ORIGINAL RESEARCH Apparent Diffusion Coefficients for Differentiation of Cerebellar Tumors in Children

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps provide information at MR imaging that may reflect cell attenuation and integrity. We hypothesized that cerebellar tumors in children can be differentiated by their ADC values. METHODS: Brain MR imaging studies that included ADC maps were retrospectively reviewed in 32 patients with histologically proved cerebellar neoplasm. There were 17 juvenile pilocytic astrocytomas (JPA), 8 medulloblastomas, 5 ependymomas, and 2 rhabdoid (atypical teratoid/rhabdoid tumor [AT/RT]) tumors. Absolute ADC values of contrast-enhancing solid tumor regions and ADC ratios (ADC of solid tumor to ADC of normal-appearing white matter) were compared with the histologic diagnosis. ADC values and ratios of JPAs, medulloblastomas, and ependymomas were compared by using a 2-tailed t test and one-way analysis of variance (ANOVA). RESULTS: ADC values were significantly higher in pilocytic astrocytomas (1.65 0.27) (mean SD) than in ependymomas (1.10 0.11) (P .0003) and medulloblastomas (0.66 0.15) (P .0001). Ependymomas demonstrated significantly higher ADC values than medulloblastomas (P .0005). The observed differences were statistically significant on ANOVA (P .001). ADC ratios were also significantly different among these 3 tumor types. AT/RT ADC values were similar to medulloblastoma