Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests.

Abstract

The lungs of 50 symptom free workers exposed to amosite and with normal pulmonary function tests were examined by high resolution computed tomography (HRCT). Twenty five had normal standard chest radiographs whereas the other 25 had radiographs interpreted as near normal (International Labour Office profusion score <01 or suspected pleural plaques). In 13 of the workers the results of HRCT were negative; in 22 pleural plaques were found, in five there was only parenchymal involvement, and 10 had both pleural and parenchymal changes. The mean duration of exposure to amosite was significantly longer for the subjects with parenchymal signs than for those with normal parenchyma and for the workers with pleural plaques than for those with normal pleura and lung parenchyma. The prevalence of identified pleural and parenchymal abnormalities in the 50 workers was also significantly higher than in a reference group without exposure to asbestos. It is concluded that HRCT may detect initial lung and pleural involvement in symptom free workers exposed to amosite and the mean duration of exposure is longer for subjects with parenchymal or pleural involvement.(Occup Environ Med 1994;51:239-243) Postgraduate Occupational

Asbestosis, pleural plaques and diffuse pleural thickening: three distinct benign responses to asbestos exposure

“…Previously radiographic and CT studies reported that unilateral pleural plaques were not infrequent [38,39]. In contrast to these studies, we did not observe any side predominance, but it should be remembered that workers with bilateral calcified pleural plaques visible on the chest radiograph were not referred for CT scans and, therefore, a selection bias existed.…”

“…In contrast to these studies, we did not observe any side predominance, but it should be remembered that workers with bilateral calcified pleural plaques visible on the chest radiograph were not referred for CT scans and, therefore, a selection bias existed. As far as we know, the leftsided predominance for the presence as well as for the extent of asbestos-related pleural disease has been reported in radiographic studies [39,40], but the only CT study reporting unilateral plaques did not investigate their side predominance [38]. In contrast to pleural plaques, diffuse pleural thickening, parenchymal bands and rounded atelectasis were bilateral in only a minority of the subjects included in the present study.…”

Factors associated with early-stage pulmonary fibrosis as determined by high-resolution computed tomography among persons occupationally exposed to asbestos

“…Whereas established asbestosis has been reported to be associated with respiratory functional impairment mainly of the restrictive type (3,12,22), several authors have described the presence of interstitial abnormalities on HRCT, consistent with early-stage asbestosis, in asymptomatic participants without any functional or Xray abnormalities (7,9). These findings suggest that early-stage HRCT abnormalities might precede functional impairment.…”

“…Systematic use of HRCT for cohorts of people who have been exposed to asbestos revealed interstitial abnormalities consistent with asbestosis in a sizeable fraction of the asymptomatic persons whose posteroanterior chest X-rays (7)(8)(9) or pulmonary function (7,9) were considered normal. As a result, systematic HRCT scanning with a 6-year periodicity was recommended recently in France for the diagnosis of asbestosis for people who are over 50 years of age and have had high occupational exposure to asbestos (10).…”

Are pleural plaques an appropriate endpoint for risk analyses?

“…MRI is much less sensitive than CT (Evans & Gleeson, 2004). Most frequently, pleural plaques are diagnosed using radiographic methods including CXR or CT. Use of CT scans increases both sensitivity and specificity compared to standard CXR (Al Jarad et al, 1991;Neri et al, 1994;O'Reilley et al, 2007;Roach et al, 2002) but results from these two methods are correlated (Suganuma et al, 2001). High-resolution computed tomography (HRCT) is superior to CT (Lynch et al, 1989).…”