A Multiparameter Diagnostic Model Based on MRI Volumetric ADC Histogram and Clinical Variables Accurately Differentiate Thymic Epithelial Tumors From Mediastinal Lymphomas

Abstract Background The management and prognosis of each type of anterior mediastinal mass differ substantially. Radical thymectomy is regarded as the preferred surgical approach for resectable TETs, whereas chemotherapy is the recommended treatment for mediastinal lymphoma after confirming the histological diagnosis through needle biopsy, and surgical procedures should be avoided. Consequently, an accurate diagnosis of mediastinal lymphoma and TETs holds paramount importance in clinical treatment and prognosis for patients with thymic neoplasms. Methods Patients of TETs and mediastinal lymphomas with histopathological proof were included in the present study. The ADC histogram parameters were extracted from ADC maps. Clinical characteristics, radiological features and ADC histogram metrics (incluning ADCmin, ADCmax, and ADCmean; 5th, 10th, 25th, 50th, 75th, 90th and 95th percentiles of ADC; skewness and kurtosis) were evaluated between two groups. Multivariate analyses were performed to identify the significant variables, which were then incorporated into a comprehensive diagnostic model. Receiver operator characteristics (ROC) curve analysis was subsequently carried out to evaluate diagnostic performance. A nomogram was developed to differentiate TETs and mediastinal lymphomas. Results A total of 130 consecutive patients, with 93 TET patients and 37 mediastinal lymphoma patients, were enrolled. It was observed that patients with mediastinal lymphomas exhibited a significantly younger age (38.11 ± 13.51 years vs. 53.66 ± 12.99 years, P < 0.001) and a significantly higher serum lactate dehydrogenase (LDH) elevation rate (54.1% vs. 2.2%, P < 0.001) compared to those with TETs. Furthermore, the maximal diameter of lesions and skewness were significantly larger in patients with mediastinal lymphoma, whereas 25th -95th percentile of ADC, ADCmax and ADCmean were significantly smaller compared to patients with TETs (all P < 0.05). The comprehensive diagnostic model was established based on forward stepwise regression, including age, serum LDH level and skewness, with higher AUC than skewness alone (0.914, 95%CI: 0.850–0.977 vs. 0.785, 95%CI: 0.701–0.869, P < 0.01). The predictive C-index nomogram performance was 0.917 (95%CI: 0.915–0.918). Conclusion The comprehensive diagnostic model which takes into account both ADC histogram parameters and clinical characteristics showed a promising value in the differential diagnosis of TETs and mediastinal lymphomas.