Apparent diffusion coefficient values in differentiating benign and malignant thoracic masses in children and young adults

Background: In children and young adults, tumors in the chest and thoracic wall exhibit a wide variety of types, making it challenging to differentiate between benign and malignant cases before invasive histopathological examination.

Purpose: To evaluate the utility of apparent diffusion coefficient (ADC) for discriminating malignant thoracic masses in children and young adults.

Material and methods: This retrospective study included chest magnetic resonance imaging (MRI) scans in patients aged <30 years. Patients' age and sex, tumor location (mediastinum or thoracic wall), tumor size, MR characteristics including necrosis or hemorrhage, and ADC values were assessed.

Results: Malignant masses were found in older patients (mean age = 18.0 ± 8.1 vs. 10.6, ± 9.1 years; P = 0.008), had lower mean ADC values (0.765 ± 0.298 vs. 2.051 ± 0.855 × 10^-3 mm²/s; P < 0.001), and showed more internal hemorrhage (6/12 vs. 17/86; P = 0.031) compared to benign masses. Univariate and multivariate regression analyses also showed significant differences in age, tumor size, and ADC values. In the diagnostic performance analysis, age (area under the receiver operating characteristic curve [AUC] = 0.723, 95% confidence interval [CI] = 0.624-0.809; P = 0.004) and ADC mean value (AUC = 0.941, 95% CI = 0.874-0.978, P < 0.001) were significant. The optimal cutoff values were 13 years for age (sensitivity = 83.3%, specificity = 61.6%) and an ADC mean of 1.196 × 10^-3 mm²/s (sensitivity = 100%, specificity = 86.1%) for discriminating malignant from benign thoracic masses.

Conclusion: When evaluating thoracic masses in children and young adults, older age and lower ADC values help identify malignancy.