Hyperdense Cerebellum

Case A: Prominent heterogeneous cerebellar hyperdensity is noted on sagittal, coronal, and axial CT images. Additional occipital lobe hyperdensity is evident on the sagittal reconstruction, indicating that the pathology is not limited to the posterior fossa. A coronal FLAIR image demonstrates cerebellar folia edema and diffuse sulcal hyperintensity involving the posterior fossa and supratentorial sulci. Leptomeningeal enhancement is evident on postcontrast coronal and sagittal images. In conjunction, the patient’s history of liver transplantation (suggesting immunocompromise), fever, and leptomeningeal enhancement most prominently involving the posterior fossa point toward the correct diagnosis of meningitis with cerebellar involvement.

Case B: The cerebellum is markedly hyperdense when compared with the abnormally diffuse hypodense appearance of the supratentorial brain. Sulcal effacement also is present in the supratentorial compartment. The findings are consistent with a diffuse, cerebral anoxic insult resulting from respiratory arrest after the patient sustained a trauma. A parieto-occipital subgaleal hematoma is noted on sagittal and axial images, providing further evidence of trauma.

Case C: Masslike enlargement of a mildly heterogeneously hyperdense cerebellum is noted on sagittal, coronal, and axial CT images. In addition, masslike enlargement of a heterogeneously hypodense pons is noted on sagittal CT. Of note, the supratentorial compartment, including the sulci, is normal in appearance. MRI demonstrates heterogeneous T2 hyperintensity and patchy enhancement associated with masslike enlargement of the pons, cerebellar peduncles, and cerebellum consistent with neoplastic infiltration.