Fig. 2.

T2-weigthed (a), apparent diffusion coefficient (ADC) map (b), and T1-weighted post-contrast MR images of a 6-year-old male with a newly diagnosed brain lesion in the posterior fossa. Based on MRI alone, a medulloblastoma was felt to be the most likely tumor type with ependymoma included in the differential. The MRS shows prominent Lac and lipids. Cr was below normal tissue levels whereas Cho, albeit elevated relative to Cr, was close to normal tissue levels. NAA was depleted, and mIns was above normal levels. Particularly, the unremarkable Cho levels are not typical for grade IV medulloblastoma. High mIns is also unusual for medulloblastoma. Combining the impression from MRI and MRS, an ependymoma was considered to be the most likely tumor type, which was subsequently confirmed. Lac lactate, Cho choline, Cr creatine, NAA N-acetylaspartate, mIns myo-inositol