Computed Tomography Hyperdense Lesions

Case A: A small focus of hyperdensity is present in the left middle cerebellar peduncle. The CT angiogram demonstrates a tangle of vessels just lateral to this focus of hemorrhage. A conventional catheter angiogram confirms the presence of an arteriovenous malformation with arterial supply from the left anterior inferior cerebellar artery and pontine perforators and early filling of the straight, transverse, and sigmoid sinuses. The lesion was subsequently treated with liquid embolic material (not shown).

Case B: A left occipital lesion demonstrates peripheral hyperdensity. There is surrounding edema with local mass effect and effacement of the left occipital horn. After administration of contrast, superimposed enhancement is seen along the peripheral portions of the mass. On the coronal reformats, an additional smaller hyperdense right cerebellar lesion with ring enhancement is noted. Given the patient’s history of lung cancer, these findings are consistent with lung metastases.

Case C: Small, discrete hyperdensities measuring 150 to 200 HU are consistent with calcifications in the left occipital lobe. Surrounding parietal occipital hypodensity and effacement of the left ventricular atrium are noted. CT angiogram maximum intensity projection image does not demonstrate abnormal associated vessels. Gadolinium-enhanced, T1-weighted MRI shows no associated enhancement. Marked T2/FLAIR hyperintense signal is noted correlating with the CT hypodensity. Gradient echo imaging shows calcific foci appearing as punctate foci of susceptibility. PET imaging demonstrates a predominantly hypometabolic lesion. Pathologic evaluation after surgical resection revealed an oligodendroglioma.

Case D: A CT scan of the brain demonstrates a mass lesion centered in the left anterior basal ganglia. There is an irregular hyperdense rim with a hypodense center. On MRI, the rim enhances and has restricted diffusion characterized by hypointensity on the ADC images. The findings are suggestive of a hypercellular lesion with internal necrotic or cystic components. The patient was given a diagnosis of lymphoma, and marked improvement of the enhancing lesion occurred after IV methotrexate was administered.