Thin-Section CT Abnormalities and Pulmonary Gas Exchange Impairment in Workers Exposed to Asbestos

doi:10.1148/radiol.2321030392

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Thoracic Imaging

Thin-Section CT Abnormalities and Pulmonary Gas Exchange Impairment in Workers Exposed to Asbestos¹

Andrea Sette, MD, PhD, J. Alberto Neder, MD, PhD, Luiz E. Nery, MD, PhD, Jorge Kavakama, MD, Reinaldo T. Rodrigues, MD, Mario Terra-Filho, MD, PhD, Sandra Guimarães, MD, PhD, Ericson Bagatin, MD, PhD and Nestor Müller, MD, PhD

¹ From the Pulmonary Function and Clinical Exercise Physiology Unit, Div of Respiratory Diseases (A.S., J.A.N., L.E.N., S.G.), and Dept of Radiology (R.T.R.), Federal Univ of São Paulo, Rua Professor Francisco de Castro 54, Vila Clementino, CEP 04020–050, São Paulo, Brazil; Occupational Health Service, State Univ of Campinas, São Paulo, Brazil (E.B.); Div of Respiratory Diseases, Univ of São Paulo, Brazil (J.K., M.T.F.); and Dept of Radiology, Vancouver General Hospital, BC, Canada (N.M.). Received Mar 17, 2003; revision requested May 30; final revision received Oct 8; accepted Nov 20. Supported in part by a research grant from FAPESP-Brazil (No. 96–10415-6). A.S. supported by a fellowship grant from CNPq-Brazil. S.G. supported by a fellowship grant from FAPESP-Brazil. Address correspondence to J.A.N. (e-mail: albneder@pneumo.epm.br).

PURPOSE: To evaluate the relationship between abnormalitiesat thin-section computed tomography (CT) and indexes of pulmonarygas exchange impairment at rest and during moderate exercisein workers exposed to asbestos.

MATERIALS AND METHODS: Eighty-two workers with long-term exposureto asbestos and abnormal thin-section CT findings underwentrespiratory physiologic measurements at rest (lung diffusingcapacity, DLCO) and during exercise (oxygen uptake–correctedalveolar-arterial pressure difference for oxygen, ${Delta}$ P[A-a]O₂/VO₂).CT results were compared with physiologic measurements of impairmentin gas exchange (DLCO < 70% predicted value and/or ${Delta}$ P[A-a]O₂/VO₂> 20 mm Hg · L · min^–1). The CT findingswere divided into five categories by using a previously describedmethod. Odds ratios and 95% CIs for gas exchange defects werecalculated for patients grouped according to CT findings. Logisticregression analysis was performed with gas exchange as the dependentresponse and CT abnormalities as independent variables.

RESULTS: A significant association was found between extentof disease at CT and impairment of gas exchange (P < .01).Probability of functional impairment was increased with multifocal(class II) and diffuse (class III) CT abnormalities, particularlywhen several lesion types were found concomitantly. Logisticregression analysis demonstrated significant association ofparenchymal bands (odds ratio, 6.20; 95% CI: 1.99, 19.22) andsubpleural nodules (odds ratio, 3.83; 95% CI: 1.23, 11.89) withfunctional impairment. Presence and number of pleural plaquesdid not improve model accuracy for gas exchange impairment prediction(P > .05).

CONCLUSION: Thin-section CT grading of interstitial lung diseaseis useful in assessing the likelihood of pulmonary gas exchangeimpairment at rest (DLCO) and during exercise ( ${Delta}$ P[A-a]O₂/VO₂)in workers with long-term asbestos exposure.