Image 1 & 2: Axial T2 weighted images of brain show a well-defined hyperintense
area behind the cerebellum. The lesion is of similar signal intensity to CSF.
Image 3: Axial T1 weighted image shows a low signal lesion causing mild
mass effect on the adjacent cerebellum.
Image 4: Coronal T1 weighted image shows that the lesion is located
underneath the tentorium on Lt side of the posterior fossa.
Image 5: Sagittal post gadolinium T1 weighted image reveals no enhancement
of the lesion. The apparent peripheral enhancement at its upper margin
represents enhancing blood within the displaced straight sinus. (T. Lai)
Key words: mri tumor neoplasm
Arachnoid cyst of the posterior fossa