Magnetic Resonance Imaging Evaluation of Perivascular Space Abnormalities in Neuromyelitis Optica

Ann Neurol. 2022 Aug;92(2):173-183. doi: 10.1002/ana.26419. Epub 2022 Jun 11.


Objective: Astrocytes outline the perivascular space (PVS) and regulate fluid exchange through the aquaporin-4 water channel. As neuromyelitis optica is an autoimmune astrocytopathy targeting aquaporin-4, we hypothesized that it could be associatied with PVS abnormalities.

Methods: A total of 34 patients, and 46 age- and sex-matched healthy controls from two independent cohorts (exploratory and validation dataset) underwent a standardized 3.0-T magnetic resonance imaging protocol including conventional and diffusion tensor imaging. Susceptibility-weighted imaging was also acquired in the exploratory dataset. We evaluated macroscopic and microstructural abnormalities of PVS in terms of enlargement and water diffusivity (DTI-ALPS index). In the exploration dataset, a susceptibility-weighted sequence was used to draw the regions of interest for the DTI-ALPS index calculation in areas having veins perpendicular to lateral ventricles. Between-group comparisons, correlations, and regression models were run to assess associations between PVS abnormalities, and clinical and magnetic resonance imaging variables.

Results: Patients had a higher frequency of severe PVS enlargement in the centrum semiovale (29.4% vs 8.7%), which correlated with brain atrophy, deep grey matter atrophy, and poorer cognitive performance (r-values range: -0.44, -0.36; p values: 0.01-0.046). In both datasets, patients had reduced DTI-ALPS index compared with controls (p values 0.004-0.038). Lower DTI-ALPS index, deep gray matter volume, and cortical volume could discriminate between patients and controls (R2 = 0.62), whereas lower DTI-ALPS index, higher number of myelitis, and higher T2-lesion volume were associated with worse disability (R2 = 0.55).

Interpretation: Patients with neuromyelitis optica spectrum disorder are characterized by abnormal enlargement and impaired water diffusion along the PVS, whose clinical implications suggest a direct correlation with disease pathogenesis and severity. ANN NEUROL 2022;92:173-183.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aquaporin 4
  • Atrophy
  • Diffusion Tensor Imaging / methods
  • Humans
  • Magnetic Resonance Imaging / methods
  • Neuromyelitis Optica* / diagnostic imaging


  • Aquaporin 4