Diffuse white matter changes are demonstrated throughout the left cerebral hemisphere with generalised mass effect resulting in effacement of the cortical sulci near the vertex. Multifocal areas of sub-centimeter nodular enhancement, which are confluent in some areas. No diffusion restriction within the areas of enhancement, however there is a punctate region of diffusion restriction in the left middle frontal gyrus, consistent with a recent infarct.
Flow diverter stent across the neck of left cavernous/ophthalmic ICA large aneurysm. Altered signal within the stent characteristic of susceptibility related signal loss. The aneurysm sac measures up to 1.4 cm, not significantly increased compared to pretreatment imaging. Subtle reduced calibre and signal intensity of distal arteries in the left cerebral hemisphere.
Ventricles and midline structures are otherwise satisfactory. No hydrocephalus.
Conclusion: Diffuse left cerebral hemisphere white matter changes and "non-ischaemic cerebral enhancing" (NICE) lesions are most compatible with foreign body reaction to microembolisation of the hydrophilic polymer (SHIELD) in this clinical context. Two small left frontal MCA cortical infarcts noted. Persistent filling of left ICA aneurysm.