Thin-Section CT Findings of Arc-Welders’ Pneumoconiosis Daehee Han, MD1 Jin Mo Goo, MD1 Jung-Gi Im, MD1 Kyung Soo Lee, MD2 Do Myung Paek, MD3 Seong Ho Park, MD1 Index words: Lungs, diseases Lungs, interstitial disease Computed tomography (CT) Pneumoconiosis Korean J Radiol 2000; 1 : 79-83 Received February 17, 2000; accepted after revision June 13, 2000. Department of 1Radiology and the Institute of Radiation Medicine, MRC, Seoul National University College of Medicine; Department of 2Radiology Samsung Medical Center, Sungkyunkwan Universty School of Medicine; 3School of Public Health, Seoul National University. Supported in part by a grant from Seoul National University Hospital (1996) Address reprint requests to: Jung-Gi Im, MD, Department of Diagnostic Radiology, Seoul National University Hospital, 28, Yongon-Dong, Chongno-Gu, Seoul 110-744, Korea. Telephone: (822) 760-2584 Fax: (822) 743-6385 e-mail: imjg@radcom.snu.ac.kr Korean J Radiol 1(2), June 2000 Objective: To describe the thin-section CT findings of arc-welders’ pneumoco- niosis. Materials and Methods: Eighty-five arc-welders with a three to 30 (mean, 15)- year history of exposure underwent thin-section CT scanning. The extent of abnormalities detected was correlated with the severity of dyspnea and pul- monary function tests. For comparison, images of 43 smoking males (mean 25 pack-year) who underwent thin-section CT for other reasons (smokers’ group) were also analyzed. Results: Fifty-four welders (63.5%) and six smokers (14.0%) showed positive findings. Predominant thin-section CT findings were poorly-defined centrilobular micronodules (30/54, 55.6%), branching linear structure (18/54, 33.3%), and ground-glass attenuation (6/54, 11.1%). In the smokers’ group, poorly-defined micronodules were found in four patients, branching linear structures in one, and ground-glass attenuation in one. In welders, the extent of abnormalities seen on thin-section CT showed no significant correlation with the severity of dyspnea or the results of pulmonary funotion test. Conclusion: Poorly-defined centrilobular micronodules and branching linear structures were the thin-section CT findings most frequently seen in patients with arc-welders’ pneumoconiosis. Less commonly, extensive ground-glass attenua- tion was also seen. A rc-welders pneumoconiosis is caused by chronic inhalation of inorganic dust fumes during the welding procedure. The principal component of the inhaled dust is iron-oxide; thus, the condition is also known as welders’ siderosis (1 4). After the first description in 1936 by Doig and McLaughlin (1), a num- ber of studies of the radiographic findings of the disease follewed (2, 3). The thin-sec- tion CT findings of 21 cases of arc-welders’ pneumoconiosis have been described by Akira et al. (4) in a collation of uncommon pneumoconiosis. The purpose of this study was to describe the thin-section CT findings of arc- welders’ lung. SUBJECTS AND METHODS Subjects Between April 1994 and January 1995, 85 arc-welders working in shipbuilding yards or assembly plants were referred to our hospital for thin-section CT scanning aimed at evaluating alleged lung abnormalities. Among them, 74 underwent CT be- cause of respiratory symptoms without overt abnormal chest radiographic findings, 79