Multiple sclerosis (MS) is primarily an inflammatory demyelinating disease of the central nervous system. However, there is also growing evidence that cortical dysfunction may also be associated with disability in MS. Few studies have investigated cortical cerebral perfusion in MS, and even fewer have utilised arterial spin labelling (ASL) MRI, which offers noninvasive quantitative assessment of cerebral function using endogenous contrast. ASL is an inherently low resolution imaging modality known to be affected by the partial volume (PV) effect, leading to an underestimation of grey matter (GM) perfusion. Decreases in GM perfusion could reflect neuronal loss or metabolic dysfunction; PV correction techniques allow decoupling of structure and function. It is hypothesized that reduced regional GM perfusion after PV correction reflects a genuine decreased tissue metabolism, rather than atrophy.