Fig 11.

Calcification in tumor. This 12-year-old girl had a 2-month history of intermittent headaches, emesis, and left hemiparesis. Her initial CT scan (not available) showed moderate hydrocephalus and a fourth-ventricular mass. Conventional MR imaging images (not shown) demonstrated a partly cystic and partly solid enhancing mass. A smaller nonenhancing heterogeneous component in the right dorsal pons is noted to have a round area of markedly hypointense signal intensity (arrow) on SWI (A) that corresponds to coarse calcification (arrow) on the postbiopsy CT (B). Dilation of the temporal horns (asterisks) due to obstructive hydrocephalus is also observed. Pathology revealed a diffusely infiltrating low-grade (I-II) astrocytoma with pilocytic features. The dark signal intensity on SWI was due to calcification in this low-grade glioma.