Operator-dependent reproducibility of size measurements of small phantoms and lung nodules examined with low-dose thin-section computed tomography

OBJECTIVE: We sought to assess the reproducibility of size measurements of small lung nodules examined with low-dose thin-section computed tomography (LDTSCT). MATERIALS AND METHODS: Three radiologists measured volume with a semiautomatic tool and diameters manually of 20 (equivalent diameter range, 5.3-11 mm) phantom nodules and 37 (mean diameter range, 5-8.5 mm) lung nodules in subjects undergoing LDTSCT. RESULTS: In phantoms, the worst 95% limits of agreement (95% LA) for volume were -3.0% and 3.0% within operator and -3.1% and 2.8% between operators. The coefficient of repeatability (CR) for diameter ranged between 0.51 and 0.67 mm within operator and the 95% LA were from -0.71 to 0.71 mm between operators. In nodules, the worst intraoperator 95% LA for volume were -14.4% and 17.6% within operator and -13.1% and 14.2% between operators. The CR for diameter ranged between 0.48 and 0.73 mm within operator and the 95% LA were from -1.16 to 1.16 mm between operators. CONCLUSION: Operator-dependent variability of size measurements of small nodules examined with LDTSCT is not negligible and should be considered in lung cancer-screening studies.