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G. De Jonge
MA01 - Improvement and Implementation of Lung Cancer Screening (ID 368)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Radiology/Staging/Screening
- Presentations: 1
MA01.07 - Influence of Nodule Morphology on Inter-Reader Variability of Volume and Diameter Measurements in CT Lung Cancer Screening (ID 4750)
11:00 - 12:30 | Author(s): G. De Jonge
The high number of false positive screen results is a major disadvantage of lung cancer screening by low-dose chest computed tomography (CT). Measurement strategy influences the false-positive rate, and nodule morphology may influence measurement of nodule size. Comparison between inter-reader variation for semi-automatic volume measurements and manual diameter measurements are scarce. Therefore, we aimed to evaluate the influence of nodule morphology on inter-reader variability and assessment of growth for semi-automatic volume measurements and manual diameter measurements, in intermediate-sized solid nodules found in CT lung cancer screening.
Twenty-five nodules of each morphological category: smooth, lobulated, spiculated and irregular, were randomly selected from 93 participants of the Dutch-Belgian randomized lung cancer screening trial (NELSON). Semi-automatic volume measurements were performed using Syngo LungCARE[®] software. Two chest radiologists independently measured maximum and mean diameters manually. The impact of nodule morphology on inter-reader variability was evaluated based on the systematic error and 95% limits of agreement (LoA). Inter-reader variability was compared to volume change cutoff at 3-month follow-up based on NELSON for nodule growth and Lung-RADS diameter cutoff.
For manual diameter measurements, a significant systematic deviation was found between readers in smooth, lobulated, and spiculated nodules. The deviation was up to 1.5 mm based on maximum diameter measurements, and 1.2 mm based on mean diameter measurements. For semi-automatic volume measurements, no statistically significant systematic deviation was found. For lobulated, spiculated, and irregular nodules, the 95%-LoA for mean diameter measurements was up to 66% larger than the 1.5 mm cutoff for nodule growth. For volume measurements, the 95%-LoA exceeded the 25% growth cutoff for spiculated and irregular nodules, but only by up to 12%.
Nodule morphology has a greater effect on size assessment based on manual diameter measurements than based on volume measurements. The larger inter-reader variability for manual diameter measurement may cause misclassification of spiculated nodules when assessing growth in 24% of cases. Therefore, semi-automatic volume measurement is recommended for nodule size and growth determination in CT lung cancer screening.
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