 Redemonstrated is a T2 hyperintense lesion within the cerebellar vermis with regions of intrinsic T1 shortening and several foci of susceptibility artifact corresponding to previously noted calcifications as well as patchy regions of enhancement, not significantly changed from prior exams. Mild mass effect on the posterior wall the fourth ventricle is again noted without associated hydrocephalus. The mass measures 2.9 x 1.9 cm (previously 2.9 x 1.9 cm), not significantly changed compared with multiple prior exams (image 154, series 14). Low-lying cerebellar tonsils extending 6-7mm below the foramen magnum without peg-like appearance. There is moderate crowding. No evidence of acute ischemia or midline shift. No additional suspicious enhancement is identified. Normal flow voids are identified in the major intracranial vessels. Right maxillary sinus retention cyst and mild mucosal thickening.
1. Unchanged midline cerebellar vermian lesion with foci of calcification and enhancement with unchanged differential.2. Low lying but rounded cerebellar tonsils, equivocal for Chiari I malformation and possibly acquired secondary to the cerebellar vermis lesion - correlate with symptoms.