PURPOSE: To evaluate whether, and to which extent, experienced radiologists are
able to visually correctly differentiate transient from persistent subsolid
nodules from a single CT examination alone and to determine CT morphological
features to make this differentiation.
MATERIALS AND METHODS: We selected 86 transient and 135 persistent subsolid
nodules from the National Lung Screening Trial (NLST) database. Four experienced
radiologists visually assessed a predefined list of morphological features and
gave a final judgment on a continuous scale (0-100). To assess observer
performance, area under the receiver operating characteristic (ROC) curve was
calculated. Statistical differences of morphological features between transient
and persistent lesions were calculated using Chi-square. Inter-observer agreement
of morphological features was evaluated by percentage agreement.
RESULTS: Forty-nine lesions were excluded by at least 2 observers, leaving 172
lesions for analysis. On average observers were able to differentiate transient
from persistent subsolid nodules >= 10 mm with an area under the curve of 0.75
(95% CI 0.67-0.82). Nodule type, lesion margin, presence of a well-defined
border, and pleural retraction showed significant differences between transient
and persistent lesions in two observers. Average pair-wise percentage agreement
for these features was 81%, 64%, 47% and 89% respectively. Agreement for other
morphological features varied from 53% to 95%.
CONCLUSION: The visual capacity of experienced radiologists to differentiate
persistent and transient subsolid nodules is moderate in subsolid nodules larger
than 10 mm. Performance of the visual assessment of CT morphology alone is not
sufficient to generally abandon a short-term follow-up for subsolid nodules.