Giant Tumefactive Perivascular Spaces MRI

Clinical Details: headache.

FLAIR

T1W

T2W

T2*GRE

T1 PC

MRI brain with Contrast

MRI study of brain with contrast shows a well defined, multilocular cystic lesion isointense to CSF, non-enhancing on post contrast involving left thalamus, adjacent mesencephalic mid brain. An associated mild mass effect causing third ventricle compression however no obvious obstructive hydrocephalus. No obvious low signal intensity haemosiderin staining on GRE. No obvious adjacent perilesional oedema on FLAIR.

Imaging findings suggestive of giant Tumefactive Peri vascular space – a benign non-tumoural cyst.
Suggested follow-up imaging for mass effect.

Giant Tumefactive Perivascular Spaces

Perivascular spaces (PVSs) are pial-lined, interstitial fluid-filled structures that accompany penetrating arteries, also known as Virchow-Robin spaces when enlarged, they may cause mass effect and can be mistaken for various ominous pathologic processes.
Often appear as clusters of variably sized cysts that are isointense to CSF on all pulse sequences and do not enhance, Gaint Tumefactive VR spaces assuming bizarre configurations with striking mass effect should not be mistaken for neoplasm.
They are most common in the mesencephalo thalamic region and may cause hydrocephalus.

Reference: Giant Tumefactive Perivascular Spaces Karen L. Salzman, Anne G. Osborn, Paul House, J. Randy Jinkins, Adam Ditchfield, James A. Cooper and Roy O. Weller
American Journal of Neuroradiology February 2005, 26 (2) 298-305

Enlarged perivascular spaces

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Enlarged peri vascular spaces also called Virchow Robin (VR) spaces.
These are Pial lined interstitial fluid filled structures that accompany penetrating arteries, do not communicate with subarachnoid space.
Noted as an incidental finding and are of no clinical significance.

Typical and commonest location is basal ganglia, often bilateral.
Other common locations are sub insular cortex along external capsule, lobar white matter, thalami, mid brain.

Size is usually 5mm or less. Occasionally expand and attain large size up to several cms.

Usually found in clustures.
Iso intense to Csf on all pulse sequences.
Closest differential particularly on CT is a chronic lacunar infarct due to small vessel occlusion or a chronic lacune secondary to micro bleed ( in Peri vascular space surrounding brain parenchyma lacks Gliosis which is seen in case of chronic lacune or lacunar infarct as a thin rim of Gliosis on MRI FLAIR)

Enlarged Perivascular (Virchow Robin) Spaces

MRI Brain, Axial T2, FLAIR, Diffusion; CT Brain

Findings:
Multiple T2 hyperintense foci cluttered in right parietal white matter and a single in right frontal lobe white matter, complete signal suppression on FLAIR are the enlarged peri vascular spaces.
Hypodense on CT.
Adjacent brain show normal signals. No any evidence of Gliosis.

On CT, the closest differential is lacunar infarcts which can be ruled out by demonstrating absence of surrounding rim of Gliosis on MRI FLAIR.

Enlarged peri vascular spaces also called Virchow Robin spaces.
Typical and commonest location is basal ganglia.
Usually found in clustures.
Iso intense to Csf on all pulse sequences.
May be seen in lobar white matter and even in brain stem.