Objective:Cerebral microbleeds (MBs) are a common finding in cerebral small vessel disease (CSVD) and Alzheimer’s disease patients as well as in healthy elderly people, but their pathophysiology remains unclear. To investigate a possible role of veins in the development of MBs, we performed an exploratory study, assessing in vivo presence of MBs with a direct connection to a vein.Methods:7 Tesla (7 T) MRI was conducted and MBs were counted on Quantitative Susceptibility Mapping (QSM). A submillimeter resolution QSM-based venogram allowed identification of MBs with a direct spatial connection to a vein.Results:51 subjects (mean age [SD] 70.5[8.6] years, 37% females) participated in the study: 20 were patients with CSVD (cerebral amyloid angiopathy (CAA) with strictly lobar MBs (n=8), hypertensive arteriopathy (HA) with strictly deep MBs (n=5), and mixed lobar and deep MBs (n=7), 72.4 [6.1] years, 30% females) and 31 were healthy controls (69.4 [9.9] years, 42% females). In our cohort, we counted a total of 96 MBs with a venous connection, representing 14% of all detected MBs on 7T QSM. Most venous MBs (86%, n = 83) were observed in lobar locations and all of these were cortical. CAA subjects showed the highest ratio of venous to total MBs (19%) (HA=9%, mixed=18%, controls=5%)Conclusions:Our findings establish a link between cerebral MBs and the venous vasculature, pointing towards a possible contribution of veins to CSVD in general and to CAA in particular. Pathological studies are needed to confirm our observations.