Spiral CT of pulmonary nodules: interobserver variation in assessment of lesion size

The aim of this study was to assess interobserver variability in size deter mination of pulmonary 'nodules at spiral CT: Twenty-three patients with kno wn pulmonary nodules (diameter 2-40 mm, mean diameter 7 mm) underwent spira l chest CT (collimation 5 mm, pitch 1). images were reconstructed at 3- and 5-mm intervals (RX), Hard copies were analyzed by two radiologists who rec orded every module with regard to location, diagnostic confidence ("definit e" "probable") and nodule size in increasments of 1mm with specific attenti on to correct clasification into one of three size classes (<5 mm, 6-10 mm > 10 mm). Interobserver viability was determined with Pearson's correlation coefficient and kappa measure. Of a total of 286 nodules, 103 nodules were found accordingly by both readers at 3 mm RI, and 96 at 5 mm RI. There was a good correlation of measurements (ia millimeters) between both readers ( Pearson's correlation coefficient 0.89-0.95). lnterobserver variability in categories was good at both reconstruction intervals (kappa: 0.61 at 3 mm, 0.74 at 5 mm RI) and very good (0.81) at 5 mm RI when uncertain nodules wer e excluded. Spiral CT allows reproducible size determination of pulmonary n odules as shown by good interobserver agreement in exact size measurement a nd categorize into three size classes.