Perivascular spaces

Question 1

Characteristics of PVS

Answer 1

• Pial- lined (not arachnoid)
• Accompany vessels (Entering penetrating arteries or leaving brain draining veins)

Filled with interstitial fluid (not CSF)
Don’t connect with subarachnoid space

Facilitates fluid (CSF-ISF) exchange
ISF drainage via PVSs

Question 2

Are they visible through grey matter?

Answer 2

Not visible, not even on 7T

Question 3

Types of PVSs

Answer 3

Type I: basal ganglia along LSAs asymptomatic

Type II: WM along perforating medullary arteries usually asymptomatic

Type III: midbrain, along collicular arteries + other dentate etc. Only type often symptomatic

Type IV: New anterior temporal lobe, opercular

Question 4

DDx of Enhancing PVSs

Answer 4

Infection or granulomatous disease
Vasculitis
Neoplasm (intrav. lymphoma or GBM)
Fulminant demyelinating disease

Question 5

Imaging appearane of perivascular space

Answer 5

Round/ovoid/linear/tubular
Often in variably-sized clusters, asymmetry common
Follows CSF on all sequences (75% suppress completely on FLAIR)
25% hyperintense rim
NO enhancement

Question 6

Entities with pathologic PVS

Answer 6

Congenital: Mucopolysaccharidoses

As route of acquired pathologc processes:
Infections (pyogenic,meningitis, cryptococcosis,TB_
Vasculitis
Neurosarcoidosis
Noninfectious inflammation (CLIPPERS)
Neoplasms (Intravascular lymphoma, GBM)

Question 7

Where do we see Hurler Holes?

Answer 7

Mucopolysaccharidoses

T2 hyperintense, suppress on FLAIR

Question 8

Enhancing PVSs

Answer 8

Linear, dotted line or punctate enhancement

Meningitis, Vasculitis
Neurosarcoid, Intravascular lymphoma, GBM

CLIPPERS, Inflam Amyloid, Lymphomatoid granuloma, Fulminant demyelinating, Meningiomatosis, IgG4RD, LCH