Progression from near-normal to end-stage lungs in chronic interstitial pneumonia related to silica exposure: long-term CT observations.

OBJECTIVE: The objective of our study was to evaluate serial CT changes from normal or near-normal lungs to honeycomb lungs in dust-exposed patients who developed chronic interstitial pneumonia. MATERIALS AND METHODS: From the records of the national hospital for pneumoconiosis, we retrospectively identified patients with chronic interstitial pneumonia who were under surveillance between 1986 and 2006. All patients occasionally underwent chest CT for evaluation of silicosis or exclusion of possible complications. Patients were included in this study only if the initial CT examination did not show obvious chronic interstitial pneumonia. Fourteen patients (all men; median age at initial CT, 58 years) were identified as meeting the inclusion criterion. Two independent reviewers randomly reviewed the CT scans of the study patients to score the extent of ground-glass opacity, reticulation, and honeycombing; to provide a summation of all interstitial opacities (fibrosis score); and to assess coarseness. RESULTS: Autopsy findings were available for eight of the 14 patients and confirmed the usual interstitial pneumonia (UIP) pattern seen on CT. The median follow-up period was 15.4 years, and none of the patients experienced acute exacerbation. One hundred two CT scans were reviewed. The earliest CT abnormalities included faint ground-glass opacity limited to the lung bases (n = 13) or only coarse reticular opacity (n = 1). In 13 patients, fibrosis and coarseness progressed linearly, whereas the other opacities did not. The annual increase of the fibrosis score and coarseness ranged from 0.306% to 4.633% and 0.179 to 0.479, respectively. Honeycombing developed in all patients over a median period of 12.1 years (range, 3.7-19.1 years). CONCLUSION: The coarseness best represented the progression of chronic interstitial pneumonia in dust-exposed patients. The earliest CT finding of a UIP pattern in dust-exposed patients was indistinguishable from other types of chronic interstitial pneumonia.

Assessment of physicians' proficiency in reading chest radiographs for pneumoconiosis, based on a 60-film examination set with two factors constituting eight indices.

Two hundred and thirty-three individuals read chest x-ray images (CXR) in the Asian Intensive Reader of Pneumoconiosis (AIR Pneumo) workshop. Their proficiency in reading CXR for pneumoconiosis was calculated using eight indices (X1-X8), as follows: sensitivity (X1) and specificity (X2) for pneumoconiosis; sensitivity (X3) and specificity (X4) for large opacities; sensitivity (X5) and specificity (X6) for pleural plaques; profusion increment consistency (X7); and consistency for shape differentiation (X8). For these eight indices, one-way analysis of variance (ANOVA) and Scheffe's multiple comparison were conducted on six groups, based on the participants' specialty: radiology, respiratory medicine, industrial medicine, public health, general internal medicine, and miscellaneous physicians. Our analysis revealed that radiologists had a significant difference in the mean scores of X3, X5, and X8, compared with those of all groups, excluding radiologists. In the factor analysis, X1, X3, X5, X7, and X8 constituted Factor 1, and X2, X4, and X6 constituted Factor 2. With regard to the factor scores of the six participant groups, the mean scores of Factor 1 of the radiologists were significantly higher than those of all groups, excluding radiologists. The two factors and the eight indices may be used to appropriately assess specialists' proficiency in reading CXR.

Chronic interstitial pneumonia in silicosis and mix-dust pneumoconiosis: its prevalence and comparison of CT findings with idiopathic pulmonary fibrosis.

BACKGROUND: Increased prevalence of chronic interstitial pneumonia (CIP) is reported in dust-exposed subjects. We investigated the prevalence of CIP in silicosis and mixed-dust pneumoconiosis and sought morphologic differences of CIP between the pneumoconiosis and idiopathic pulmonary fibrosis (IPF). METHODS: We reviewed CT scans of 243 silicosis and mixed-dust pneumoconiosis patients to identify any cases of parenchymal lung lesions showing a CIP pattern, and compared the CT findings with those of 62 patients with IPF. Two observers independently scored CT images and classified the CT pattern as typical or not typical for IPF. Differences were sought between the groups using a nonparametric test, Fisher exact test, and a logistic regression analysis. A radiopathologic correlation was performed in 11 pneumoconiosis patients. RESULTS: Twenty-eight patients (11.5%) showed CIP on CT. Seven patients (25%) showed a pattern not typical of IPF, while the remaining patients showed a pattern typical of IPF, 11 of which were confirmed pathologically. The extent of fibrosis did not differ between the groups; however, patients with pneumoconiosis showed less traction bronchiectasis (odds ratio [OR], 0.19; 95% confidence interval [CI], 0.08 to 0.48; p < 0.001), more subpleural homogeneous attenuation (OR, 2.56; 95% CI, 1.55 to 4.23; p < 0.001), and fibrosis was more randomly distributed (OR, 315.38; 95% CI, 4.68 to 21244.63; p = 0.007). Pathologically, subpleural homogeneous attenuation corresponded to dense fibrosis often with abundant silicotic nodules. CONCLUSIONS: Prevalence of CIP in pneumoconiosis was approximately 12% on CT. One fourth of patients showed an atypical IPF pattern, and the others showed a typical IPF pattern.

A flat-panel detector digital radiography and a storage phosphor computed radiography: screening for pneumoconioses.

Storage phosphor computed radiography (SR) and flat-panel detector (FPD) radiography are two types of digital X-ray utilizing different techniques. We compared these two techniques with conventional analogue chest radiograph (AR) among pneumoconiotic patients and healthy controls. Thirty individuals consisting of 20 silica-exposed ex-workers and 10 healthy controls without occupational exposure to any mineral dust were examined with chest X-ray by AR, SR and FPD. Three occupational physicians, including one NIOSH B reader, assessed the digital and conventional radiographs by the side-by-side method according to the ILO 2000 International Classification of Radiograph of Pneumoconioses (ILO/ICRP). No significant difference was shown between the subjective film qualities by AR and FPD. Inter-reader agreement of the profusion of small opacities on radiographs was high in the order of SR (kappa=0.64), FPD (kappa=0.62), and AR (kappa=0.55). The profusions of small opacity for AR and FPD by the 12-point scaled profusion of ILO/ICRP did not show a statistically significant difference, but those for AR and SR showed a significant difference. The areas under the receiver operator curves (ROC) using clinical diagnosis by a pulmonologist as the reference showed no statistically significant difference among the three radiographic techniques. FPD gives image quality as good as that of AR, and it has acceptable agreement with AR in small profusion categories, which consequently assures its application to pneumoconiosis screening. SR showed less profusion than FPD and AR, which can be fixed with image modification.

Proposed criteria for mixed-dust pneumoconiosis: definition, descriptions, and guidelines for pathologic diagnosis and clinical correlation.

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.

The 60-film set with 8-index for examining physicians' proficiency in reading pneumoconiosis chest X-rays.

The 60-film set was developed by experts (Expert Group) for examining 8 indices: sensitivity (X(1)) and specificity (X(2)) for pneumoconiosis, sensitivity(X(3)) and specificity for (X(4)) large opacities, sensitivity (X(5)) and specificity (X(6)) for pleural plaque, profusion increment consistency for small opacities (X(7)), and shape differentiation for small opacities (X(8)) of physicians' reading skills on pneumoconiosis X-ray according to ILO 2000 Classification. The aim of this study was to assess the appropriateness of the exam film set for evaluating physicians' reading skills. 29 physicians (A1-Group) and 24 physicians (A2-Group) attended the 1st and 2nd "Asian Intensive Reader of Pneumoconioses" (AIR Pneumo) training course, respectively, and 22 physicians (B-Group) attended Brazilian training course. After training, they took examination of reading 60-film exam set. The examinees' reading results in terms of 8 indices were compared between the examinee groups and the Expert Group by parametric unpaired t-test. The Examinee Group consisting of A1-Group, A2-Group and B-Group was inferior to the Expert Group in all indices. There was no significant difference for X(7) of A1-Group, X(7) and X(8) of A2-Group (p>0.05) compared with the Expert Group. There was a significant difference in X(8) at p<0.05 between A1-Group and A2-Group, in X(3) at p<0.05 between A1-Group and B-Group, in both X(1) and in X(3) at p<0.05 between A2-Group and B-Group. Accordingly, the 60-film set providing 8 indices designed might be a good method for evaluation of the physicians' reading proficiency at different training settings.

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.

Effect of a two-hour training on physicians' skill in interpreting Pneumoconiotic chest radiographs.

OBJECTIVE: Occupational lung diseases have specific radiographic manifestations not always well known by physicians. In Japan, asbestos-related diseases became a public health concern after the "Kubota Shock", when a number of workers and residents living nearby a manufacturer of asbestos-made ducts developed mesothelioma caused by asbestos exposure. This preliminary intervention trial evaluated the effect of two-hour training on inexperienced physicians' skill in interpreting pneumoconiotic chest radiographs. METHODS: One hundred-two Japanese physicians participated in two reading-tests, using 12 radiographs, before and after the two-hour training with ILO/ICRP and Japan Pneumoconioses Study Group (JPSG) reading materials. Physicians had to check for the presence or absence of small opacity and pleural plaque consistent with pneumoconiosis. Sensitivity and specificity equal or greater than 70% were considered good, 50 to 69% acceptable and less than 50%, poor. RESULTS: Post-training improvements in physicians' skills were seen. For small opacity, there was an increase in the proportion of physicians with good specificity, from 42% to 60%. For pleural plaque, the proportion of physicians with good specificity and good sensitivity increased, from 60% to 67% and from 18% to 25%, respectively. Also, significant improvements were observed in overall sensitivity for pleural plaque, from 46% to 60% (p<0.0001), and specificity for small opacity, from 65% to 73% (p<0.0001). CONCLUSIONS: This study showed that two-hour participatory training may enhance physicians' skill in interpreting pneumoconiotic chest radiographs. There are countries without any pneumoconiosis screening program despite the WHO/ILO call for worldwide cooperation in eliminating it. Although the two-hour course cannot replace the five-day ILO workshop, such a program would be useful in areas with environmental or occupational exposure to dust.

Pulmonary malignancy in silicosis: factors associated with radiographic detection.

The aim was to assess radiographic features of pulmonary malignancies in silicosis and to reveal confounding factors in their detection. A total of 501 silicosis patients were followed up between 1982 and 2003. Sixty pulmonary malignancies were pathologically confirmed in 54 (10.8%) patients. Two radiologists reviewed serial radiographs of these patients to determine radiographic features of tumor (size, margin, nodule or consolidation, localization, overlying structures) and silicosis (profusion of pneumoconiotic opacities, progressive massive fibrosis (PMF), hilar lymphadenopathy). Eleven tumors were radiographically negative. Forty-nine tumors were retrospectively visible with radiograph. Of these, 15 tumors were clinically detected with radiograph, but 25 were missed. The remaining nine tumors became radiographically positive after positive sputum cytology. There were no differences between missed and detected nodules in terms of radiographic findings. The mean tumor size was 30mm (range: 15-90mm) and was significantly larger in patients with PMF or hilar lymphadenopathy than in those without (35mm vs. 24mm, p=0.006; 33mm vs. 24mm, p=0.038, respectively). This was correlated with background profusion of small pneumoconiotic opacities (r=0.433, p=0.024). Retrospective reading tests by three radiologists showed correct localization of tumor in 75%, however, the correct diagnosis with a high confidence was reached in only 54%. In conclusion, radiographic detection of malignancy in silicosis proved a difficult task and no single radiographic finding was found to be associated with missing the tumor. The presence of PMF, hilar lymphadenopathy and profusion of small pneumoconiotic nodules affected tumor size at detection.

Reliability of the proposed international classification of high-resolution computed tomography for occupational and environmental respiratory diseases.

PURPOSE: We have developed a classification of high-resolution computed tomography (HRCT) images for screening, surveillance and epidemiological studies of respiratory diseases caused by occupational and environmental factors. The proposed classification consists of three parts: a guideline explaining the elements of the classification scheme, a reading sheet, and reference films to aid in assessing thin-section CT films. We assessed the reliability of the proposed classification system by blinded, independent trial reading. MATERIALS AND METHODS: Seven independent radiologists and pulmonologists performed a trial reading to measure the reliability of the classification system using HRCT films from 27 pneumoconiosis patients and 7 normal controls. RESULTS: The agreement was moderate to good for rounded opacities (weighted kappa=0.68 and 0.64), irregular opacities (0.59, 0.48), honeycombing (0.65, 0.47), emphysema (0.76, 0.62) and large opacities (0.48, 0.52). Ground glass opacities (0.16, 0.20) showed poor to fair agreement. Intra-reader agreement of each of the seven readers was moderate to good (mean: weighted kappa=0.52-0.80) for parenchymal findings, but the agreement was relatively low (mean weighted kappa=0.52) for ground glass opacities. CONCLUSION: The proposed classification is able to describe early dust-related fibrotic changes and provide a semi-quantitative description of the HRCT features of major fibrotic changes in the parenchyma and pleura. Reliability, as measured by inter-reader agreement, was satisfactory.

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.

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.

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.

Computed tomography findings of Caplan syndrome.

We report a case of Caplan syndrome complicated with tuberculosis, which was clinically followed up for 18 years and underwent autopsy. Initial chest radiograph showed 2 large nodules against the background of smaller pneumoconiotic nodules. One of the large nodules showed cavitation during follow-up. Computed tomography (CT) was helpful in identifying calcification in another large nodule. Autopsy confirmed the 2 large nodules as burned-out rheumatoid nodules and revealed additional rheumatoid nodules that were indistinguishable from silicotic nodules by CT.