A<unk>  is an abnormal radiologic sign on MRI or CT scans obtained using radiocontrast. On the image, there is an area of decreased density (see radiodensity) surrounded by a bright rim from concentration of the<unk>  contrast dye. This enhancement may represent breakdown of the blood-brain barrier and the development of an inflammatory capsule. This can be a finding in numerous disease states. In the brain, it can occur with an early brain abscess as well as in Nocardia infections associated with lung cavitary<unk> s. In patients with HIV, the major differential is between CNS lymphoma and CNS toxoplasmosis, with CT imaging being the appropriate next step to differentiate between the two conditions.
Ring-enhancing lesion
Palisaded encapsulated neuroma
Hippocampal sclerosis
Neurofibrillary tangle
Homogeneously staining region
Hippocratic facies
Conduplicato corpore
Geographic atrophy