Prognostic and predictive values of diffusion and perfusion MRI in paediatric intracranial ependymomas in a large national study

Objective: To assess the relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) derived, respectively, from perfusion and diffusion pre-operative MRI of intracranial ependymomas and their predictive and prognostic values. Methods: Pre-operative MRI and clinical data for intracranial ependymomas diagnosed between January 2000 and December 2013 were retrospectively retrieved from a web-based national database. MRI data included diffusion (62 patients) and perfusion (20 patients) MRI. Patient age, histopathological diagnosis, tumour location, ADC, relative ADC (rADC) and rCBV were considered as potential factors in a survival analysis. Survival rates were estimated using the Kaplan-Meier method. Univariate analyses were performed using the log-rank test to compare groups.We also performed a multivariate analysis, applying the Cox proportional hazards model. Results: ADC and rADC values within hypointense regions differed significantly between grades II and III (p50.01). The 75th percentile of ADC within hypointense regions and the 25th percentile of rCBV within nonenhancing lesions were prognostic of disease-free survival (p50.004, p50.05). A significant correlation was found between the 75th percentile of rCBV and the 25th percentile of rADC (p50.01) in enhancing regions of grade-III tumours. Conclusion: Pre-operative rADC and rCBV could be used as prognostic factors for clinical outcome and to predict histological grade in paediatric ependymomas.