CT quantitative parameters in differential diagnosis of anterior mediastinal cysts and thymomas of types B1 and B2 less than 30 mm

To explore the value of CT quantitative parameters in differentiating anterior mediastinal cysts (AMCs) from type B1 and B2 thymomas. A total of 116 patients were retrospectively included in this study, comprising 86 patients with pathologically confirmed AMCs (all of which had been preoperatively misdiagnosed as thymomas and underwent surgical resection) and 30 patients with pathologically confirmed type B1 and B2 thymomas; all lesions measured less than 30 mm in maximum diameter. Three radiologists with 3, 9, and 25 years of experience independently analyzed imaging features. The long diameter, short diameter, mean, maximum, minimum, and standard deviations (SD) of CT values for the target nodule and the same-plane subscapularis muscle and other quantitative parameters were subsequently collected and other parameters were calculated. Univariate and multivariate logistic regression analysis were performed to confirm independent variables for differentiating AMCs from type B1 and B2 thymomas. Receiver operating characteristic (ROC) curves were plotted to evaluate the diagnostic performance of each parameter, and a consistency test among the radiologists was performed. On univariate analysis, AMCs demonstrated significantly lower short diameter, and lower mean, maximum, and minimum CT values on both unenhanced and enhanced scans compared with type B1 and B2 thymomas, as measured by each of the three radiologists (all p < 0.05). On multivariate analysis, short diameter, maximum CT value, and Relative Heterogeneous Rate of the Nodule (RHRN) on enhanced CT were identified as independent predictors for differentiating AMCs from type B1 and B2 thymomas. Among all quantitative parameters, the maximum enhanced CT value yielded the highest diagnostic performance, with a pooled area under the curve (AUC) of 0.911; the inter-observer intraclass correlation coefficient (ICC) for this parameter was 0.980 (95% CI: 0.973–0.986). Quantitative CT parameters derived from preoperative enhanced CT scans are valuable for differentiating type B1 and B2 thymomas from anterior mediastinal cysts and demonstrate high consistency among radiologists of varying experience levels. This study demonstrates that quantitative CT parameters significantly improve the differentiation between anterior mediastinal cysts and type B1 and B2 thymomas, enhancing diagnostic accuracy and reducing unnecessary surgical resection of patients with anterior mediastinal cysts, thereby advancing clinical radiology practice.