Describe the current understanding of the anatomy and function of perivascular spaces and the glymphatic system. Review the clinical relevance of dilatory changes to the perivascular spaces. Review commonly encountered PVS on MRI. Discuss the most effective imaging techniques for investigating perivascular flow changes and dilatation, as well as current challenges.

Perivascular spaces (PVS), or Virchow-Robin spaces, surround penetrating blood vessels of the brain allowing the flow of interstitial fluid (ISF) and have a role in brain “glymphatics” analogous to systemic lymphatic drainage. Although universally seen at 7T, PVS are most commonly microscopic and often not resolved on ≤3 Tesla magnets. PVS classically demonstrate CSF signal characteristics on all sequences when seen. Previous studies have reported correlations between the degree of dilatation and the quantity of visible PVS in a wide variety of clinical conditions as...

Anatomy and Function: Perivascular spaces (PVS) in the brain are channel-like extensions of the extracerebral fluid space. Interposed between penetrating cerebral blood vessels and the surrounding parenchyma, these fluid-filled spaces are lined by the invaginating pial membrane and a barrier of astrocytic endfeet with tight junctions, the glia limitans. The walls of the PVS differ between anatomical regions; Type 2 ‘Cortical’ PVS through the cortical grey matter and subcortical white matter have a single leptomeningeal layer, whereas Type 1 PVS centred in the basal ganglia...

The anatomy and physiology of perivascular spaces and their functional role in the glymphatic drainage system is increasingly described and reported in the literature. There are physiological features of perivascular spaces that are not yet well understood due to methodological difficulties and imaging limitations of glymphatic drainage. Increasing awareness of PVS and the functional glymphatic waste drainage role can add valuable insight into the mechanisms of chronic neurological disorders. With emergence of higher field strength MRI and novel quantitative imaging methods to non-invasively image the...

J. Thompson: Nothing to disclose J. Gajera: Nothing to disclose D. Brazier: Nothing to disclose J. Drummond: Nothing to disclose

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