Silicosis in 76 men: qualitative and quantitative CT evaluation--clinical-radiologic correlation study

Imaging diagnosis of pneumoconiosis with predominant nodular pattern: HRCT and pathologic findings

The radiological patterns of known pneumoconiosis have been changing in recent years. The basic pathology in pneumoconiosis is the presence of dust macules, mixed dust fibrosis, nodules, diffuse interstitial fibrosis, and progressive massive fibrosis. These pathologic changes can coexist in dust-exposed workers. High resolution CT reflects pathological findings in pneumoconiosis and is useful for the diagnosis. Pneumoconiosis such as silicosis, coal workers' pneumoconiosis, graphite pneumoconiosis, and welder's pneumoconiosis, has predominant nodular HRCT pattern. Diffuse interstitial pulmonary fibrosis is sometimes found in the lungs of this pneumoconiosis. In the early stages of metal lung, such as aluminosis and hard metal lung, centrilobular nodules are predominant findings, and in the advanced stages, reticular opacities are predominant findings. The clinician must understand the spectrum of expected imaging patterns related to known dust exposures and novel exposures. In this article, HRCT and pathologic findings of pneumoconiosis with predominant nodular opacities are shown.

Volume-based tomography for the diagnosis of incipient silicosis in former gold miners

Objective

To evaluate silicosis diagnosed through CT, with integration of clinical-occupational data, in silica-exposed workers presenting chest X-rays within International Labor Organization (ILO) category 0.

Methods

Cross-sectional study with 339 former gold miners, with comparable exposures and X-rays classified as ILO subcategory 0/0 (n=285) and 0/1 (n=54) were submitted to volume-based CT. The findings were classified according to the International Classification of HRCT CT for Occupational and Environmental Respiratory Diseases.

Results

A profusion degree of round opacities (RO)>1 was found in 22.4% (76/339) of the CT exams. After integrating the CT findings with clinical and occupational data, silicosis was diagnosed as follows: 43/285 (15.1%) and 14/54 (25.9%) in workers whose X-rays had been classified as 0/0 and 0/1, respectively. There was an upward trend towards longer exposures, reaching 38.9% when working more than 10 years underground and classified as 0/1 (p=0019). Those with presence of RO whose final diagnosis was not silicosis were mainly cases of tuberculosis or ‘indeterminate nodules’. Emphysema was found in 65/339 (19.1%), only 5 being detected in the X-ray.

Conclusion

Volume-based CT proved to be useful in the investigation of silicosis among individuals with a relevant exposure to silica, capturing diagnoses that had not been identified on X-rays. A response gradient of silicosis was showed by CT even in this population with ILO category 0 radiographs. It can be indicated based on quantitative and/or qualitative criteria of occupational exposure, especially considering the possibilities of low CT dosage.

Krill oil and low-dose aspirin combination mitigates experimentally induced silicosis in rats: role of NF-κB/TGF-β1/MMP-9 pathway

This study is an attempt to assess pulmonary protective and antifibrotic potentials of a combination of aspirin, a widely used anti-inflammatory and cardioprotective agent, and krill oil, a naturally occurring omega-3 fatty acid source, against silica-induced pulmonary injury. For silicosis induction, silica particles (50 mg/rat, 0.1 mL 0.9% NaCl) were instilled intranasally into rats. Aspirin (10 mg/kg/day), krill oil (40 mg/kg/day), or their combination was administered orally for 56 days following silica exposure. Results showed that oral aspirin and krill oil combination significantly mitigated silica-induced pulmonary injury. Bronchoalveolar lavage fluid examination showed a decreased lactate dehydrogenase activity, total protein content, and accumulation of total and differential inflammatory cells. Oral aspirin and krill oil combination significantly attenuated silica-induced oxidative stress through the restoration of reduced glutathione concentration and catalase activity in addition to alleviation of elevated malondialdehyde and total nitric oxide contents. Moreover, aspirin and krill oil combination revealed considerable mitigation of silica-induced upregulated expression of the inflammatory and fibrotic mediators: nuclear factor kappa-B, transforming growth factor-β1, and matrix metalloproteinase-9. The antifibrotic effect was also evidenced through the decreased hydroxyproline content and the obvious restoration of lung architecture, as demonstrated upon histopathological examination. In conclusion, oral aspirin and krill oil combination can confer pulmonary protective, anti-inflammatory, and antifibrotic potentials against silica-induced pulmonary injury. This impact could be credited to the ability of this combination to activate resolution mechanisms, which, in turn, suppress the expression of inflammatory and fibrotic biomarkers and replenish antioxidant stores.

Evaluation of lung densitometric and volumetric changes in silicosis patients using three-dimensional software for multidetector CT and the relationship with profusion scores

AIM

To evaluate the density and volume changes in the lungs of silicosis patients and their relationship with the disease severity classification of the International Labor Organization (ILO).

MATERIALS AND METHODS

The multidetector computed tomography (CT) images of 44 patients diagnosed with silicosis and 32 controls that underwent thoracic CT due to trauma were evaluated. Patients with silicosis were divided into three categories according to the ILO classification. Data related to the total lung volume, total lung mean density, lung opacity score, percentage of lung high opacity, and mean density in the lower and upper lobes were obtained using three-dimensional (3D) software.

RESULTS

There was no significant difference between the total lung mean densities of the silicosis and control groups (p=0.213); however, a significant difference was observed between the two groups in terms of the total lung volume (p<0.0001). According to the ILO classification, there was a significant difference between the disease severity categories in relation to the percentage of lung high opacity (p=0.000005). A strong correlation was detected between disease severity and high opacity percentage (p<0.0001, r=0.804). According to the ILO classification, there was also a significant difference between disease severity categories in terms of the lung opacity score (p=0.000144), as well as a moderate correlation between disease severity and opacity score (p<0.0001, r=0.580).

CONCLUSION

Total lung volume is a CT finding that shows variation in exposure to crystalline silica. The percentage of high opacity determined using multidetector CT is an effective parameter in evaluating disease severity.

Artificial stone-associated silicosis in China: A prospective comparison with natural stone-associated silicosis

BACKGROUND AND OBJECTIVE

We recently noted a dramatic increase in the number of patients with accelerated silicosis associated with exposure to artificial stone dust. Therefore, the natural history of artificial stone-associated silicosis was compared with that of natural stone-associated silicosis.

METHODS

A total of 18 patients with artificial stone-associated silicosis and 63 with natural stone-associated silicosis were diagnosed sequentially in 2018 and followed up for a period of 6-12 months. Data were collected from clinical charts.

RESULTS

The median duration of exposure prior to onset of symptoms of silicosis was shorter for patients who had been exposed to artificial stone dust (6.4 vs 29.3 years, P < 0.01). Four of the 18 patients experienced rapid deterioration in lung function over the follow-up period, with declines in pre-bronchodilator FVC of 587 (210-960) mL/year and FEV1 of 625 (360-860) mL/year. GGO, PMF, emphysema and pulmonary artery widening were more frequently observed on computed tomography scans of patients with artificial stone-associated silicosis than of those with natural stone-associated silicosis. Approximately 38.9% of the patients with artificial stone-associated silicosis were lung transplant candidates and 27.8% died, both rates being significantly higher than in patients with natural stone-associated silicosis (3.2% and 0%, both P < 0.01).

CONCLUSION

Compared to natural stone-associated silicosis, artificial stone-associated silicosis was characterized by short latency, rapid radiological progression, accelerated decline in lung function and high mortality.

Functional, inflammatory and interstitial impairment due to artificial stone dust ultrafine particles exposure

OBJECTIVE

Artificial stone dust (ASD) contains high levels of ultrafine particles (UFP <1 µm) which penetrate deeply into the lungs. This study aimed to demonstrate the direct effect of UFP in the lungs of ASD-exposed workers on functional inflammatory and imaging parameters.

METHODS

68 workers with up to 20 years of ASD exposure at the workplace were recruited from small enterprises throughout the country and compared with 48 non-exposed individuals. Pulmonary function test (PFT), CT, induced sputum (IS) and cytokine analyses were performed by conventional methods. The CT scans were evaluated for features indicative of silicosis in three zones of each lung. UFP were quantitated by the NanoSight LM20 system (NanoSight, Salisbury) using the Nanoparticle Tracking Analysis. Interleukin (IL)-6, IL-8 and tumour necrosis factor alpha (TNF-α) levels were measured by Luminex (R&D Systems).

RESULTS

Thirty-four patients had CT scores between 0 and 42, and 29 of them were diagnosed with silicosis. Content of the UFP retrieved from IS supernatants correlated negatively with the PFT results (total lung capacity r=-0.347, p=0.011; forced expiratory volume in 1 s r=-0.299, p=0.046; diffusion lung carbon monoxide in a single breath r=-0.425, p=0.004) and with the CT score (r=0.378, p=0.023), and with the inflammatory cytokines IL-8 (r=0.336, p=0.024), IL-6 (r=0.294, p=0.065) and TNF-α (r=0.409, p=0.007). Raw material of ASD was left to sedimentate in water for <15 min, and 50% of the floating particles were UFP. A cut-off of 8×106 UFP/mL in IS samples had a sensitivity of 77% to predict pulmonary disease.

CONCLUSIONS

This is the first demonstration of an association between UFP-related decreased PFT results, worsening of CT findings and elevation of inflammatory cytokines, which may be attributed to high-dose inhalation of UFP of ASD at the workplace.

Comparison of the International Classification of High-resolution Computed Tomography for occupational and environmental respiratory diseases with the International Labor Organization International Classification of Radiographs of Pneumoconiosis

The International Classification of High-resolution Computed Tomography for Occupational and Environmental Respiratory Diseases (ICOERD) has been developed for screening and diagnosis of occupational lung diseases. We evaluated the association of icoerd with the International Labor Organization (ILO) classification and respiratory functions in pneumoconiosis. Chest x-rays of patients with pneumoconiosis were classified with ilo and icoerd using hrct, irregular opacity, pleural pathology, and emphysema was detected in 78, 19, and 53 patients, and using chest x-rays in 47, 4, and 14 patients, respectively. There was a significant correlation between ILO categories and ICOERD grades. There was a negative correlation between ILO categories and FEV1% and FVC%, whereas, ICOERD grades were not correlated with FEV1% and FVC%. HRCT was superior to chest x-rays to detect pneumoconiosis in early stage, but not in evaluating pulmonary functions.

Computed tomography findings of arc-welders' pneumoconiosis: Comparison with silicosis

OBJECTIVE

Arc-welders' pneumoconiosis (AWP) is a less fibrogenic pneumoconiosis with radiographic shadows that can improve after isolation from dusty environments. Therefore, early diagnosis is important. However, the exact role of chest radiograph and computed tomography (CT) for diagnosing AWP is not fully understood. This study was performed to assess the CT appearance of AWP using semi-quantitative methods and to compare the findings with those of silicosis. The profusion of pulmonary abnormality on chest radiograph were also compared with the semi-quantitative CT score.

MATERIALS AND METHODS

Sixty-six patients with clinically diagnosed AWP were included and compared with 33 patients with silicosis. The CT images were interpreted according to the International Classification of HRCT for Occupational and Environmental Respiratory Diseases (ICOERD). Data on the profusion score by chest radiograph were also compared with CT score.

RESULTS

Ill-defined centrilobular nodules, ground-glass opacity (GGO) and centrilobular branching opacity were more frequently observed (p = 0.0031) in AWP, whereas well-defined rounded opacity (p < 0.0001), progressive massive fibrosis (p < 0.0001), and mediastinal lymphadenopathy (p < 0.0001) were more frequently observed in silicosis. Regarding lung nodules, there was a high correlation between the ICOERD and CXR profusion scores in silicosis, but CXR underestimated AWP.

CONCLUSION

Ill-defined centrilobular nodules, GGO and centrilobular branching opacity were more frequently observed in AWP than silicosis. Because these findings are difficult to detect by chest radiograph, CT should be considered for the assessment of patients with suspected AWP.

Modificação do perfil da silicose na mineração subterrânea de ouro em Minas Gerais

Resumo Introdução: Minas Gerais é o estado brasileiro com maior registro de casos de silicose, sendo grande parte proveniente de casuísticas acumuladas das minerações de ouro. Objetivos: descrever e analisar temporalmente a ocorrência de silicose na mineração de ouro identificando fatores ocupacionais relacionados. Métodos: estudo transversal com 1.020 ex-mineiros da região de Nova Lima/MG, avaliados entre 1995 e 2011. Resultados: o diagnóstico de silicose foi confirmado em 19,7% dos avaliados. Nenhum caso da doença foi identificado em indivíduos que trabalharam apenas na superfície. A prevalência no grupo que trabalhou até 5 anos no subterrâneo foi de 3,8% e no grupo com mais de 20 anos de trabalho nesse local foi de 44,2%. Os admitidos para trabalho subterrâneo até 1950 apresentaram prevalência de 57,9%. Entre os admitidos após 1990, não houve registro de casos. Conclusão: verificou-se uma queda expressiva na ocorrência de silicose no período analisado. Uma vez que a doença é sabidamente dose-dependente, é esperado que a diminuição dos níveis de exposição, obtido pelas melhorias dos ambientes ocupacionais, tenha refletido nestes resultados. É fundamental que tais medidas continuem a ser adotadas na mineração e em outros ramos de atividade visando reduzir a ocorrência da doença.

Prevalence and characteristics of COPD among pneumoconiosis patients at an occupational disease prevention institute: a cross-sectional study

BACKGROUND

Pneumoconiosis may play an important role in the development of chronic obstructive pulmonary disease (COPD), and the complication of COPD may impose a heavy burden of illness.

METHODS

The study was conducted in Hunan Province in China from December 1, 2015, to December 1, 2016. Consecutive underground male pneumoconiosis patients employed for at least 1 year were recruited from the Hunan Occupational Disease Prevention Institute. Patient information, respiratory symptoms and clinical data were collected using a structured questionnaire. The diagnosis of COPD were assessed using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Logistic regression analyses were conducted to examine the clinical and demographic risk factors of COPD among pneumoconiosis patients.

RESULTS

The prevalence of COPD in our sample of pneumoconiosis patients was 18.65% (119/638). In pneumoconiosis patients with and without smoking history, the prevalence of COPD was 19.32 and 16.77%. Compared with non-COPD patients, those with COPD are older in age, have longer exposure time, have lower body mass index (BMI), have a higher smoking index and have worse pulmonary function (all p < 0.05). For the five respiratory symptoms (cough, sputum, wheeze, dyspnea, and chest tightness), only the presence of wheeze and the severity scores for wheeze or dyspnea showed significant differences between the COPD and non-COPD groups (p < 0.01). Multivariate logistic regression analysis revealed that advanced pneumoconiosis category, older age and the presence of wheeze symptoms were significant risk factors for the development of COPD among pneumoconiosis patients.

CONCLUSION

Pneumoconiosis patients are at a high risk of COPD, and pneumoconiosis patients with COPD may suffer more severe respiratory symptoms, such as wheeze and dyspnea, than patients without COPD. Advanced pneumoconiosis category, older age and the presence of wheeze symptoms are associated with an increased risk of COPD in pneumoconiosis. We proposed that a routine assessment of lung function is necessary for timely and adequate clinical management.

HO-1 protects smokers exposed to artificial stone dust for pulmonary function tests deterioration

Background: The Heme Oxygenase system, along with its catabolism products, is involved in a variety of crucial physiological functions, including cytoprotection, inflammation, anti-oxidative effects, apoptosis, angiogenesis, and vascular regulation. Objectives: To analyze the Heme Oxygenase -1 (HO-1) mediated effect of mild deterioration of pulmonary function testing (PFT) in exposed artificial stone smoking workers. Methods: One hundred stone workers divided into current smokers, ex-smokers and never smokers underwent Low Resolution Computed Tomography, PFT, induced sputum (IS) Particle Size Distribution (PSD) and Real Time PCR in IS samples. Results: Smoking status had no significant effect on PFT results but it altered the IS differential cell counts. There was significantly less decline in PFT over time for the smokers group. There was a significantly lower fraction of small particles (<2 μm) in the IS of the current smokers group compared to the never- and ex-smokers groups. HO-1 gene expression was higher among smokers compared to never- and ex-smokers groups. A low percentage of small particles (<5 μm) correlated negatively to the percentage of neutrophils and positively to the percentage of macrophages in the sputum of the smokers group. Conclusions: We found significantly lower risk for decreased PFT deterioration among smokers workers exposed to artificial stone dust with higher HO-1 gene expression suggesting a possible protective effect of smoking by the involvement of HO-1 mechanism. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 276-284).

ACR Appropriateness Criteria Review ACR Appropriateness Criteria® Occupational Lung Diseases

Occupational lung disease is a category of disease entities characterized by a reaction of the lung parenchyma to inhaled aerosolized particles found in the environment. This document summarizes the imaging appropriateness data for silicosis, coal worker pneumoconiosis, and asbestosis. The main points of the document are that computed tomography is more sensitive than radiography, computed tomography without contrast generally suffices for evaluation, and fluorodeoxyglucose-positron emission tomography may have utility in patients with mesothelioma. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review includes an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

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.

Silicosis

Silicosis is a fibrotic lung disease caused by inhalation of free crystalline silicon dioxide or silica. Occupational exposure to respirable crystalline silica dust particles occurs in many industries. Phagocytosis of crystalline silica in the lung causes lysosomal damage, activating the NALP3 inflammasome and triggering the inflammatory cascade with subsequent fibrosis. Impairment of lung function increases with disease progression, even after the patient is no longer exposed. Diagnosis of silicosis needs carefully documented records of occupational exposure and radiological features, with exclusion of other competing diagnoses. Mycobacterial diseases, airway obstruction, and lung cancer are associated with silica dust exposure. As yet, no curative treatment exists, but comprehensive management strategies help to improve quality of life and slow deterioration. Further efforts are needed for recognition and control of silica hazards, especially in developing countries.

Cavitated conglomerate mass in silicosis indicating associated tuberculosis

Silicosis is the most common occupational lung disease worldwide. It leads to respiratory impairment and may have associated infections that decrease pulmonary function. We describe the case of a 55-year-old man with chronic silicosis who presented with hemoptysis and a cavitated conglomerate mass. The final diagnosis was silicotuberculosis.

MDCT findings of denim-sandblasting-induced silicosis: a cross-sectional study

BACKGROUND

Denim sandblasting is as a novel cause of silicosis in Turkey, with reports of a recent increase in cases and fatal outcomes. We aimed to describe the radiological features of patients exposed to silica during denim sandblasting and define factors related to the development of silicosis.

METHODS

Sixty consecutive men with a history of exposure to silica during denim sandblasting were recruited. All CT examinations were performed using a 64-row multi-detector CT (MDCT). The nodules were qualitatively and semi-quantitatively analyzed by grading nodular profusion (NP) on CT images.

RESULTS

Silicosis was diagnosed radiologically in 73.3% of patients (44 of 60). The latency period (the time between initial exposure and radiological imaging) and duration of silica exposure was longer in patients diagnosed with silicosis than in those without silicosis (p < 0.05). Nodules were present in all cases with centrilobular type as the commonest (63.6%). All cases of silicosis were clinically classified as accelerated and 11.4% had progressive massive fibrosis (PMF). Mild NP lesions were the most prevalent in all six zones of the lung. The NP score was significantly correlated with the duration of silica exposure, the latency period, presence of PMF, and pleural thickening. Enlarged lymphadenopathy was present in 45.5% of patients.

CONCLUSIONS

The duration of exposure and the latency period are important for development of silicosis in denim sandblasters. MDCT is a useful tool in detecting findings of silicosis in workers who has silica exposure.

High-resolution computed tomography in silicosis: correlation with chest radiography and pulmonary function tests

OBJECTIVE

To correlate tomographic findings with pulmonary function findings, as well as to compare chest X-ray findings with high resolution computed tomography (HRCT) findings, in patients with silicosis.

METHODS

A cross-sectional study was conducted in 44 non-smoking patients without a history of tuberculosis. Chest X-ray findings were classified according to the International Labour Organization recommendations. Using a semiquantitative system, the following HRCT findings were measured: the full extent of pulmonary involvement; parenchymal opacities; and emphysema. Spirometry and forced oscillation were performed. Pulmonary volumes were evaluated using the helium dilution method, and diffusing capacity of the lung for carbon monoxide (DLCO) was assessed.

RESULTS

Of the 44 patients studied, 41 were male. The mean age was 48.4 years. There were 4 patients who were classified as category 0 based on X-ray findings and as category 1 based on HRCT findings. Using HRCT scans, we identified progressive massive fibrosis in 33 patients, compared with only 23 patients when X-rays were used. Opacity score was found to correlate most closely with airflow, DLCO and compliance. Emphysema score correlated inversely with volume, DLCO and airflow. In this sample of patients presenting a predominance of large opacities (75% of the individuals), the deterioration of pulmonary function was associated with the extent of structural changes.

CONCLUSIONS

In the early detection of silicosis and the identification of progressive massive fibrosis, HRCT scans are superior to X-rays.

CT findings in silicosis due to denim sandblasting

The purpose of this study was to describe the findings of CT performed on denim sandblasters with silicosis. Fifty consecutive male patients with silicosis were evaluated. Their clinical data and pulmonary function tests (PFT) were obtained. The CT findings were recorded and the correlations between CT nodular profusion score and the other parameters were assessed. The diagnoses of the patients were classified as accelerated silicosis (n = 43) and acute silicosis (n = 7). The most common CT finding was centrilobular nodules. Twenty-three patients had complicated silicosis based on pleural involvement and presence of progressive massive fibrosis (PMF). Lymphadenopathy (LAP) was positive in 50% of the patients, with calcification in 24%. The CT grade was highly correlated with the clinical data such as exposure duration and PFT. Our findings suggest that the clinical manifestation of silicosis in denim sandblasters is severe. Although the duration of exposure is shorter the rate of complicated silicosis patients with pleural involvement was unexpectedly higher in the cases. Because the most common radiological appearance was nodules and the CT grading of the nodules was highly correlated with the clinical data, nodule grading may be used in the management of such cases.

An old threat in a new setting: High prevalence of silicosis among jewelry workers

BACKGROUND

Silicosis is caused by inhaling free crystalline silica. Few case reports have addressed the risk of silicosis in the jewelry trade where chalk molds containing a high percentage of silica are used in casting. We conducted a cross-sectional study involving 100 goldsmiths exposed to silica.

METHODS

All workers replied to a questionnaire and underwent a clinical examination, pulmonary function tests, a chest X-ray and a high-resolution CT scan.

RESULTS

High-resolution CT visualized signs of silicosis in 23 cases, confirmed by standard chest X-rays in 10. In the 23 workers with CT evidence of silicosis Total Lung Capacity, FEV1 and the Lung Diffusing Capacity did not differ from the workers without the disease. Pulmonary function tests did not correlate with silica exposure.

CONCLUSION

In this study we demonstrate that use of chalk molds in casting in jewelry causes silicosis. The composition of the dust could be responsible of the high prevalence observed.

Conglomerated masses of silicosis in sandblasters: High-resolution CT findings

The purpose of this study was to describe the high-resolution CT aspects of the silicosis and progressive massive fibrosis in sandblasters. The study was performed with 25 consecutive patients with silicosis and large opacities on chest radiography according to the International Labor Office (ILO) classification of pneumoconiosis. All patients presented with conglomerate masses involving the upper lobes, and in 92% of the cases the lesions were located in the posterior region of the lungs. The masses frequently showed nodular contour (76%), air bronchograms (76%), foci of calcification (72%), paracicatricial emphysema (72%), and adjacent pleural thickening (92%). Calcification of hilar or mediastinal lymph nodes (96%), mainly of the egg-shell type (56%), was also a common finding. In conclusion, in this specific group of patients, the sandblasters, the high-resolution CT demonstrated conglomerated masses with nodular contour, air bronchograms and foci of calcification, which were distributed mainly in the posterior region of the upper lobes. Calcification of hilar or mediastinal lymph nodes was also commonly seen.

Pictorial Essay: Multinodular Disease

The evaluation of patients presenting with multinodular pulmonary disease provides an important clinical challenge for physicians. The differential diagnosis includes an extensive list of benign and malignant processes making the management of these cases frequently problematic. With the introduction of high-resolution CT (HRCT) scanning, the ability to assess various patterns of diffuse multinodular disease has evolved into an essential part of the diagnostic process. The purpose of this article is to develop an approach to the diagnosis of multinodular parenchymal disease using HRCT scan pattern recognition as a point of departure.

Radiological Findings, Pulmonary Function and Dyspnea in Underground Coal Miners

BACKGROUND

Respiratory disability induced by dust exposure in coal workers is assessed by pulmonary function tests and radiological evidence of pneumoconiosis. High-resolution computed tomography (HR-CT) improves the visibility of tissue changes, but the value of the findings for the clinical evaluation is controversial.

OBJECTIVES

It was the aim of this study to evaluate the correlation between the International Labour Office (ILO) classification and the degree of emphysema in HR-CT with self-reported dyspnea and pulmonary function tests including diffusion capacity for CO (DL,CO).

METHODS

We investigated 87 coal miners (aged 67+/-6 years), having worked underground for 26+/-9 years, with pulmonary function tests and HR-CT. Univariate associations were tested with correlation coefficients, and multivariable analyses used a stepwise forward regression model.

RESULTS

No aspect of the ILO classification showed a univariate correlation with dyspnea or forced expiratory flow in 1 s (FEV1). Emphysema CT score was strongly associated with DL,CO (rs=-0.40; p<0.001) and FEV1/maximal vital capacity (r=-0.38; p<0.001) in univariate analysis, but not with the clinical grade of dyspnea (r=-0.14; p=0.256). CT emphysema score but not ILO classification was associated with FEV1 in multivariable analyses (rs=-0.37; p<0.001). Dyspnea was best approximated by DL,CO (r=-0.312; p=0.008).

CONCLUSION

The clinical grade of breathlessness was best approximated by DL,CO. HR-CT showed a good association with expiratory flow limitation. ILO classification of the chest radiograph may be a marker of exposure but conveys little information about the degree of respiratory impairment.

Silicosis: Expiratory Thin-Section CT Assessment of Airway Obstruction

PURPOSE

To prospectively evaluate if findings on paired inspiratory and expiratory thin-section computed tomographic (CT) scans in patients with silicosis correlate with pulmonary function test results.

MATERIALS AND METHODS

Institutional review board approval and patient consent were obtained. Thirty-seven men (mean age, 71 years; range, 53-88 years) with silicosis were included. All patients had undergone inspiratory and expiratory thin-section CT and spirometry. Silicotic nodules, large opacity, emphysema, reticular opacities, bronchiectasis, and air trapping were graded subjectively on CT images. Emphysema was quantified on these images with built-in software. CT numbers were correlated with spirometric findings by using Spearman rank correlation analyses. Ten healthy volunteers (three men and seven women; mean age, 58 years) served as control subjects.

RESULTS

After exclusion of three patients with inadequate image quality, 34 patients (mean age, 70 years; range, 53-88 years) were enrolled in the study group. Spirometric values did not differ significantly between patients with simple (n = 20) and patients with complicated (n = 14) silicosis but were significantly lower in patients than in control subjects. CT findings included air trapping (n = 33), emphysema (n = 26), nodules (n = 32), bronchiectasis (n = 22), large opacity (n = 19), and reticulation (n = 5). The extent of both air trapping and emphysema correlated negatively with spirometric values; the air trapping score showed the strongest correlation (ratio of forced expiratory volume in 1 second to forced vital capacity [FVC]: rho = -0.632, P < .001; forced expiratory flow at 50% of the FVC: rho = -0.576, P = .001). Silicotic nodule, large opacity, and bronchiectasis scores did not correlate with obstructive functional impairments.

CONCLUSION

In comparison with the spirometric value, the extent of air trapping proved the best CT index in the assessment of obstructive derangement in workers with exposure to silica dust.

Pleural Disease in Silicosis: Pleural Thickening, Effusion, and Invagination

PURPOSE

To retrospectively evaluate pleural disease on images from patients with autopsy-proved silicosis.

MATERIALS AND METHODS

The study had institutional review board approval, and informed consent from relatives of diseased subjects was waived. Lung specimens were obtained at autopsy in 110 men (mean age, 72 years) who had been followed up radiologically for a mean of 14.8 years. Computed tomographic (CT) scans obtained within 2 years before death were examined for presence of pleural thickening; shape, composition, size, and subpleural location of progressive massive fibrosis (PMF); and pleural invagination (bandlike structure between lesion and pleura). Lung specimens were reviewed and compared with CT findings. Serial chest radiographs and CT scans were reviewed for presence of pleural effusion. Association between radiographic findings and pleural invagination was analyzed with chi2 and Student t tests. Multiple logistic regression analysis was used to find predictive variables for pleural invagination.

RESULTS

Pleural effusion was found in 12 (11%) patients at chest radiography and CT, and thickening was found in 64 (58%) patients at CT; the latter finding was significantly more frequent with complicated silicosis (P < .001). At CT, 128 PMF lesions were seen, 39 (30%) of which showed pleural invagination; CT scans showed pleural thickening in 36 (92%) of these 39 lesions. In 17 (44%) PMF lesions, CT scans depicted a bandlike structure that was pathologically confirmed to represent invaginated pleura in all cases. Pathologic presence of invagination was significantly associated with pleural thickening (P < .001), ipsilateral pleural effusion (P < .01), interstitial fibrosis (P < .05), and the nearness of PMF to the pleura (P < .005). Multiple logistic regression analysis showed that pleural thickening (odds ratio, 62.51; 95% confidence interval [CI]: 5.564, 70.2) and pleural effusion (odds ratio, 25.865; 95% CI: 1.992, 335.8) were significant CT variables associated with presence of pathologic pleural invagination (P = .001 and .013, respectively). Five PMF lesions had radiographic features of rounded atelectasis.

CONCLUSION

Various pleural abnormalities can occur in silicosis, especially in advanced disease.

High-resolution CT in silicosis: correlation with radiographic findings and functional impairment

OBJECTIVE

To assess high-resolution computed tomography (HRCT) findings in silicosis and to better define the role of HRCT in early detection of parenchymal abnormalities in silica-exposed workers.

METHODS

Forty-one stone carvers were evaluated with chest radiographs (CR), HRCT, and pulmonary function tests (PFT). Inter-reader agreement was calculated using the kappa statistic (k). Correlation between radiographic and HRCT profusion scores and PFT was assessed using the Spearman correlation coefficient.

RESULTS

The most common HRCT findings were branching centrilobular structures, seen in 28/41 workers (68.3%). Nodules consistent with silicosis were detected in 53.7% workers on CR and in 56.1% workers on HRCT. Inter-reader agreement for diagnosis of silicosis was better on HRCT (k = 0.84) than on CR (k = 0.54). Small opacity profusion on HRCT correlated inversely with total lung capacity and FVC%.

CONCLUSION

Profusion of opacities on HRCT correlates with functional impairment. The presence of branching centrilobular structures may be helpful in early recognition of silicosis.

Occupational interstitial lung disease

Occupational interstitial lung diseases are a diverse group of disorders of varied cause. Occupational causes account for a significant portion of all interstitial lung diseases, and new causes continue to be described. Although some are diseases of antiquity, they continue to occur in the workplace and often are misdiagnosed as "idiopathic" when physicians miss the connection to past-inhaled exposures. All of these diseases are preventable with reduction or elimination of workplace exposure. This article reviews the spectrum of diseases caused by exposure to metal dust and fumes, inorganic fibers, and nonfibrous inorganic dust. It also details an approach to the diagnosis, evaluation, and management of this group of illnesses.