Comparison of Conventional, Diffusion, and Perfusion MRI Between Low-Grade and Anaplastic Extraventricular Ependymoma.

The purpose of this study was to investigate and compare conventional MRI, DWI, and dynamic susceptibility contrast-enhanced perfusion-weighted imaging (DSC-PWI) characteristics between low-grade and anaplastic extraventricular ependymomas. Twenty-six patients with extraventricular ependymomas (19 anaplastic and seven low-grade) who underwent preoperative MRI were enrolled in this retrospective study. Conventional MRI and DWI were performed in all patients; DSCPWI was performed in 15 patients (11 with anaplastic ependymoma and four with low-grade ependymoma). Demographics, conventional MRI features, minimum relative apparent diffusion coefficient (rADC), and maximum relative cerebral blood volume (rCBV) of the low-grade and anaplastic ependymomas were compared. Diagnostic performance with optimal cutoff values was determined. Anaplastic extraventricular ependymomas were more likely to be located in the superficial supratentorial cerebral hemisphere ( = 0.026) and to present with pial and cortical involvement ( = 0.028 and 0.013, respectively) and necrotic degeneration ( = 0.014). The mean rADC ± SD of anaplastic ependymoma was significantly lower than that of low-grade ependymoma (0.8 ± 0.2 vs 1.2 ± 0.3, = 0.002). The mean rCBV of anaplastic ependymoma was significantly higher than that of low-grade ependymoma (15.7 ± 5.3 vs 9.0 ± 4.4, = 0.042). The cutoff values in grading extraventricular ependymoma were 1.02 for rADC and 10.43 for rCBV. Combining conventional MRI, DWI, and DSC-PWI allowed the best differentiation of low-grade and anaplastic ependymoma (AUC = 1.00). Conventional MRI, DWI, and DSC-PWI techniques may aid in assessing and grading extraventricular ependymomas.