 There is an unchanged peripherally enhancing lesion measuring up to 25 millimeters centered within the left basal ganglia with suggestion of an eccentric target sign with surrounding edema and resultant mild mass effect upon the left lateral and third ventricles. There are areas of diffusion restriction within both the lesion and the adjacent corona radiata. There is a low relative cerebral blood volume within the lesion, but mildly increased perfusion in the adjacent corona radiata, near prominent perforating lenticulostriate vessels, which therefore likely represents luxury perfusion. There is an unchanged subcentimeter focus of T2 hyperintensity in the left caudate nucleus, which is compatible with a chronic lacunar infarct. There are multiple additional unchanged subcentimeter foci of supratentorial intrinsic T1 hyperintensity and susceptibility effect that correspond to calcifications. There is mild diffuse enhancement and thickening of the dura along the left cerebral convexity that likely represents residual reaction to prior subdural hemorrhage. However, there is no evidence of acute intracranial hemorrhage. There are multiple patchy areas of T2 hypertensity throughout the cerebral white matter predominantly in a subcortical distribution, which have gradually progressed. There is gradually progressive global volume loss. The major cerebral flow voids are intact. The skull, paranasal sinuses, and scalp soft tissues are unremarkable.
1. A peripherally-enhancing lesion centered in the left basal ganglia that measures up to 25 mm has features most suggestive of toxoplasmosis and less likely lymphoma, perhaps with associated acute ischemia in the adjacent corona radiata due to vasculitis from inflammation or compression intraparenchymal vessels. Further evaluation via Thallium 201 Chloride SPECT may be useful for further characterization, if clinically warranted.2. Gradually progressive global volume loss may represent AIDS dementia.3. Multiple progressive scattered patchy areas of T2 hypertensity in the cerebral white matter may represent sequela of HIV-associated opportunistic infections, such as progressive progressive multifocal leukoencephalopathy or vasculopathy, for instance.4. Multiple unchanged intra-axial and extra-axial calcified lesions likely represent sequela of prior opportunistic infection. 