23 Sep 20. Featured Paper

Quantitative measurements of enlarged perivascular spaces in the brain are associated with retinal microvascular parameters in older community-dwelling subjects.

Link to paper on Cerebral Circulation - Cognition & Behavior.

Authors

Lucia Ballerini, Sarah McGrory, Maria del C.Valdés Hernández, Ruggiero Lovreglio, Enrico Pellegrini, Tom MacGillivray, Susana Muñoz Maniega, Ross Henderson, Adele Taylor, Mark E. Bastin, Fergus Doubal, Emanuele Trucco, Ian J. Deary, Joanna Wardlaw

Abstract

Background: Perivascular Spaces (PVS) become increasingly visible with advancing age on brain MRI, yet their relationship to morphological changes in the underlying microvessels remains poorly understood.

Retinal & cerebral microvessels share morphological & physiological properties.

We compared computationally-derived PVS morphologies with retinal vessel morphologies in older people.

Methods: We analysed data from community-dwelling individuals who underwent multimodal brain MRI & retinal fundus camera imaging at mean age 72.55 years (SD=0.71).

We assessed centrum semiovale PVS computationally to determine PVS total volume & count, & mean per-subject individual PVS length, width & size.

We analysed retinal images using the VAMPIRE software suite, obtaining the Central Retinal Artery & Vein Equivalents (CRVE & CRAE), Arteriole-to-Venule ratio (AVR), & fractal dimension (FD) of both eyes.

We investigated associations using general linear models, adjusted for age, gender, & major vascular risk factors.

Results: In 381 subjects with all measures, increasing total PVS volume & count were associated with decreased CRAE in the left eye (volume β=−0.170, count β=−0.184, p<0.001).

No associations of PVS with CRVE were found.

The PVS total volume, individual width & size increased with decreasing FD of the arterioles (a) & venules (v) of the left eye (total volume: FDa β=−0.137, FDv β=−0.139, p<0.01; width: FDa β=−0.144, FDv β=−0.158, p<0.01; size: FDa β=−0.157, FDv β=−0.162, p<0.01).

Conclusions: Increase in PVS number & size visible on MRI reflect arteriolar narrowing & lower retinal arteriole & venule branching complexity, both markers of impaired microvascular health.

Computationally-derived PVS metrics may be an early indicator of failing vascular health & should be tested in longitudinal studies.

Keywords

• Ageing

• MRI

• Perivascular spaces

• Retina