Presentation
Incidental finding on routine brain MRI requested for the investigation of chronic headaches.
Patient Data
A well-defined rounded cystic lesion is seen involving the subcortical white matter of the right temporal pole. It follows fluid signal intensity on all sequences with CSF-like high T2 signal and complete central suppression on FLAIR. It is surrounded by moderate perilesional increased T2 signal. No overlying cortical involvement. On high-resolution T2 weighted images, additional smaller cystic/tubular fluid-filled lesions of similar MR appearances are present, likely representing dilated perivascular spaces.
No perilesional or intralesional enhancement is seen after contrast administration and no signal loss on SWI to suggest calcification or hemorrhage.
Anterior to the lesion a prominent loop of the right middle cerebral artery (best seen on axial high-resolution T2, coronal T2 and sagittal post-contrast T1) indents the adjacent cortex.
Case Discussion
Dilated perivascular spaces in the anterior temporal lobe are variants of tumefactive perivascular spaces and tend to involve the subcortical white matter.
The majority of these lesions are surrounded by perilesional changes in signal intensity. It is suggested that this finding represents gliosis secondary to mass effect with surrounding chronic ischemic changes.
Generally, dilated perivascular spaces tend to prefer certain specific locations. This characteristic is helpful in ruling out other sinister lesions. Another important distinguishing feature of anterior temporal lobe dilated perivascular spaces is its close proximity to the adjacent middle cerebral artery.
The lack of enhancement and size stability over time are also considered supportive features of dilated perivascular spaces.