Predictive Value of One-Dimensional Mean Computed Tomography Value of Ground-Glass Opacity on -High-Resolution Images for the Possibility of Future Change

Objectives: The purpose of this study was to evaluate the relationship between clinical and radiological findings and the progression of ground-glass opacity (GGO) and to identify risk factors that predict the outcome of pure GGO lesions. Methods: A retrospective study was conducted on 63 nodules of pure GGO. Clinical characteristics, the largest diameter, shape, and marginal characteristics, and one-dimensional mean computed tomography (m-CT) value of the GGO lesions were evaluated. During follow-up, 12 GGO lesions increased in size, and 17 appeared as solid portion. These 29 lesions were classified as growth group, and the remaining 34 lesions as stable group. Results: The m-CT values were -634.9 15.3 and -712.1 +/- 14.1 HU for the growth and stable groups, respectively. The growth group was strongly associated with high m-CT values (p = 0.0007) and a history of lung cancer (p = 0.0389), whereas association with smoking habits and the shape of the GGO nodules was marginal. The m-CT values and a history of lung cancer were independent predictors for future changes in GGO lesions (p = 0.0023 and p = 0.0129, respectively). Sixteen of 18 lesions (88.9%) in patients without a history of lung cancer and with low m-CT values showed no nodule changes. Conclusions: The m-CT value of GGO lesions is a risk factor associated with their future change. The interval of follow-up CT scanning or treatment policy should be determined considering the m-CT value.