[Differentiation of Solitary Pulmonary Nodules from Benign to Malignant Using Non-contrast Dual Energy CT Electron Density Values].

Purpose: The development of dual energy CT (DECT) has made it possible to provide not only morphological characteristics but also a wide range of quantitative information. The purpose of this study is to differentiate between benign and malignant solitary pulmonary nodules (SPN) by using electron density values obtained from DECT.

Methods: From the image data diagnosed as SPN, DECT images of 54 cases were selected, and the maximum electron density values of SPN were obtained. Electron density values were compared between benign and malignant cases by t-test. Comparisons between histopathological types and histological subtypes were performed by ANOVA. Logistic regression analysis was also applied to estimate the partial regression coefficients on electron density values.

Results: Electron density values were 3.56×10²⁰/mm³ for malignant and 3.51×10²⁰/mm³ for benign, with malignancy being significantly higher (p<0.001). ROC analysis showed that the AUC was 0.77. In a comparison between histopathologic types, electron density values were significantly higher for adenocarcinoma and squamous cell carcinoma (p<0.05). There were no significant differences among subtypes. Logistic regression analysis showed a regression coefficient of 1.24 (p<0.01).

Conclusion: Electron density values obtained from dual energy CT may serve as a useful quantitative parameter for differentiating between benign and malignant SPN. However, attention should be paid to certain histological subtypes, such as invasive mucinous adenocarcinoma, which may exhibit exceptionally low values.