Interobserver and Intraobserver Variability in the Assessment of Pulmonary Nodule Size on CT Using Film and Computer Display Methods1

Considerable interobserver and intraobserver variability in measuring nodules exists using hard-copy and computer tools. Since a small change in diameter indicates a much larger change in volume, this may be significant when using early repeat CT to follow small pulmonary nodules. Computer-aided diagnostic tools that reproducibly measure nodule volume are strongly needed.