Submitted: 16 September 2026 Posted: 16 September 2026 You are already at the latest version Arterial spin labelling (ASL) MRI provides a noninvasive measure of cerebral perfusion, raising the possibility of distinguishing Parkinson's disease (PD) from atypical parkinsonian syndromes (corticobasal syndrome, multiple system atrophy, progressive supranuclear palsy) and of separating the associated cognitive disorders, PD dementia and dementia with Lewy bodies (DLB), from Alzheimer's disease (AD).