Introduction and Purpose The cerebral circulation is highly regulated to maintain brain perfusion, keeping an equilibrium between brain tissue, cerebrospinal fluid (CSF) and blood of the arterial and venous systems. Cerebral venous drainage abnormalities have been implicated in multiple cerebrovascular diseases. The purpose of this study is to evaluate the relationship between arterial inflow (AI) and cerebral venous outflow (CVO) and their correlation with cardiac outflow in healthy adults and children to understand the role of emissary veins in normal venous drainage.

Materials and Methods 31 healthy volunteers (24 adults (39.5±16.0) and 7 children (3.4±2.2)) underwent intercardinal 4D flow with full Circle of Willis coverage and 2D PC-MRI at the level of the transverse sinus for measurement of AI and CVO, respectively. AI was calculated as the sum of flow values in the bilateral internal carotid and basilar arteries. CVO was calculated as the sum of flow values in the bilateral transverse sinuses. Cardiac outflow was measured on 2D-PC MRI with retrospective ECG gating with images acquired at the proximal ascending aorta (AAo) and descending (DAo) aorta. The ratio of AI/AAo flow and CVO/AI were calculated to characterize the fraction of cerebral arterial inflow in relation to cardiac outflow and venous blood draining through transverse sinuses, respectively.

Using a univariate analysis with a nonparametric Mann-Whitney test, the ratios of the cerebral venous outflow and arterial inflows were compared between adults and children. Spearman coefficient’s test was utilized to determine correlation between flow parameters and age. The level for statistical significance (P-value) was set at 0.05.

Results AI and CVO were significantly correlated (r=0.81, P< 0.001). There was a trend towards increased cerebral arterial inflow from birth to the age of 8 years (r = 0.71, P = 0.072), then there was a significant decrease in cerebral arterial inflow from the age of 19 afterwards (r = -0.69, P < 0.001). The cerebral venous outflow increased significantly from birth till the age of 7 years (r = 0.89, P = 0.007), then decreases slowly from 19 years afterwards (r = -0.29, P = 0.171). CVO constituted approximately 60–70% of AI. The CVO/AI ratio was significantly lower in children versus adults (P=0.025).

Conclusion The CVO/AI ratio suggests an important role of emissary veins accounting for approximately 30–40% of venous drainage. The lower CVO/AI ratio in children, although partially related to decrease AI in age, suggests a greater role of emissary veins in childhood that strongly decreases with age.

Disclosures R. Abdalla: None. S. Schnell: None. M. Aristova: 1; C; NIH F30 HL140910. M. Alzein: None. Y. Moazeni: None. J. Aw: None. C. Wu: None. M. Markl: None. D. Cantrell: None. M. Hurley: None. S. Ansari: None. A. Shaibani: 1; C; NIH T32 GM815229 (Northwestern), American Heart Association (AHA) Predoctoral Fellowship 14PRE18370014, Radiological Society of North America (RSNA) Research Seed Grant RSD1207.