Figure 2. CT and MRI images showing blood–fluid levels in cases of primary intracranial malignancies and metastases to the brain. (a) A post-contrast axial T₁ weighted image through the posterior fossa of an 18-year-old woman reveals a cystic lesion with a small mural nodule displacing the fourth ventricle. A smaller unencapsulated cyst in the right cerebellum shows enhancement of the dependent component creating an uneven interface within the lesion. At histopathology the lesion was found to be a haemangioblastoma which was part of a larger spectrum of findings in a case of Von Hippel–Lindau syndrome. (b,c) CT following resection of the midline tumour reveals a persistence of the smaller right cerebellar cyst. Enhancement of the dependent isodense solid component of the lesion by contrast creates an interface, which simulates leakage of contrast into a cyst thereby exemplifying a spurious fluid level within an intracranial lesion.