Figure 3.

Twelve-month-old girl with medulloblastoma. This case represents the single MR imaging study in which neither neuroradiologist provided the correct diagnosis but in which ADC_min values by both readers indicated a correct diagnosis. A) Axial FLAIR image shows a heterogeneous mass in the fourth ventricle with hyperintense foci and a small fluid-fluid level suggestive of hemorrhage. B) Axial contrast-enhanced T1-weighted image shows small foci of contrast enhancement within a portion of the mass. C) Axial DWI image shows a hyperintense signal within the right half of the lesion, suggestive of low ADC values. D) Axial ADC map at the same level as C shows the lesion has regions of dark signal consistent with restricted diffusion in the right half of the mass. Mean ADC_min value measured by one observer was 0.569 mm²/s and that by the other observer was 0.631 mm²/s, suggesting the diagnosis of medulloblastoma.