Introduction CADASIL is characterised by cerebral vascular dysfunction, with hypoperfusion the likely cause of stroke and dementia. The phenotypic variability means clinically relevant imaging biomarkers are needed. Arterial spin labelling (ASL) MRI is a repeatable and quantifiable method of imaging cerebral blood flow (CBF).

Methods Adults with genetically proven CADASIL underwent ASL to measure CBF at baseline and 1 year later. Anatomical sequences were also acquired. CBF maps were created in Image J. A slice of brain above the centrum semiovale was segmented into grey matter (GM) and deep white matter (WM) masks. Paired t-tests and Spearman rank correlation were used. Results are expressed as mean (SD).

Results 22 participants were recruited. GM CBF was 52 (±11), and WM 27 (5) ml/100 g/min. Age correlated to GM CBF (n=22, rs=−0.492, p=0.02). CBF declined over one year in both GM (11%, p=0.03) and WM (7%; p=0.04) masks.

Conclusion CBF in CADASIL patients declines faster than is reported for healthy individuals. This is the first study to show ASL is a feasible method to study CBF in CADASIL and has demonstrated changes over the time period which may be suitable for a clinical trial.