Assessment of asbestos-induced pleural disease by computed tomography--correlation with chest radiograph and lung function

Chest Imaging in the Diagnosis of Occupational Lung Diseases

Imaging plays a crucial role in the diagnosis and monitoring of occupational lung diseases (OLDs); however, the sensitivity and specificity of detection and diagnosis vary greatly depending on the imaging modality used. There is substantial overlap in appearance with non-occupation-related entities. OLDs should be considered in the differential even in the absence of a provided exposure history. Because many findings are not specific, a multidisciplinary approach is important in arriving at the diagnosis and will continue to be important as workplace-related pulmonary diseases evolve with changing industrial practices and workplace regulations.

Quantification of pleural plaques by computed tomography and correlations with pulmonary function: preliminary study

Background

The aims of this study were to quantify pleural plaque volumes (PPVs) by computed tomography (CT) and investigate relations between PPV and pulmonary function after excluding other factors that might affect pulmonary function.

Methods

Twenty-six subjects with pleural plaques and pulmonary function test (PFT) results among 1,544 subjects that registered with the Korea Environment Corporation for asbestos damage relief from January 2011 to December 2015 were included. Subjects with CT evidence of lung diseases and/or previous surgery were excluded. PPVs were measured by tracing the outlines of all pleural plaques on CT images. Patients were allocated to three groups by PPV, as follows, <10, 10-20, or ≥20 mL, and the PFT results of these groups were analyzed and compared. Simple linear regression analysis and multiple regression analysis were used to evaluate correlations between PPV and PFT variables.

Results

No significant relationship was found between total PPV and pulmonary function indices or between PPV groups and PFT results (P>0.05). However, forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and diffusing capacity of the lung for carbon monoxide (DLCO) values in the higher PPV group (≥20 mL) tended to be lower, indicating a restrictive pattern of pulmonary function.

Conclusions

We quantified PPV on CT and found out higher PPV tended to exhibit a restrictive pattern. However, pleural plaques alone were not found to be significantly associated with pulmonary function.

Novel Logistic Regression Model of Chest CT Attenuation Coefficient Distributions for the Automated Detection of Abnormal (Emphysema or ILD) Versus Normal Lung

RATIONALE AND OBJECTIVES

We evaluated the role of automated quantitative computed tomography (CT) scan interpretation algorithm in detecting interstitial lung disease (ILD) and/or emphysema in a sample of elderly subjects with mild lung disease. We hypothesized that the quantification and distributions of CT attenuation values on lung CT, over a subset of Hounsfield units (HUs) range (-1000 HU, 0 HU), can differentiate early or mild disease from normal lung.

MATERIALS AND METHODS

We compared the results of quantitative spiral rapid end-exhalation (functional residual capacity, FRC) and end-inhalation (total lung capacity, TLC) CT scan analyses of 52 subjects with radiographic evidence of mild fibrotic lung disease to the results of 17 normal subjects. Several CT value distributions were explored, including (1) that from the peripheral lung taken at TLC (with peels at 15 or 65 mm), (2) the ratio of (1) to that from the core of lung, and (3) the ratio of (2) to its FRC counterpart. We developed a fused-lasso logistic regression model that can automatically identify sub-intervals of -1000 HU and 0 HU over which a CT value distribution provides optimal discrimination between abnormal and normal scans.

RESULTS

The fused-lasso logistic regression model based on (2) with 15-mm peel identified the relative frequency of CT values of over -1000 HU and -900 and those over -450 HU and -200 HU as a means of discriminating abnormal versus normal lung, resulting in a zero out-sample false-positive rate, and 15% false-negative rate of that was lowered to 12% by pooling information.

CONCLUSIONS

We demonstrated the potential usefulness of this novel quantitative imaging analysis method in discriminating ILD and/or emphysema from normal lungs.

Medicolegal Aspects of Asbestos II — Benign Pleural and Lung Diseases

A variety of benign lesions affecting the pleura and/or lung can result from inhaling asbestos fibers. Establishing the presence or absence of these entities often plays an important role in the evaluation, presentation and ultimate resolution of asbestos disease litigation. Forensic pathologists may become involved in these cases to address issues of diagnosis, exposure and/or disease attribution. This article reviews medicolegal issues pertaining to benign asbestos-induced diseases of the pleura and lung.

Imaging the pleura

Pleural disease is now recognized as an important subspecialty of pulmonary medicine, with increasing provision being made for specialist services and procedures. In response, the field of pleural imaging has advanced in recent years, especially with regard to ultrasound. Salient multimodality imaging techniques are discussed.

Comparison of chest digital tomosynthesis and chest radiography for detection of asbestos-related pleuropulmonary disease

AIM

To compare chest digital tomosynthesis (DTS) with digital radiography for the detection of asbestos-related pleuropulmonary disease.

MATERIALS AND METHODS

The institutional review board approved this study and all participants gave informed consent. Forty-five participants with a history of asbestos exposure were examined with DTS and radiography. Low-dose multidetector computed tomography (CT) in the prone position served as the reference. Two observers evaluated all images for the presence of pleural abnormalities and asbestosis. Interobserver agreement was analysed by using the k statistic. Diagnostic performance of the two imaging methods was compared using McNemar's test.

RESULTS

Interobserver agreement regarding DTS findings was moderate to very good (k = 0.544-0.846) and superior to the radiographic findings (k = 0.236-1.000). Overall, the diagnostic accuracy of DTS for the lesion detection was significantly better than with radiography (all p < 0.05, except that for the comparison of diagnostic accuracy of DTS versus radiographic detection of left diaphragmatic plaques and asbestosis). DTS was more sensitive than radiography for the detection of asbestosis (82% versus 27%, p = 0.031).

CONCLUSION

DTS is more accurate than radiography in the detection of pleural plaques and more sensitive than radiography in the detection of asbestosis. Interobserver agreements with respect to the DTS findings were superior to the radiographic findings.

[Imaging in occupational lung diseases]

This chapter consists of a review of the literature regarding radiographic and tomographic characteristics of the principal occupational respiratory diseases (silicosis and asbestosis). Special attention is given to the practical relevance of high-resolution computed tomography, which is the most sensitive and specific method of identifying and quantifying the extent of pleural and parenchymal lesions related to such diseases.

Imaging of Pleural Disease

Imaging plays an important role in the diagnosis and subsequent management of patients with pleural disease. The presence of a pleural abnormality is usually suggested following a routine chest x-ray, with a number of imaging modalities available for further characterization. This article describes the radiographic and cross-sectional appearances of pleural diseases, which are commonly encountered in every day practice. The conditions covered include benign and malignant pleural thickening, pleural effusions, empyema and pneumothoraces. The relative merits of CT, MRI and PET in the assessment of these conditions and the role of image-guided intervention are discussed.

Pleural Plaques in Asbestos-exposed Workers: Reproducibility of a New High-resolution CT Visual Semiquantitative Measurement Method

OBJECTIVE

To assess the reproducibility of a new high-resolution computed tomography (CT) visual semiquantitative method for pleural plaques in asbestos-exposed workers.

MATERIAL AND METHODS

We performed thin-section CT in 752 chrysotile asbestos mining workers and ex-workers. Institutional review board approval and signed written informed consent from subjects were obtained. Two readers independently evaluated the 752 CT scans and identified 57 workers (mean age +/- SD, 61.8 years +/- 8.1; range, 37 to 81 years) who had pleural plaques and no other pleural or parenchymal abnormality. Three independent radiologists then quantified the plaque burden in these 57 workers using a scoring system based on the evaluation of the maximum thickness of parietal pleural plaques and percentage of parietal pleural surface involvement. We also calculated the proportion between the number of CT slices with diaphragmatic plaques and the total number of slices in which the diaphragm was seen (pdiaph). The intraobserver and interobserver agreements were analyzed using weighted Kappa coefficient.

RESULTS

Interobserver agreements were good for the pleural plaque score (k = 0.61, 0.75, and 0.79) and ranged from good (k = 0.61) to excellent (k = 0.86) for the pdiaph. Intraobserver agreements ranged from good to excellent for the pleural plaque score (k = 0.79 and 1.00) and for the pdiaph (k = 0.79 and 0.93).

CONCLUSION

The method proposed for high-resolution CT pleural plaque quantification in asbestos-exposed workers has a high reproducibility.

Placas pleurais relacionadas com o asbesto: Revisão da literatura

Pleural plaques (PP) are considered to be hallmarks of asbestos exposure. They constitute focal thickenings of the pleura and are commonly seen in patients without lung disease. They can involve parietal, diaphragmatic and mediastinal pleura. Chest x-ray is frequently used for PP diagnosis, but computed tomography, especially when used the high-resolution technique, is the imaging exam with the greatest sensibility and specificity. PP are almost always asymptomatic, but there are some controversial about their relationship with asbestos exposure indexes, pulmonary functional alterations and risk of neoplasias.

Asbestos-Related Pleural Disease

OBJECTIVES

We sought to compare respiratory-gated high-spatial resolution magnetic resonance imaging (MRI) and radial MRI with ultra-short echo times with computed tomography (CT) in the diagnosis of asbestos-related pleural disease.

METHODS

Twenty-one patients with confirmed long-term asbestos exposure were examined with a CT and a 1.5-T MR unit. High-resolution respiratory-gated T2w turbo-spin-echo (TSE), breath-hold T1w TSE, and contrast-enhanced fat-suppressed breath-hold T1w TSE images with an inplane resolution of less than 1 mm were acquired. To visualize pleural plaques with a short T2* time, a pulse sequence with radial k-space-sampling was used (TE = 0.5 milliseconds) before and after administration of Gd-DTPA. CT and MR images were assessed by 4 readers for the number and calcification of plaques, extension of pleural fibrosis, extrapleural fat, detection of mesothelioma and its infiltration into adjacent tissues, and detection of pleural effusion. Observer agreement was studied with the use of kappa statistics.

RESULTS

The MRI protocol allowed for differentiation between normal pleura and pleura with plaques. Interobserver agreement was comparable for MRI and CT in detecting pleural plaques (median kappa = 0.72 for MRI and 0.73 for CT) and significantly higher with CT than with MRI for detection of plaque calcification (median kappa 0.86 for CT and 0.72 for MRI; P = 0.03). Median sensitivity of MRI was 88% for detection of plaque calcification compared with CT. For assessment of pleural thickening, pleural effusion, and extrapleural fat, interobserver agreement with MRI was significantly higher than with CT (median kappa 0.71 and 0.23 for pleural thickening, 0.87 and 0.62 for pleural effusion, and 0.7 and 0.56 for extrapleural fat, respectively; P < 0.05). For detection of mesothelioma, median kappa was 0.63 for MRI and 0.58 for CT.

CONCLUSION

High-resolution MR sequences and radial MRI achieve a comparable interobserver agreement in detecting pleural plaques and even a higher interobserver agreement in assessing pleural thickening, pleural effusion, and extrapleural fat when compared with CT.

Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques

BACKGROUND

In the literature, the criteria used to define pleural plaques (PP) and diffuse pleural thickening (DPT) are very heterogeneous and often imprecise. A multicenter restropective study was conducted to assess the relevance of two radiographic definitions of DPT.

METHODS

The study population consisted of 287 subjects with asbestos-related pleural thickening. Two definitions were used to characterize DPT on postero-anterior chest radiographs: definition 1: pleural thickening associated with obliteration of the costophrenic angle; definition 2: pleural thickening at least 5 mm wide, extending for more than one quarter of the chest wall. Prevalence of respiratory symptoms and pulmonary function tests were compared in the DPT and PP groups resulting from the two definitions of DPT.

RESULTS

According to definition 1, 34 patients (11.8%) were classified in the DPT group. Prevalence of chronic sputum, dyspnea, and chest pain was significantly higher in this group than in the PP group. FEV(1), FVC, and TLC were significantly lower. The differences persisted after adjustment for confounding factors. According to definition 2,102 patients (36.6%) were classified in the DPT group. DPT and PP groups did not differ in terms of prevalence of respiratory symptoms, or pulmonary function tests. Agreement between readers was significantly better when using definition 1.

CONCLUSIONS

Obliteration of costophrenic angle is a much more reliable sign than dimensional criteria to characterize DPT.

Benign asbestos pleural diseases

The global incidence of asbestos-related lung diseases is expected to continue to rise. Although much attention is devoted to malignant diseases induced by asbestos, benign asbestos pleural diseases (pleural plaques, benign asbestos-related pleural effusion, diffuse pleural thickening, and rounded atelectasis) are common in clinical practice and often produce diagnostic difficulties. The authors describe the clinical features of benign asbestos-related pleural disease, before focusing on recent advances in radiology and on controversies surrounding the pathogenesis of asbestos-induced pleural injury. Advances in computed tomography have assisted the understanding and diagnosis of these diseases, and increasing evidence suggests radiologic appearances on computed tomography can predict impairment in pulmonary function tests. The pathogenesis of asbestos-induced pleural diseases has also been subject to extensive investigation. Asbestos fibers can provoke pleural inflammation from direct toxicity to mesothelial cells. Inhaled asbestos fibers can also elicit pleural injury indirectly via the release of growth factors and inflammatory cytokines from within the lung. Although progress has been made in the understanding of the mechanisms of asbestos pleural injury, many important questions remain unanswered. The role of genetic factors and possible environmental cofactors (eg, simian virus 40) in the pathogenesis of benign asbestos pleural diseases requires further research.

Asbestos: when the dust settles an imaging review of asbestos-related disease

Asbestos-related neoplastic and nonneoplastic diseases of the lungs and pleura range from pleural effusion and pleural plaques to lung cancer and malignant mesothelioma. Pleural effusions are typically hemorrhagic exudates of mixed cellularity but do not typically contain asbestos bodies. The classic distribution of pleural plaques seen on chest radiographs is the posterolateral chest wall between the seventh and tenth ribs, lateral chest wall between the sixth and ninth ribs, the dome of the diaphragm, and the mediastinal pleura. Computed tomographic (CT) findings support this distribution but also show anterior and paravertebral plaques not well shown at chest radiography. Imaging features of diffuse pleural thickening include a continuous sheet, often involving the costophrenic angles and apices, that rarely calcifies. The typical CT features of round atelectasis are of a round or oval mass that abuts the pleura, a "comet tail" of bronchovascular structures going into the mass, and thickening of the adjacent pleura. Features of asbestosis on chest radiographs include ground-glass opacification, small nodular opacities, "shaggy" cardiac silhouette, and ill-defined diaphragmatic contours. CT, however, is more sensitive in their detection. Chest radiography in patients with malignant mesothelioma may show an effusion, pleural thickening, and as the tumor progresses, a more lobulated outline. CT can help identify the disease in its early stages. Asbestos-related cancers can occur anywhere in the lungs. Recognition of the clinical, radiologic, and pathologic features of these diseases will be important for some years to come.

Functional consequences of pleural disease evaluated with chest radiography and CT

PURPOSE

To identify a system for the quantification of pleural thickening with an acceptable level of interobserver variation and good functional correlation in individuals with pleural disease.

MATERIALS AND METHODS

The extent of pleural thickening and plaques was assessed in 50 patients by using the following: (a) a radiographic score based on the International Labour Office system, (b) a subjective simple computed tomographic (CT) score, (c) a subjective comprehensive CT score, (d) an objective nonautomated method, and (e) an objective computer-aided semiautomated method.

RESULTS

Similar correlations between the extent of diffuse pleural thickening and forced vital capacity were seen for each system (objective CT, r = -0.72, P <.001; simple CT, r = -0.69, P <.001; radiographic, r = -0.67, P <.001; comprehensive CT, r = -0.66, P <.001). Comparable correlations were observed for total lung capacity. After controlling for extent of diffuse pleural thickening, pleural plaque scores were functionally irrelevant.

CONCLUSION

Comparable functional-morphologic correlations were achieved by using different CT and radiographic scoring systems for pleural disease. A subjective simple CT system had the advantages of ease of application and potential to aid in the accurate assessment of the lung parenchyma, which may be important in individuals exposed to asbestos.

In defence of the carbon monoxide transfer coefficient Kco (TL/VA)

The carbon monoxide transfer factor (TL,co) is the product of the two primary measurements during breath-holding, the CO transfer coefficient (Kco) and the alveolar volume (VA). Kco is essentially the rate constant for alveolar CO uptake (Krogh's kco), and in healthy subjects, increases when VA is reduced by submaximal inflation, or when pulmonary blood flow increases. Recently, new reference values were proposed for clinical use which included the observed VA at full inflation; this was claimed to "eliminate the need for Kco". In this commentary, some mechanisms e.g. respiratory muscle weakness, lung resection, diffuse alveolar damage and airflow obstruction, which decrease or increase total lung capacity (TLC) are reviewed. Even when alveolar structure and function are normal, the change in Kco at a given VA varies according to the underlying pathophysiological mechanism. The advantages and disadvantages of normalizing Kco and TL,co to predisease predicted TLC or to the patient's actual VA (using lack of expansion or loss of alveolar units models) are considered. Examination of carbon monoxide transfer coefficient and alveolar volume separately provides information on disease pathophysiology which cannot be obtained from their product, the carbon monoxide transfer factor.

Asbestos-related benign pleural disease

Benign pleural disease is the commonest manifestation of asbestos exposure encountered by radiologists. Benign pleural thickening can appear as circumscribed parietal pleural plaques or as more diffuse thickening of the visceral pleura. Benign-asbestos induced pleural effusions are a significant and under-recognized manifestation of asbestos exposure with important sequelae, such as diffuse pleural thickening which may be associated with functional impairment and for which compensation may be sought. This review concentrates on the strengths and weaknesses of chest radiography and computed tomography for the detection and characterization of benign asbestos-related pleural disease and the relevance of imaging abnormalities to compensation and functional impairment.Peacock, C. (2000). Clinical Radiology55, 422-432.

New developments in asbestos-related pleural disease

Images

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.

Respiratory muscle function in patients with asbestos-related pleural disease

The effect of asbestos-related pleural disease (ARPD) on the generation of maximum respiratory pressure was investigated in 11 male patients with ARPD mean age 57 years, range 45-74, and mean duration of asbestos exposure of 9.9 years, range 5-16. There were three smokers, seven ex-smokers and one non-smoker. Breathlessness ranged from grade 1-3 on the MRC score. The extent of pleural disease was calculated using a score based on the ILO score for pleural disease. Full respiratory function tests, global respiratory muscle strength and diaphragmatic strength were assessed. Respiratory muscle strength, including diaphragm strength, was normal. Recoil pressure was high or at the upper limit of normal in four patients and correlated with chest radiograph score for pleural disease (r = 0.65, P < 0.02). There was no difference in either global respiratory muscle or diaphragmatic strength between patients with and without involvement of one or both costophrenic angles or between patients with mild or severe breathlessness. We conclude that respiratory muscle strength is not importantly reduced in ARPD, and it is unlikely that weakness contributes to breathlessness in these patients. By contrast reduced chest wall compliance is likely to be an important factor in breathlessness in some cases.

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.

Asbestos-related pericardial thickening detected by magnetic resonance imaging

Magnetic resonance imaging was performed in four male asbestos workers in whom the chest radiograph revealed pleural but not pulmonary or pericardial disease. Patients underwent thoracic multislice spin echo imaging, with measurement of left and right ventricular volumes at end-diastole and end-systole, and a study of the flow in the superior vena cava as an indirect measure to the filling of the right ventricle. Patients also underwent respiratory function tests and high-resolution computed tomography (HRCT). Magnetic resonance, but not HRCT, showed pericardial thickening in two patients. Magnetic resonance demonstrated reduced diastolic flow in the superior vena cava in one patient, reflecting impaired right ventricular filling. All other magnetic resonance measurements of cardiac function were normal. HRCT demonstrated mild asbestosis in three patients in which neither the chest radiograph nor magnetic resonance showed signs of parenchymal disease, and pericardiac calcification without thickening in one patient. It is concluded that magnetic resonance is superior to HRCT in identifying pericardial thickening, but that HRCT is superior to magnetic resonance in identifying asbestos-related pleural and pulmonary disease.

Pleural thickening: a comparison of oblique chest radiographs and high-resolution computed tomography in subjects exposed to low levels of asbestos pollution

The present study was conducted to investigate the value of oblique chest radiographs, compared with high-resolution computed tomography (HRCT), in the assessment of pleural asbestosis in a group of subjects exposed to low levels of asbestos pollution. The study population consisted of 23 people derived from a previously reported cohort of subjects working in university buildings insulated with asbestos-containing material. Subjects were selected on a voluntary basis from among patients whose initial oblique chest X-rays showed pleural thickening. Sixteen patients were maintenance workers occupationally exposed to asbestos; the remaining seven were environmentally exposed to asbestos. For each subject, two standard chest radiographs [posteroanterior (PA) and right anterior oblique (RAO) views] were taken and HRCT was performed. Films were interpreted after agreement by three chest physicians and a radiologist. Pleural thickening was considered present in all 23 patients on RAO films and in six patients on PA films. HRCT revealed unequivocal pleural plaques in three maintenance workers and doubtful pleural abnormalities in three other maintenance workers. Considering HRCT as the "gold standard," the positive predictive value of RAO film was only 13%-26%. Most of the 17 false-positive diagnoses of pleural fibrosis were due to significant subpleural fat. These results suggest that the routine use of oblique radiographs as a screening test in cohorts of subjects exposed to low levels of pollution by asbestos should be reevaluated.

A new high resolution computed tomography scoring system for pulmonary fibrosis, pleural disease, and emphysema in patients with asbestos related disease

The aim of this study was to describe a scoring system for high resolution computed tomographic (HRCT) scans analogous to the International Labour Office (ILO) scoring system for plain chest radiographs in patients with asbestos related disease. Interstitial fibrosis, pleural disease, and emphysema were scored, the reproducibility and the interobserver agreement using this scoring system were examined, and the extent of the various types of disease was correlated with measurements of lung function. Sixty asbestos workers (five women and 55 men) mean age 59 (range 34-78) were studied. The lungs were divided into upper, middle, and lower thirds. An HRCT score for the extent of pleural disease and pulmonary disease in each third was recorded in a way analogous to the International Labour Office (ILO) method of scoring pleural and parenchymal disease on chest radiographs. A CT score for the extent of emphysema was also recorded. Pleural disease and interstitial fibrosis on the plain chest radiographs were assessed according to the ILO scoring system. A chest radiographic score for emphysema analogous to that used for HRCT was also recorded. Two independent readers assigned HRCT scores that differed by two categories or less in 96%, 92%, and 85% compared with 90%, 78%, and 79% of cases for chest radiographs for fibrosis, emphysema, and pleural disease respectively. There was better intraobserver repeatability for the HRCT scores than for the chest radiograph scores for all disorders. Multiple regression analysis showed that scores for interstitial fibrosis, emphysema, and pleural disease on chest radiographs and HRCT correlated to a similar degree with impairment of lung function.