Roles of the apparent diffusion coefficient and tumor volume in predicting tumor grade in patients with choroid plexus tumors

Purpose: To explore the utility of the apparent diffusion coefficient (ADC) and tumor volume to predict histological grade and prognosis in patients with choroid plexus tumors. Methods: ADC and tumor volumes were retrospectively evaluated in 25 patients with choroid plexus papilloma (CPP; WHO grade 1 [n = 13]), atypical CPP (aCPP; grade 2 [n = 8]), or choroid plexus carcinoma (grade 3 [n = 4]) The prognostic roles of ADC and tumor volume were assessed. Results: There were significant differences in mean and minimum ADC values, and tumor volume among the WHO grades (p = 0.033, p = 0.044, and p = 0.014, respectively). Receiver-operating characteristic analysis revealed a mean cutoff ADC value ≤ 1.397 × 10⁻³ mm²/s for aCPP (sensitivity = 0.667, specificity = 0.923). Multiple linear regression analysis demonstrated that both mean ADC (β = − 0.455, p = 0.005) and tumor volume (β = 0.513, p = 0.002) were correlated with WHO grade (adjusted R² = 0.520, p = 0.005). Kaplan-Meier curve analysis identified poorer survival in patients with WHO grade 2 and 3 tumors than in those with WHO grade 1 disease (p = 0.049 and p = 0.012, respectively). A mean ADC ≤ 1.397 × 10⁻³ mm²/s (p = 0.001) and tumor volume 21.05 ml (p = 0.031) predicted significantly poorer survival. Conclusion: Mean ADC and tumor volume were correlated with WHO grade of choroid plexus tumors. A lower ADC value and a larger tumor volume predicted a poorer prognosis.