T2 hyperintense lesions of left caudate nucleus, left putaminal and right dentate nucleus , with perilesional edema.

Small corticomedullary T2 hyperintense lesions with faint enhancement.

Caudate and putaminal lesions demonstrates faint peripheric contrast enhancement whereas cerebeller lesion has strong peripheric and central nodular enhancement.

Caudate and cerebellar lesion have tiny microhemorrhages on SWI, a clue for diagnosis.

Toxoplasmosis

· Most common opportunistic CNS infection and most common cause of a mass lesion in AIDS
· Basal ganglia, thalamus, corticomedullary junction and cerebellum frequently involved
· Microhemorrhages can be seen on SWI, lesions may have ring or nodular enhancement
· Major ddx is lymphoma:
– Lymphoma is usually solitary whereas solitary lesions are uncommon in toxoplasmosis.
– Microhemorrhages are uncommon in lymphoma

Right temporal lobe

Effacement of the temporal horn of the right lateral ventricle and subtle hypodensity within the right temporal lobe

CT with contrast and MRI

Multiple sclerosis

Multiple white matter lesions involving the corpus callosum, peri-trigone region, subcortical, and deep white matter.
Ddx: other demyelination, vasculitis, small vessel disease, tosic/metabolic, watershed infarcts.