The NIOSH B Reader Certification Program: Looking to the Future. Morgantown, WV: National Institute for Occupational Safety and Health, Publication No. 2009-140, 2009 Apr; :28-56
The purpose of screening is to identify diseases early in their course, before an individual would ordinarily seek medical care and when existing interventions may favorably affect disease outcome (1). Screening tests should be acceptable to those at risk for disease; have reasonable cost, effectively separate those with and without disease; and be sufficiently standardized to be performed with accuracy, consistency, and reproducibility. For pneumoconiosis screening, chest radiographs are acceptable, widely available and relatively inexpensive. However, the insensitivity of chest films for detection of early or moderate pneumoconioses limits their efficacy in screening. The ILO classification system, developed initially for epidemiologic purposes, is limited for purposes of clinical screening and diagnosis by high intra- and interobserver variability. Further, chest radiography is widely recognized as an ineffective tool for detection of airways abnormalities such as emphysema from dust exposure. Within the past 20 years, newer imaging techniques such as conventional and high-resolution computerized tomography (HRCT) have enhanced visualization of the lung. Kreel and Raithel were pioneers in the use of CT to evaluate asbestosis and silicosis, with several papers from the 1970s documenting the enhanced ability of CT to show pleural plaques, subpleural parenchymal abnormalities, parenchymal bands, and micronodules in exposed workers with normal chest radiographs (2, 3). A further advance in the mid-1980's was the use of thin section, high resolution CT (thin collimation slices performed with a small field of view and reconstructed with a high spatial frequency algorithm) with both supine and prone images to more precisely characterize the extent and type of parenchymal disease (4-6). These techniques have improved the detection of early pathological changes and increased sensitivity and specificity in detecting occupational pleural and parenchymal abnormalities. There is an increasing body of literature aimed at standardizing interpretation and validating the usefulness of HRCT in screening and surveillance for pneumoconioses. Our purpose in this working paper is to review the published literature on the role of CT in pneumoconiosis screening, assess the current state-of-the-art regarding standardized technique and scoring of CTs, comment on directions in the use of high-resolution lung imaging, and outline future research needs.