DLA-Net: dual lesion attention network for classification of pneumoconiosis using chest X-ray images

Accurate and early detection of pneumoconiosis using chest X-rays (CXR) is important for preventing the progression of this incurable disease. It is also a challenging task due to large variations in appearance, size and location of lesions in the lung regions as well as inter-class similarity and intra-class variance. Compared to traditional methods, Convolutional Neural Networks-based methods have shown improved results; however, these methods are still not applicable in clinical practice due to limited performance. In some cases, limited computing resources make it impractical to develop a model using whole CXR images. To address this problem, the lung fields are divided into six zones, each zone is classified separately and the zone classification results are then aggregated into an image classification score, based on state-of-the-art. In this study, we propose a dual lesion attention network (DLA-Net) for the classification of pneumoconiosis that can extract features from affected regions in a lung. This network consists of two main components: feature extraction and feature refinement. Feature extraction uses the pre-trained Xception model as the backbone to extract semantic information. To emphasise the lesion regions and improve the feature representation capability, the feature refinement component uses a DLA module that consists of two sub modules: channel attention (CA) and spatial attention (SA). The CA module focuses on the most important channels in the feature maps extracted by the backbone model, and the SA module highlights the spatial details of the affected regions. Thus, both attention modules combine to extract discriminative and rich contextual features to improve classification performance on pneumoconiosis. Experimental results show that the proposed DLA-Net outperforms state-of-the-art methods for pneumoconiosis classification.

[Guidelines for the use of the International Classification of Radiographs of Pneumoconioses of the International Labour Office (ILO): Substantial changes in the currrent edition]

The International Classification of Radiographs of Pneumoconioses is the scheme worked out by the International Labour Office in Geneva (ILO), to register radiographic chest abnormalities in a well-ordered, reproducible and comparable way. It is used for diagnosing abnormalities caused by dust exposure. Guidelines for the use of the ILO International Classification of Radiographs of Pneumoconioses contain detailed information and recommendations on how to use the classification, as well as how the chest X-ray examination should be performed and recorded. To facilitate the diagnosis of observed abnormalities the classification is completed by the set of standard radiograms illustrating typical irregularities referring to lungs and pleura, included in the classification. The article presents the key information on classification and the most important amendments adopted in the 2000 and 2011 ILO guidelines revisions. These changes refer to radiographs quality assessment, the way of presenting abnormalities registered in standard radiographs (QUAD set, digital images) and registration of failures not related to dust exposure. Particularly important complements result from the development of radiological imaging techniques. They are concerned about the classification of radiographic images of the chest recorded digitally. Med Pr 2016;67(6):833-837.

Relationships (II) of International Classification of High-resolution Computed Tomography for Occupational and Environmental Respiratory Diseases with ventilatory functions indices for parenchymal abnormalities

The International Classification of High-Resolution Computed Tomography (HRCT) for Occupational and Environmental Respiratory Diseases (ICOERD) is used to screen and diagnose respiratory illnesses. Using univariate and multivariate analysis, we investigated the relationship between subject characteristics and parenchymal abnormalities according to ICOERD, and the results of ventilatory function tests (VFT). Thirty-five patients with and 27 controls without mineral-dust exposure underwent VFT and HRCT. We recorded all subjects' occupational history for mineral dust exposure and smoking history. Experts independently assessed HRCT using the ICOERD parenchymal abnormalities (Items) grades for well-defined rounded opacities (RO), linear and/or irregular opacities (IR), and emphysema (EM). High-resolution computed tomography showed that 11 patients had RO; 15 patients, IR; and 19 patients, EM. According to the multiple regression model, age and height had significant associations with many indices ventilatory functions such as vital capacity, forced vital capacity, and forced expiratory volume in 1 s (FEV1). The EM summed grades on the upper, middle, and lower zones of the right and left lungs also had significant associations with FEV1 and the maximum mid-expiratory flow rate. The results suggest the ICOERD notation is adequate based on the good and significant multiple regression modeling of ventilatory function with the EM summed grades.

Relationships (I) of International Classification of High-resolution Computed Tomography for Occupational and Environmental Respiratory Diseases with the ILO International Classification of Radiographs of Pneumoconioses for parenchymal abnormalities

The International Classification of High-resolution Computed Tomography (HRCT) for Occupational and Environmental Respiratory Diseases (ICOERD) has been developed for the screening, diagnosis, and epidemiological reporting of respiratory diseases caused by occupational hazards. This study aimed to establish a correlation between readings of HRCT (according to the ICOERD) and those of chest radiography (CXR) pneumoconiotic parenchymal opacities (according to the International Labor Organization Classification/International Classification of Radiographs of Pneumoconioses [ILO/ICRP]). Forty-six patients with and 28 controls without mineral dust exposure underwent posterior-anterior CXR and HRCT. We recorded all subjects' exposure and smoking history. Experts independently read CXRs (using ILO/ICRP). Experts independently assessed HRCT using the ICOERD parenchymal abnormalities grades for well-defined rounded opacities (RO), linear and/or irregular opacities (IR), and emphysema (EM). The correlation between the ICOERD summed grades and ILO/ICRP profusions was evaluated using Spearman's rank-order correlation. Twenty-three patients had small opacities on CXR. HRCT showed that 21 patients had RO; 20 patients, IR opacities; and 23 patients, EM. The correlation between ILO/ICRP profusions and the ICOERD grades was 0.844 for rounded opacities (p<0.01). ICOERD readings from HRCT scans correlated well with previously validated ILO/ICRP criteria. The ICOERD adequately detects pneumoconiotic micronodules and can be used for the interpretation of pneumoconiosis.

[The problems of classification of the occupational interstitial lung diseases, approaches to solving]

The analysis of the applied in Russia classifications of pneumoconiosis and occupational hypersensitivity pneumonitis in relation to the international classifications of occupational lung diseases and the classification of interstitial lung diseases (ILD) was performed. The necessity of a new approach to the classification of occupational ILD was proved and solutions of the problem were offered.

Utility of digital radiography for the screening of pneumoconiosis as compared to analog radiography: radiation dose, image quality, and pneumoconiosis classification

The purpose of this study was to compare digital radiography (DR) and analog radiography (AR) for the screening of pneumoconiosis with respect to radiation dose, image quality, and pneumoconiosis classification. DR was performed on 50 subjects who were enrolled for an examination of pneumoconiosis (Digital Diagnost™, Philips, Netherlands), and AR (MXO-15B, Toshiba, Japan) was performed the same day after the study was approved by the Institutional Review Board and written informed consent was obtained from all subjects. Entrance surface doses (ESDs) of DR and AR were measured using a glass dosimeter attached to a Rando human phantom (Alderson Co., U.S.) under exposure conditions commonly used in clinical practice in Korea. Visibilities on all images were evaluated using a 5-point scale by four chest radiologists using a modified form of the European Chest Guidelines (EUR 16260). All the images were classified using the ILO's guidelines by referencing standard analog radiographs. ESDs of DR were significantly lower than those of AR (0.15 mGy vs. 0.21 mGy, p < 0.05). All anatomic structures were significantly more visible by DR images (p < 0.0001), especially the left main bronchus, ribs, and thoracic spine. Body mass index did not correlate with anatomic structure visibility by DR (r = -0.029, p = 0.842) or AR images (r = -0.076, p = 0.602). Overall intra- and inter-reader agreements for DR images were significantly higher than for AR images. DR offers improved image quality with a significant reduction of up to 23.6% in radiation dose and more accurate pneumoconiosis classification than AR.

Proficiency in reading pneumoconiosis radiographs examined by the 60-film set with 4-factor structuring 8-index

29 physicians (A1-Group) and 24 physicians (A2-Group) attending the 1st and 2nd "Asian Intensive Reader of Pneumoconiosis" (AIR Pneumo) training course, respectively, and 22 physicians (B-Group) attending the Brazilian training course took the examination of reading the 60-film set. The objective of the study was firstly to investigate the factor structure of physicians' proficiency of reading pneumoconiosis chest X-ray, and secondly to examine differences in factor scores between groups. Reading results in terms of the 8-index of all examinees (Examinee Group) were subjected to the exploratory factor analysis. A 4-factor was analyzed to structure the 8-index: the specificity for pneumoconiosis, specificity for large opacities, specificity for pleural plaque and shape differentiation for small opacities loaded on the Factor 1; the sensitivity for pneumoconiosis and sensitivity for large opacities loaded on the Factor 2; the sensitivity for pleural plaque loaded on the Factor 3; the profusion increment consistency loaded on the Factor 4. 4-Factor scores were compared between each other of the three groups. The Factor 2 scores in A1 and A2 groups were significantly higher than in B-Group. Four factors could reflect four aspects of reading proficiency of pneumoconiosis X-ray, and it was suggested that 4-factor scores could also assess the attained skills appropriately.

[Lung ventilation parameters in various pneumoconiosis forms during follow-up in miners of Kouzbass]

Studies of spirometric parameters in 120 miners who live in Kemerovo region and suffer from diagnosed pneumoconiosis demonstrated disordered pulmonary ventilation in 53.3% of the examinees. The highest velocity parameters in spirometry are seen in nodular form, the lowest ones--in mixed form of pneumoconiosis. During 2 years of follow-up forced expiratory volume over the first second decreased. Velocity and volume spirometric parameters in pneumoconiosis among coal miners of Kemerovo region under 2 years of follow-up demonstrate invert correlation with initial age of the patients when pneumoconiosis was diagnosed.

[On parity in development of obstructive and restrictive changes in miners]

Spirometric studies in 397 miners having pneumoconiosis and chronic dust bronchitis demonstrated 80% occurrence of respiratory failure with equally marked obstructive and restrictive disorders. Therefore, bronchopulmonary diseases in miners do not match the criteria of chronic obstrictive lung disease.

Association of cytokine gene polymorphisms in CWP and its severity in Turkish coal workers

BACKGROUND

Cytokines appear to play a key role in some inflammatory reactions affecting the interactions among pro- and anti-inflammatory mechanisms that result in several diseases such as coal workers' pneumoconiosis (CWP). In this study, to determine the cytokine gene profiles of Turkish coal miners, we performed genotyping analysis to investigate the polymorphisms of CWP-related pro-inflammatory (TNFA, IL1A, IL1B, and IL6) and anti-inflammatory cytokines (IL-1RN and TGFB1). An additional goal was to observe whether these cytokine gene polymorphisms influence the development risk and severity of.

METHODS

Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

RESULTS

TNFA (-238) gene polymorphism principally affected CWP development and severity (OR = 3.47: 95% CI, 1.12-10.77 and OR = 4.30: 95% CI, 1.25-14.74, respectively) and also risk of CWP (OR = 3.79: 95% CI, 1.37-10.46). The TNFA (-308) variant was associated with a risk for the CWP severity (OR = 2.84: 95% CI, 1.08-7.39). A protective effect of IL6 was found on the development (OR = 0.48: 95% CI, 0.21-0.93) and severity of CWP (OR = 0.37: 95% CI, 0.15-0.91).

CONCLUSIONS

We suggest that TNFA (-238) variant may be a risk factor in both development and the severity of CWP, while TNFA (-308) variant seems to be important only in disease severity. On the other hand, IL6 variant may have a protective effect on the development and disease severity.

Outras pneumoconioses

As pneumoconioses mais prevalentes são a silicose, a asbestose e a pneumoconiose do trabalhador do carvão. Outras pneumoconioses com repercussões clínicas, funcionais e estruturais distintas são causadas pela inalação de poeiras metálicas a partir de fumos metálicos e sais orgânicos. A distinção quanto à forma química do composto inalado tem relação com a reação tecidual e o prognóstico. São apresentadas de forma sucinta a pneumoconiose simples, a siderose, a pneumoconiose por rocha fosfática, e a doença pulmonar crônica pelo berílio e por exposição a metais duros. Uma anamnese ocupacional como instrumento de busca etiológica dessas pneumoconioses é essencial.

Selection of reference films based on reliability assessment of a classification of high-resolution computed tomography for pneumoconioses

OBJECTIVE

Worldwide demand has increased for the development of a computed tomography (CT) classification system that supplements the ILO classification of radiographs for pneumoconioses. The authors aimed to show preliminary reliability test results for selected referent films for the CT classification system developed through an international effort by researchers from seven countries.

METHODS

Reading trials by eight physicians who have considerable experience in pneumoconioses using a total of 114 lung zones consisting of 6 lung zones of 19 CT films of dust-exposed workers were performed to assess reliability of the classification system by weighted kappa. The results were also utilized for selecting reference films.

RESULTS

A good agreement was observed for both first and second reading trials for rounded opacities (weighted kappa=0.76, 0.74, first and second trial results, respectively), irregular opacities (0.60, 0.48), emphysema (0.56, 0.70) and honeycombing (0.72, 0.79). Ground glass opacities, on the other hand, showed moderate agreement (0.43, 0.38). Intra-reader agreements among eight readers were shown in the same table as the mean and standard deviation of weighted kappa statistics. The inter-reader agreement for pleural thickening was not as good as for parenchymal lesions.

DISCUSSION

The CT classification development may pioneer noble and sensitive medical screening for dust-exposed workers in selected settings. This system may be applied to radiographic borderline cases of profusion 0/1 and 1/0 by the ILO classification, in a setting that assures the occupational safety and health of workers exposed to some newly developed chemical compounds.

Proposed criteria for mixed-dust pneumoconiosis: Definition, descriptions, and guidelines for pathologic diagnosis and clinical correlation1 1The NIKKO-Symposium on Mixed-Dust Pneumoconiosis was held October 18–19, 1997, in Nikko, Tochigi, Japan, to develop diagnostic criteria for mixed-dust pneumoconiosis under the auspices of Labour Welfare Corporation, Tokyo, Japan. The Organizing Committee included Keizo Chiyotani, Koichi Honma, Yutaka Hosoda, and Hisao Shida, and participants included Zoltán Adamis, Eduardo Algranti, Toshiharu Fuyuki, Kiyonobu Kimura, Otha Linton, Michihito Mishina, Hiroshi Morikubo, Alvaro R. Osornio-Vargas, Yoshiaki Saitoh, Yasushi Shinohara, and Hiroshi Watanabe

We defined mixed-dust pneumoconiosis (MDP) pathologically as a pneumoconiosis showing dust macules or mixed-dust fibrotic nodules (MDF), with or without silicotic nodules (SN), in an individual with a history of exposure to mixed dust. We defined the latter arbitrarily as a mixture of crystalline silica and nonfibrous silicates. According to our definition of MDP, therefore, MDF should outnumber SN in the lung to make a pathologic diagnosis of MDP. In the absence of confirmation of exposure, mineralogic analyses can be used to support the pathologic diagnosis. The clinical diagnosis of MDP requires the exclusion of other well-defined pneumoconioses, including asbestosis, coal workers' pneumoconiosis, silicosis, hematite miners' pneumoconiosis, welders' pneumoconiosis, berylliosis, hard metal disease, silicate pneumoconiosis, diatomaceous earth pneumoconiosis, carborundum pneumoconiosis, and corundum pneumoconiosis. Typical occupations associated with the diagnosis of MDP include metal miners, quarry workers, foundry workers, pottery and ceramics workers, and stonemasons. Irregular opacities are the major radiographic findings in MDP (ILO 1980), in contrast to silicosis, in which small rounded opacities predominate. Clinical symptoms of MDP are nonspecific. MDP must be distinguished from a variety of nonoccupational interstitial pulmonary disorders.

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.

[Further development of the International Pneumoconiosis Classification--from ILO 1980 to ILO 2000 and to ILO 2000/German Federal Republic version]

The ILO (1980) Classification has been revised during recent years. The new version is now available as the International Classification of Radiographs of Pneumoconioses (Revised edition 2000). The Guidelines booklet is currently available only in English. Those involved felt it was important to maintain continuity with the ILO (1980) edition, in particular to retain the standard radiographs, despite their restricted quality, so as to ensure comparability with earlier national and international data sets. The standard films illustrating pleural abnormalities, and 'u'-shadows, have been modified and reconstituted. The most important changes relate to assessment of film quality, pleural abnormalities, and additional symbols. In Germany, film quality is characterised as "+", "+-", "+--" and "u" according to whether the ability to assess pneumoconiosis is judged to be unimpeachable ("+") to unusable ("u"). If a film is not classified as "+", then written comments regarding defects are required. For "diffuse" pleural thickening, the ILO (2000) edition now requires the presence also of obliteration of the costophrenic angle. This was not required in the earlier (1980) edition and, as previously, is also not stipulated in the German version. A minimum width of 3 mm (previously 0-5 mm), coded "a", is required both for plaques as well as for the margin to the lateral chest wall. Congruence is thus achieved for criteria, which, in German practice, lead to an indication of suspect occupational disease. Plaques on the diaphragm are not considered for measurement of extent; they are only coded as present or absent. If calcification is identified, then this must also be classified and measured as a localised plaque. Extent of calcification on its own, previously coded "0" to "3", is no longer specified. The following new symbols, illustrated by new diagrams, have been introduced: aa = atherosclerotic aorta; at = apical thickening; cg = calcified granuloma (or other non-pneumocononiotic nodules); me = mesothelioma (already previously differentiated from "ca" on the German record sheet); pa = plate atelectasis; pb= parenchymal bands; ra = rounded atelectasis; od = other disease. (Examples of the latter are illustrated diagrammatically by lobar pneumonia, aspergilloma, goiter and hiatal hernia.) Earlier national differences (ILO 1980/German Federal Republic) on particular issues have also been agreed among German "double-readers" ["Zweitbeurteiler"]. However, conformity between the original (ILO 2000) text and the national (German) modified text has been retained in large measure. The detailed descriptions of the standard films differ in certain respects from the German (1980) definitions. Some revision of individual descriptions of the films are proposed. Except for a few differences, agreement was reached here too. The definitive date for the change in Germany is expected to be in early 2004. The standard films are already available now through ILO offices in Geneva or Bonn (addresses in appendix.)

[Pathogenesis and classification of dust-related disease]

The author justifies basic principles for new dust diseases classification resting upon contemporary ideas concerning pathogenesis of occupational respiratory diseases caused by dust.

Occupational Lung Disease in China

Occupational lung disease has been a major public health problem in China. The recently transformed industrial structure and expansion of the industrial labor force, accompanying the rapid industrialization and economic growth, pose both tremendous challenges and opportunities for occupational health policy and research. New occupational health problems are emerging, while the traditional occupational lung disease continued to occur. Simultaneously, relevant scientific research and professional activities have accelerated notably. The progress and achievement in occupational health research are creating more powerful forces in eliminating industrial hazards and protecting workers' health in China.

International Labor Office Classification System in the age of imaging: relevant or redundant

The 1980 International Labor Office International Classification of Radiographs of Pneumoconioses is a widely used epidemiologic tool with a storied past. This article reviews its development and examines its applications to occupational lung disease and the controversies generated in that process. The question of its relevancy to current imaging practices is discussed.

[Comparison of digital selenium radiography with an analog screen-film system in the diagnostic process of pneumoconiosis according to ILO classification]

Comparison of digital selenium radiography with an analog screen-film system in the diagnostic process of pneumoconiosis according to ILO classification.

PURPOSE

The aim of the study was to determine the diagnostic value of digital selenium radiography in patients with pneumoconiosis. For this purpose chest x-rays by digital selenium radiography and analog screen-film system were compared according to the ILO classification of pneumoconiosis.

METHOD

After approval of the study by the local ethic commission and the Federal German Office for Radiation Protection 50 patients were subjected to x-rays by digital selenium radiography (Thoravision; Philips Medical Systems, Hamburg, Germany) and analog screen-film system of the same day within the scope of an industrial medicine preventive checkup. Four investigators rated the chest x-rays according to the ILO classification of pneumoconiosis.

RESULTS

The findings demonstrated by chest x-rays according to ILO classification were rated similar by digital selenium radiography and analog screen film systems. Image quality of the digital pictures was rated significantly better.

CONCLUSION

The use of digital selenium radiography in evaluating chest x-rays according to the ILO classification does not result in over- or underestimation of pulmonary pathologies. Hence, in the diagnosis of pneumoconiosis, digital selenium radiography can replace the tested analog screen-film system.

[Classification of pneumoconiosis]

The article presents a modern classification of pneumoconiosis taking account of the international classification and experience gained by specialists in this country.

łGradation of sideropneumoconiosis

Pathological-anatomical analyses of biopsy and autopsy samples of 43 men with anamnestically established occupational exposure to welding fumes showed in 38 specimens (88%) characteristic alterations of varying degrees of sidero pneumokonioses. Based on recurrent histological findings of increase and activation of iron storing macrophages (siderophages) and varying degrees of fibrosis, sidero pneumokonioses are classified into three grades. Intraindividually and also toporegionally different degrees may well be present. Based on morphological criteria of the three grades, seven samples were classified as grade I, 21 specimens as grade II, and 10 samples as grade III. The results show that exposure to welding fumes may well cause pulmonary alterations reaching an impairment level, depending on length, extent and special circumstances of the respective exposure. In cases of so-called welders lungs, an obliging statement in an expert's opinion on the degree of functional impairment, however, can only be given when histological findings, detailed information on the occupational history and clinical functional parameters are combined.

Pathology and pathophysiology of pneumoconiosis

Cellular and molecular mechanisms, as well as associated gene expressions, in silicosis and asbestosis are widely investigated, and compound mechanisms involved in initiating inflammation and progression to fibrosis are comprehensively studied, though not yet totally understood. Recent advances in this field, especially concerning pathophysiology of these pneumoconioses, are reviewed in this article. Silicosis and asbestosis are two major types of pneumoconiosis. Although the clinico-pathologic features presented are apparently different, silicosis and asbestosis are both interstitial lung diseases caused by chronic exposure to airborne inorganic dusts, and the pathology of these two diseases is essentially a fibrosis.

Variability in the classification of radiographs using the 1980 International Labor Organization Classification for Pneumoconioses

This study describes the extent of agreement in classification of chest radiographs using the International Labor Organization (ILO) classification among six readers from the United States and Canada. A set of 119 radiographs was created and read by three Canadian and three US readers. The two ratings of interest were profusion (scored from 0/- to 3/+) and pleural abnormalities consistent with pneumoconiosis (scored with the ILO system, then collapsed into a yes/no). We used a number of approaches to evaluate interreader agreement on profusion and pleural changes, determining concordance, observed agreement, kappa statistic, and a new measure to approximate sensitivity and specificity. This study found that five of six readers had good fair to good agreement for pleural findings and for profusion as a dichotomous variable (> or = 1/0 vs < or = 0/1) using the kappa statistic, while a sixth reader had poor agreement. We found that concordance, expressed as percent agreement, was higher for normal radiographs than for ones that showed disease, and describe the use of the kappa statistic to control for this finding. This analysis adds to the existing literature with the use of the kappa statistic, and by presenting a new measure for "underreading" and "overreading" tendencies.

[Yesterday's and today's pneumoconiosis]

Pneumoconioses are still a frequent cause of interstitial lung disease, that can be lethal. Nevertheless, the improvement of working conditions has led to a lower incidence of severe forms of disease. More sensitive diagnostic techniques, such as high resolution computed tomography scan, are used in early diagnosis and in the medico-legal expertise. Immunological techniques and mineralogical analyses of biological samples allow a more rigorous work-up in these cases. In this regard, bronchoalveolar lavage can bring very interesting information from the cellular, immunological, and mineralogical points of view.

Evaluation and classification of high-resolution computed tomographic findings in patients with pneumoconiosis

The standard ILO classification for pneumoconiotic changes using conventional X-ray films has become well established. In recent years computed tomography has played an increasing role in occupational medicine and above all in the assessment of pneumoconiosis. Therefore a standardised method of classification for CT also seems necessary. A system of classification developed by occupational hygienists and radiologists allows a detailed description of parenchymal and pleural changes and the use of 28 additional symbols. Furthermore, special diagnoses relevant to occupational medicine and additional comments can be made. The classification system was tested in practice in the research project "Early diagnosis of asbestos-related diseases" (Frühdiagnostik asbestverursachter Erkrankungen). It was shown to be both practicable and easily reproducible, intra-individually and interindividually.

[Clinical study of pneumoconiosis featuring small nodules and without large opacities on high-resolution CT]

High-resolution CT (HRCT) was performed in 25 patients with pneumoconiosis diagnosed as category 1 or 2 according to the ILO radiographic classification. The small opacities shown on HRCT images were classified as small branching structures (SBS) or small rounded opacities (SRO). Patients in these two groups were compared with respect to the distribution of small nodules, pulmonary function, arterial blood gas analysis, degree of exertional dyspnea, and alteration ratio of the lung field CT numbers between maximum inspiration and maximum expiration (%(I-E)). The small nodules in all patients of the SBS group were classified as type p. SBS were distributed evenly throughout the lungs, while SRO were mainly localized in the upper middle lobe. Pulmonary emphysema was observed in patients with SBS and was particularly common among patients in this group with an irregular septum (IS). No emphysematous lesions were detected in the SRO group. RV/ TLC was higher and exertional dyspnea was more severe in the SBS group than in the SRO group. It was considered that an increase of RV/TLC resulted in worsening of exertional dyspnea in the patients with SBS. The % (I-E) value was significantly lower in the SBS group than in the SRO group.

[The classification of pneumoconioses]

The article deals with analysis of scientific data concerning etiology, pathogenesis, clinical and roentgenologic manifestations, morphologic appearances and other aspects to precise and refine the former idea of pneumoconioses. The authors present the main principles for improved classification of pneumoconioses.

Chest radiography in dust-exposed miners: promise and problems, potential and imperfections

Since the early 1900s, it was recognized that many dust-exposed workers developed abnormal radiographs during life. Chest radiography remains the primary means of determining the presence and extent of dust-induced pneumoconiosis, although it is ineffective for detecting airways obstructions from mine dust exposure. This chapter reviews the uses and limitations of chest radiography in the study, surveillance, screening, clinical diagnosis, and disability determinations of occupational lung diseases in dust-exposed workers.

The 1980 ILO classification of radiographs of the pneumoconioses

The 1980 ILO classification of radiographs of the pneumoconioses has undergone revision and improvement in response to increases in knowledge and international concerns. Its goal is to standardize the reading and reporting of radiographic manifestations of the inhalation of dust so that international epidemiologic comparisons are possible. It remains an imperfect instrument, but "... although total elimination of variation is impossible, some measure of control can be achieved."

The international labour office classification: use and misuse

The main characteristics of the International Labour Office (ILO) International Classification of Radiographs of the Pneumoconioses (1980) are reviewed. Applications to epidemiological, research, and clinical problems are outlined. The need for multiple readings, reading protocols and appropriate administrative arrangements is emphasized. Possible improvements to the Classification are discussed. The basic descriptive features of the scheme are distinguished from supplementary interpretative facilities; it is suggested that misuse of the Classification occurs primarily when these two functions are confused.

A comparison of pneumoconiosis interpretation between Chinese and American readers and classifications

As a preliminary step in joint Sino-American pneumoconiosis research efforts, a formal chest X-ray pneumoconiosis reading trial was conducted among Chinese and American radiologists. Twelve Chinese readers from different institutions located in south central China used the 1986 Chinese Roentgenodiagnostic Criteria of Pneumoconioses. Three American radiologists, centified as NIOSH "B" readers, used the International Labour Office Classification of Pneumoconioses. The chest X-ray study set consisted of 150 posterior-anterior films. One-half were Chinese X-rays of silica-exposed workers, and the other half were American films of variously exposed workers but primarily coal miners. All readings were done independently. The results showed that the inter-reader variability among the Chinese was similar to that of the American readers, both being in an acceptable range. In addition, there was general agreement between the Chinese and American interpretations. For small opacity profusion, the Chinese readers tended to read slightly more diseases than their American counterparts, although there was exact agreement as to the major category in two-thirds of the films. Agreement for film quality, and pleural disease was less, but was not different from reported variation among American "B" readers. Overall, the results suggest that despite the use of two different classification systems, a valid correspondence exists between the Chinese and American Interpretations, which is suitable for use in epidemiologic research.

Pulmonary function and pleural fibrosis: quantitative relationships with an integrative index of pleural abnormalities

Pleural fibrosis due to asbestos exposure was fully appreciated considerably later than pulmonary interstitial fibrosis due to similar exposure. This is well exemplified by the fact that pleura face on was included in the International Labour Office's International Classification of Radiographs of Pneumoconioses only in the last revision of the Classification. The functional relevance of pleural fibrosis, in particular circumscribed pleural fibrosis, has remained controversial. Since pleural fibrosis can occur at various sites (diaphragmatic plaques, chest wall in profile and face on, mediastinal) and can be of different thickness and extent, a comprehensive integrative assessment of pleural fibrosis was undertaken in order to permit a quantitative study of relationships between pleural fibrosis and pulmonary function. This approach was used for chest X-ray films of 1,584 asbestos insulation workers examined (1981-1983); 1,185 (75%) had pleural fibrosis. The distribution pattern of the integrative pleural index was found to be different in the subgroup with circumscribed (n = 975) from that with diffuse (n = 197) pleural fibrosis, with a higher profusion of high INDEX values in the latter. Stepwise regression analysis indicated that there was a significant inverse relationship between forced vital capacity (FVC) and the integrative index of pleural fibrosis in the subgroup with circumscribed pleural fibrosis. In the subgroup with diffuse pleural fibrosis, the obliteration of costophrenic angle(s), even with pleural fibrosis of limited extent, resulted in marked decrement in FVC% predicted; higher values of INDEX did not result in additional significant reductions of FVC. In those with both parenchymal and pleural abnormalities (n = 862) the pleural index was found to make a significant contribution, independent of that of parenchymal abnormalities, to decrements of FVC. Since pleural fibrosis has gradually become the predominant radiologically detectable abnormality in asbestos exposed workers, establishing its quantifiable functional relevance is useful.

Pneumoconiosis: an occupational hazard

The use of radiography to detect pneumoconiosis is a familiar task to radiographers in coal mining states. This article includes a discussion on pneumoconiosis and coal workers' pneumoconiosis (black lung) as well as the radiographic findings associated with pneumoconiosis and the federal act that established the black lung program in the United States.