 (33%) positive chest radiographs were negative on CT scan. On the basis of four to five readers agreeing on a chest radiograph, 36/66 (54%) subjects were normal (group A), 17/66 (26%) were indeterminate (group B), and 13/66 (20%) were abnormal (group C). By the combined readings of CCT and HRCT, 4/31 (13%) asbestos exposed subjects of group A were abnormal (p < 0.001), 6/17 (35%) of group B were abnormal, and in group C, 1/13 (8%) was normal, 2/13 were indeterminate, and 10/13 (77%) were abnormal. Separate readings of CCT and HRCT on distinct films in 14 subjects showed that all cases of asbestosis were abnormal on both CCT and HRCT. Inter-reader analyses by kappa statistics showed significantly better agreement for the readings of CT than the chest radiographs (p < 0.001), and for the reading of CCT than HRCT (p < 0.01). Thus CT scans of the thorax identifies significantly more irregular opacities consistent with the diagnosis of asbestosis than the chest radiograph (20 cases on CT scans v 13 on chest radiographs when four to five readers agreed, 13% of asbestos exposed subjects with normal chest radiographs or 21% of asbestos exposed subjects with normal or near normal chest radiographs. It decreased the number of indeterminate cases significantly from 17 on chest radiographs to 13 on CT scans. All cases of asbestosis detected only on CT scans were similarly seen on CCT and HRCT and did not have significant changes in lung function. The CT scans significantly reduced the inter-reader variability, despite the absence of ILO type reference films for these scans.

Noninvasive detection of early asbestos-related disease of the thorax: algorithmic analysis of radiographic, nuclear, and serologic tests

Improved imaging techniques may assist in the diagnosis of early asbestosis, such as could occur from "asbestos in place." These include (1) increased visualization of visceral pleural thickening, (2) high-resolution computed tomography (HRCT), and (3) gallium scanning, combined with evidence of serum markers indicating inflammation-associated pulmonary collagen formation. Combining these imaging and serum test observations with a clinically useful algorithmic approach may permit the diagnosis of "early" asbestosis, which is not now possible from the individual test results or from an unweighted combination of such data.

High-resolution computed tomography of asbestos-related diseases

There is growing evidence that HRCT can detect both interstitial and pleural disease in advance of conventional clinical or radiographic studies. Limited HRCT scans are roughly competitive in time and cost with 4-view radiographic examinations. The use of limited HRCT for large-scale screening of asbestos-exposed individuals is controversial. Hopefully this will be resolved as we gain greater understanding of the specificity of HRCT and establish guidelines for standardizing technique and interpretation. At present, limited HRCT scans can supplement the chest radiographic evaluation of subjects in whom there is equivocal parenchymal or pleural disease, unexplained abnormalities on pulmonary function tests, or significant coexisting pleural disease that precludes evaluation of the underlying parenchyma. Interstitial abnormalities on HRCT may be reasonably ascribed to asbestos exposure when there is clear historical documentation of significant, remote dust exposure or concomitant evidence of typical bilateral asbestos-related pleural disease. A subpleural distribution of interstitial abnormality in nondependent lung is important to establish the diagnosis of interstitial fibrosis. Although both unilateral pleural and parenchymal fibroses have been reported, lesions should generally be present bilaterally. In individuals with combined asbestos-cigarette smoke exposure in whom symptoms or functional abnormalities are present, HRCT may play a central role in distinguishing emphysematous lung destruction from the peripheral interstitial changes of asbestosis. Finally, in individuals with significant pleural or parenchymal fibrosis, focal lung masses may not be visible on chest radiographs. In these individuals, CT protocols that sample all regions of the thorax are appropriate.

Rounded atelectasis complicated by obstructive pneumonia and pulmonary arterial thrombosis

A patient with a history of asbestos exposure developed rounded atelectasis. The mass was associated with local bronchial obstruction, obstructive pneumonia and arterial thrombosis. Autopsy demonstrated marked pleural thickening and radiographically inapparent asbestosis. This is the first reported case in which seemingly benign rounded atelectasis not only increased morbidity, but also contributed to mortality through airway obstruction and local arterial thrombosis.

Chest X-rays in hypersensitivity pneumonitis: a metaanalysis of secular trend

A metaanalysis of published reports of outbreaks of hypersensitivity pneumonitis was undertaken. A statistically significant substantial decline was seen in the sensitivity of chest X-rays (percent of positive in cases of disease) for the diagnosis of hypersensitivity pneumonitis over the years 1950-1980. Chest X-rays were also less likely to be abnormal where a population-based approach to the diagnosis of disease had been undertaken. Such declines in the diagnostic "sensitivity" of a test may be related to secular trends in knowledge and recognition of disease or to changes in the disease itself. Standardization of chest X-ray interpretation alone, even if successful, may not resolve the issue of accurate diagnosis of interstitial lung disease.