High resolution CT in differentiating minimally invasive component in early lung adenocarcinoma

Objectives: To analyze high-resolution computed tomography (HRCT) appearances of early lung adenocarcinoma and evaluate HRCT in the differentiation of minimally invasive component in early lung adenocarcinoma. Materials and methods: HRCT appearances of 140 nodules (less than 2 cm in diameter) of early lung adenocarcinoma were reviewed retrospectively. All these nodules were proven by surgery and pathology including 60 nodules of minimally invasive adenocarcinoma (MIA) and 80 nodules of preinvasive lesion (PL). HRCT features of two groups of lung nodules, including shape, margin, pattern, diameter, diameter of solid component, vascular changes, air bronchogram, vacuole, pleural indentation and multiplicity were analyzed and compared using univariate logistic regression analysis. Attenuation values of pure ground-glass nodule, pure ground-glass component and solid component of mixed ground-glass nodule were compared by using unpaired t-test or Wilcoxon rank-sum test. Results: The statistically significant differences were found in shape, margin, pattern, diameter, diameter of solid component, pulmonary vein changes, air bronchogram and pleural indentation (Odds ratio [OR] = 3.115 [P = 0.001], OR = 3.754 [P = 0.011], OR = 9.815 [P = 0.000], OR = 1.306 [P = 0.000], OR = 1.361 [P = 0.031], OR = 6.971 [P = 0.000], OR = 6.167 [P = 0.000], OR = 2.296 [P = 0.027], respectively). The statistically significant difference was also found in attenuation value of solid component (t = 3.702, P = 0.000). By multivariate logistic analysis, attenuation value of solid component was significantly associated with MIA (OR = 1.005, P = 0.032). MIA was more often a larger, lobulated or irregular, mixed ground-glass nodule with a solid component larger than 5 mm, and higher attenuation values. In addition, MIA often had an abnormality in pulmonary vein, air bronchogram and pleural indentation. Conclusions: HRCT can demonstrate the morphological features of early lung adenocarcinoma and identify minimally invasive component. (C) 2014 Elsevier Ireland Ltd. All rights reserved.