CT Findings of Solitary Pulmonary Nodules Less than 8 mm to Differentiate the Malignant and Benign

We assessed CT features of the solitary pulmonary nodules (SPNs) smaller than 8 mm to evaluate the differences between the benign and malignant nodules. The study included 113 patients (66 male, 47 female, age range: 33-79 years) with SPNs smaller than 8 mm. Mean diameter of SPN on CT was 4.95 ± 1.19 cm; benign, 4.91 ± 1.24 mm; and malignant, 6.09 ± 1.01 mm. Of the 113 nodules, there were 23 (20.4%) malignant nodules and 90 (79.6%) benign nodules. The CT findings (size, shape, margin, density) of SPNs were analyzed. The statistical differences of the malignant and benign nodules were analyzed by x2 test. The differences of the benign and malignant nodules were in the margin and density. In the margins, spiculation and lobulation occurred with a significantly higher frequency in the malignant nodules (spiculated: 10/23, lobulated: 7/23) than the benign nodules (spiculated: 20/90, lobulated: 0/90) (p < 0.001). In the mixed or pure ground glass attenuation (14/23), the malignancy rates were significantly higher than the solid nodules (p < 0.001). In the mixed and pure attenuation, a lobulated or spiculated margin (12/14) was associated with a higher risk of malignancy (p = 0.005). In smaller than 8 mm nodules, the predictive CT findings of malignancy were spiculated or lobulated margin and mixed or pure attenuation.