Comparing film and digital radiographs for reliability of pneumoconiosis classifications: a modeling approach.

RATIONALE AND OBJECTIVES: The International Labour Office (ILO) system for classifying chest radiographic changes related to inhalation of pathogenic dusts is predicated on film-screen radiography. Digital radiography has replaced film in many centers. Digital images can be printed on film ("hard copy") or can be viewed at a computer workstation ("soft copy"). The goal of the present investigation was to compare the inter-reader and intra-reader agreement of ILO classifications for pneumoconiosis across image formats. MATERIALS AND METHODS: Traditional film radiographs, hard copy digital images, and soft copy digital images from 107 subjects were read by six B readers. A multiple reader version of the inter-reader kappa statistic was compared across image formats. Intra-reader kappa comparisons were carried out using an iterative least-squares approach (unadjusted analysis) as well as a two-stage regression model adjusting for readers and subject-level covariates. RESULTS: There were few significant differences in the inter-reader and intra-reader agreement across formats. For parenchymal abnormalities, inter-reader and intra-reader kappa values ranged from 0.536 to 0.646, and 0.65 to 0.77, respectively. In the covariate-adjusted analysis film-screen radiography was generally associated with a numerically greater reliability (ie, higher kappa values) than the other image formats, although differences were rarely statistically significant. CONCLUSION: Film-screen radiographs, hard copy digital images, and soft copy digital images yielded similar reliability measures. These findings provide further support to the recommendation that soft copy digital images can be used for the recognition and classification of dust-related parenchymal abnormalities using the ILO system.

Classification of voluntary cough sound and airflow patterns for detecting abnormal pulmonary function.

BACKGROUND: Involuntary cough is a classic symptom of many respiratory diseases. The act of coughing serves a variety of functions such as clearing the airways in response to respiratory irritants or aspiration of foreign materials. It has been pointed out that a cough results in substantial stresses on the body which makes voluntary cough a useful tool in physical diagnosis. METHODS: In the present study, fifty-two normal subjects and sixty subjects with either obstructive or restrictive lung disorders were asked to perform three individual voluntary coughs. The objective of the study was to evaluate if the airflow and sound characteristics of a voluntary cough could be used to distinguish between normal subjects and subjects with lung disease. This was done by extracting a variety of features from both the cough airflow and acoustic characteristics and then using a classifier that applied a reconstruction algorithm based on principal component analysis. RESULTS: Results showed that the proposed method for analyzing voluntary coughs was capable of achieving an overall classification performance of 94% and 97% for identifying abnormal lung physiology in female and male subjects, respectively. An ROC analysis showed that the sensitivity and specificity of the cough parameter analysis methods were equal at 98% and 98% respectively, for the same groups of subjects. CONCLUSION: A novel system for classifying coughs has been developed. This automated classification system is capable of accurately detecting abnormal lung function based on the combination of the airflow and acoustic properties of voluntary cough.

Comparison of digital radiographs with film radiographs for the classification of pneumoconiosis.

RATIONALE AND OBJECTIVES: Digital chest imaging has replaced film chest radiographs in many centers, but the International Labour Organization classification system, which is the most widely used system for recognition and classification of dust-related abnormalities, is predicated on film chest radiographs. The purpose of this study was to evaluate the equivalency of digital chest radiographs (including both hard copy and soft copy) with film radiographs for the recognition and quantification of abnormalities consistent with pneumoconiosis using the International Labour Organization classification system. MATERIALS AND METHODS: Digital chest images and film images, obtained from 107 subjects with a range of parenchymal and pleural abnormalities, were classified in random order by six B readers. RESULTS: Readings of film and soft copy images were equivalent for small opacity profusion; readings of hard copy images had significantly greater prevalence of small opacities compared to film and soft copy. The prevalence of large opacities differed significantly among all three image formats: hard copy greater than film greater than soft copy. However, film and soft copy readings for large opacities did not differ significantly when images demonstrating the coalescence of small opacities that had not yet become a large opacity were grouped with large opacities. The prevalence of pleural abnormalities differed significantly among all three image formats: film greater than hard copy greater than soft copy. CONCLUSIONS: Film and soft copy images can be recommended for the recognition and classification of dust-related parenchymal abnormalities using International Labour Organization classifications. The role of digital radiography in reading for pleural abnormalities requires additional investigation.