Observer variation in computed tomography of pleural lesions in subjects exposed to indoor asbestos

To assess the reliability of computed tomography (CT) in detecting discrete pleural lesions, the interobserver and intra-observer variability in readi ng the conventional and high-resolution CT (HRCT) scans of 100 volunteers, who had worked for greater than or equal to 10 yrs in a building with known asbestos contamination, was evaluated. In the first session, pleural abnormalities were detected by a single radio logist (A(1)) in 13 subjects. In the second session, the scans were read ag ain independently by the same radiologist (A(2)) and two other experienced radiologists (B, C). The final decision for the presence of pleural lesions was made in a final consensus reading. This gave a diagnosis of pleural abnormalities in 18 subjects, of whom eigh t (44%) had been detected by all three readers, five (28%) by two readers a nd four (22%) by only one reader; one scan, rated normal by all readers dur ing the second session, was reconsidered because pleural abnormalities had been noted at the first reading (A(1)). The intra-observer agreement for re ader A was good (kappa (kappa) 0.68) but the interobserver agreement betwee n the readers was only fair to moderate (weighted kappa: A(2)-B = 0.43, A(2 )-C = 0.45, B-C = 0.26) in the second reading session. In conclusion, when looking for the prevalence of pleural lesions in indoor asbestos exposed subjects, the potential lack of consistency in reporting the presence of small pleural abnormalities must be borne in mind and stric t precautions must be taken.