A 19-year-old man presented with diplopia and left-sided weakness, and a right thalamic abscess. (a) Axial T1 postcontrast. A ring enhancing mass is present in the right thalamus (arrow). (b) DWI sequence. Signal hyperintensity is present in the lesion (arrow). (c) ADC map. Signal hypointensity in the lesion (arrow) confirms decreased diffusion. In the appropriate clinical context, this constellation of findings is consistent with a pyogenic abscess.