Purpose The aim of this study was to determine the occurrence and distribution 
of the 'central vein' sign in white matter lesions on susceptibility-weighted 
magnetic resonance images in patients with multiple sclerosis (MS) and cerebral 
small vessel disease (CSVD). Materials and methods T2-weighted and 
fluid-attenuated inversion recovery magnetic resonance images of 19 MS patients 
and 19 patients affected by CSVD were analysed for the presence and localisation 
of focal hyperintense white matter lesions. Lesions were subdivided into 
periventricular or non-periventricular (juxtacortical, subcortical, deep white 
matter and cerebellar) distributed. The number and localisation of lesions 
presenting with the central vein sign were recorded and compared between MS and 
CSVD lesions. Results A total of 313 MS patients and 75 CSVD lesions were 
identified on T2-weighted and fluid-attenuated inversion recovery magnetic 
resonance images. The central vein sign was found in 128 MS lesions (40.9%), and 
the majority of them (71/128, 55.5%) had a periventricular distribution. The 
central vein sign was found in 22 out of 75 (29.3%) CSVD lesions, and 
periventricular distribution was seen in six out of 22 (27.2%) CSVD lesions. The 
difference in the proportion of white matter hyperintense lesions that presented 
with the central vein sign on susceptibility-weighted images in patients with MS 
and CSVD was statistically different, and a significantly higher number of MS 
patients presented with lesions with the central vein sign compared to CSVD 
patients. Conclusion The presence of the central vein sign on 
susceptibility-weighted images for MS lesions improves the understanding of the 
periventricular distribution of MS lesions and could contribute as adjunctive 
diagnostic criteria for MS disease.