Abstract
Objective
The purpose of this study was to determine how well radiologists could visually detect a change in lung nodule size on the basis of visual image perception alone.
Subjects and methods
Under IRB approval, 109 standard chest CT image series were anonymized and exported from PACS. Nine hundred forty virtual lung nodule pairs (six baseline diameters, six relative volume differences, two nodule types—solid and ground glass—and 14 repeats) were digitally inserted into the chest CT image series (same location, different sizes between the pair). These digitally altered CT image pairs were shown to nine radiologists who were tasked to visually determine which image contained the larger nodule using a two-alternative forced-choice perception experimental design. These data were statistically analyzed using a generalized linear mixed effects model to determine how accurately the radiologists were able to correctly identify the larger nodule.
Results
Nominal baseline nodule diameter, relative volume difference, and nodule type were found to be statistically significant factors (p < 0.001) in influencing the radiologists’ accuracy. For solid (ground-glass) nodules, the baseline diameter needed to be at least 6.3 mm (13.2 mm) to be able to visually detect a 25% change in volume with 95 ± 1.4% accuracy. Accuracy was lowest for the nodules with the smallest baseline diameters and smallest relative volume differences. Additionally, accuracy was lower for ground-glass nodules compared to solid nodules.
Conclusions
Factors that impacted visual size assessment were baseline nodule diameter, relative volume difference, and solid versus non-solid nodule type, with larger and more solid lesions offering a more precise assessment of change.
Key Points
• For solid nodules, radiologists could visually detect a 25% change in volume with 95% accuracy for nodules having greater than 6.3-mm baseline diameter.
• For ground-glass nodules, radiologists could visually detect a 25% change in volume with 95% accuracy for nodules having greater than 13.2-mm baseline diameter.
• Accuracy in detecting a change in nodule size began to stabilize around 90–100% for nodules with larger baseline diameters (> 8 mm for solid nodules, > 12 mm for ground-glass nodules) and larger relative volume differences (>15% for solid nodules, > 25% for ground-glass nodules).
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Abbreviations
- 2AFC:
-
Two-alternative forced-choice
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This study did not have funding.
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The scientific guarantor of this publication is Ehsan Samei.
Conflict of interest
The authors of this manuscript declare relationships with the following companies:
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Justin Solomon has relationships with the following entities, unrelated to the present publication: 12 Sigma, Sun Nuclear, Metis Health Analytics.
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Ehsan Samei has relationships with the following entities unrelated to the present publication: GE, Siemens, Bracco, Imalogix, 12 Sigma, Sun Nuclear, Metis Health Analytics, Cambridge University Press, and Wiley and Sons.
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Justin Solomon and Ehsan Samei have statistical expertise and provided the analysis.
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Written informed consent was waived by the Institutional Review Board because this was a retrospective study on anonymized image data.
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Institutional Review Board approval was obtained.
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Lukas Ebner is a co-first author.
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Solomon, J., Ebner, L., Christe, A. et al. Minimum perceivable size difference: how well can radiologists visually detect a change in lung nodule size from CT images?. Eur Radiol 31, 1947–1955 (2021). https://doi.org/10.1007/s00330-020-07326-2
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DOI: https://doi.org/10.1007/s00330-020-07326-2