Objective:To investigate the CT imaging features and the variation patterns of malignant solid pulmonary nodules（MSPNs）in different sizes.Methods:We studied 151 MSPNs of 150 patients with peripheral lung cancer confirmed by surgery and pathology between January 2016 and December 2019. According to their sizes，the nodules were divided into four groups：Group A（21 nodules，diameter ≤ 1.0 cm）；Group B（40 nodules，1.0 cm < diameter ≤ 1.5 cm）；Group C（48 nodules，1.5 cm < diameter ≤ 2.0 cm）；Group D（42 nodules，2.0 cm < diameter ≤ 3.0 cm）. We compared and analyzed the clinical and CT imaging features of the four groups.Results:Most MSPNs in the four groups were located in the upper lobes of the lung，not attached to the pleura and having irregular margins. As the MSPNs increased in diameter，the proportion of regular shapes（round or oval），homogeneous density，air bronchogram sign，lobulation sign，spiculation sign，vascular convergence sign，and pleural retraction sign in the nodules increased significantly（ P < 0.05）. Yet the proportion of calcification，bronchus encapsulated air sign，cavities，and halo sign did not vary significantly among the four groups（ P > 0.05）. Conclusions:The CT imaging features of the MSPNs varied as they grew and the variations followed certain patterns. The knowledge of the variation patterns helps early clinical diagnosis of malignant nodules.

Objective:To investigate the CT imaging features and the variation patterns of malignant solid pulmonary nodules（MSPNs）in different sizes.Methods:We studied 151 MSPNs of 150 patients with peripheral lung cancer confirmed by surgery and pathology between January 2016 and December 2019. According to their sizes，the nodules were divided into four groups：Group A（21 nodules，diameter ≤ 1.0 cm）；Group B（40 nodules，1.0 cm < diameter ≤ 1.5 cm）；Group C（48 nodules，1.5 cm < diameter ≤ 2.0 cm）；Group D（42 nodules，2.0 cm < diameter ≤ 3.0 cm）. We compared and analyzed the clinical and CT imaging features of the four groups.Results:Most MSPNs in the four groups were located in the upper lobes of the lung，not attached to the pleura and having irregular margins. As the MSPNs increased in diameter，the proportion of regular shapes（round or oval），homogeneous density，air bronchogram sign，lobulation sign，spiculation sign，vascular convergence sign，and pleural retraction sign in the nodules increased significantly（ P < 0.05）. Yet the proportion of calcification，bronchus encapsulated air sign，cavities，and halo sign did not vary significantly among the four groups（ P > 0.05）. Conclusions:The CT imaging features of the MSPNs varied as they grew and the variations followed certain patterns. The knowledge of the variation patterns helps early clinical diagnosis of malignant nodules.