Identification of rounded atelectasis in workers exposed to asbestos by contrast helical computed tomography

Rounded atelectasis (RA) is a benign and unusual form of subpleural lung collapse that has been described mostly in asbestos-exposed workers. This form of atelectasis manifests as a lung nodule and can be confused with bronchogenic carcinoma upon conventional radiologic examination. The objective of the present study was to evaluate the variation in contrast uptake in computed tomography for the identification of asbestos-related RA in Brazil. Between January 1998 and December 2000, high-resolution computed tomography (HRCT) was performed in 1658 asbestos-exposed workers. The diagnosis was made in nine patients based on a history of prior asbestos exposure, the presence of characteristic (HRCT) findings and lesions unchanged in size over 2 years or more. In three of them the diagnosis was confirmed during surgery. The dynamic contrast enhancement study was modified to evaluate nodules and pulmonary masses. All nine patients with RA received iodide contrast according to weight. The average enhancement after iodide contrast was infused, reported as Hounsfield units (HU), increased from 62.5 ± 9.7 to 125.4 ± 20.7 (P < 0.05), with a mean enhancement of 62.5 ± 19.7 (range 40 to 89) and with a uniform dense opacification. In conclusion, in this study all patients with RA showed contrast enhancement with uniform dense opacification. The main clinical implication of this finding is that this procedure does not permit differentiation between RA and malignant pulmonary neoplasm

Thin-section CT abnormalities and pulmonary gas exchange impairment in workers exposed to asbestos

PURPOSE: To evaluate the relationship between abnormalities at thin-section computed tomography (CT) and indexes of pulmonary gas exchange impairment at rest and during moderate exercise in workers exposed to asbestos. MATERIALS AND METHODS: Eighty-two workers with long-term exposure to asbestos and abnormal thin-section CT findings underwent respiratory physiologic measurements at rest (lung diffusing capacity, DLCO) and during exercise (oxygen uptake-corrected alveolar-arterial pressure difference for oxygen, DeltaP[A-a]O-2/VO2). CT results were compared with physiologic measurements of impairment in gas exchange (DLCO 20 mm Hg (.) L (.) min(-1)). The CT findings were divided into five categories by using a previously described method. Odds ratios and 95% Cls for gas exchange defects were calculated for patients grouped according to CT findings. Logistic regression analysis was performed with gas exchange as the dependent response and CT abnormalities as independent variables. RESULTS: A significant association was found between extent of disease at CT and impairment of gas exchange (P .05). CONCLUSION: Thin-section CT grading of interstitial lung disease is useful in assessing the likelihood of pulmonary gas exchange impairment at rest (DLCO) and during exercise (DeltaP[A-a]O-2/VO2) in workers with long-term asbestos exposure.2321667

Non-malignant consequences of decreasing asbestos exposure in the Brazil chrysotile mines and mills

Aims: To investigate the consequences of improvement in the workplace environment over six decades (1940–96) in asbestos miners and millers from a developing country (Brazil). Methods: A total of 3634 Brazilian workers with at least one year of exposure completed a respiratory symptoms questionnaire, chest radiography, and a spirometric evaluation. The study population was separated into three groups whose working conditions improved over time: group I (1940–66, n = 180), group II (1967–76, n = 1317), and group III (1977–96, n = 2137). Results: Respiratory symptoms were significantly related to spirometric abnormalities, smoking, and latency time. Breathlessness, in particular, was also associated with age, pleural abnormality and increased cumulative exposure to asbestos fibres. The odds ratios (OR) for parenchymal and/or non-malignant pleural disease were significantly lower in groups II and III compared to group I subjects (0.29 (0.12–0.69) and 0.19 (0.08–0.45), respectively), independent of age and smoking status. Similar results were found when groups were compared at equivalent latency times (groups I v II: 30–45 years; groups II v III: 20–25 years). Ageing, dyspnoea, past and current smoking, and radiographic abnormalities were associated with ventilatory impairment. Lower spirometric values were found in groups I and II compared to group III: lung function values were also lower in higher quartiles of latency and of cumulative exposure in these subjects. Conclusions: Progressive improvement in occupational hygiene in a developing country is likely to reduce the risk of non-malignant consequences of dust inhalation in asbestos miners and millers