Alzheimer’s disease (AD) is the most common type of dementia in the elderly population. Although the leading pathological finding in AD is amyloid deposition in the brain, there is evidence that alterations of the cerebrovascular system might play a role in the development of the disease [1]. It has been shown that arterial pulsatility is increased in AD [1]; however, less information is available about changes in venous flow and venous pulsatility in individuals with AD [2]. Recent advances in MR hardware, data acquisition, and reconstruction have facilitated the use of 4D flow MRI in clinically feasible scan times. This approach enables both volumetric angiographic and quantitative assessment of blood flow velocities in a single acquisition. With adequate spatial and temporal resolution, 4D flow MRI seems ideally suited for comprehensive cranial hemodynamic assessment. The purpose of this study was to compare venous flow volume and pulsatility in an AD cohort and age matched controls. Using ECG-gated 4D flow MRI we test the hypothesis that AD related increased intracranial arterial pulsatility is transmitted through the arterioles and capillaries and that the venous system has also increased pulsatility. PI of the venous outflow may be a surrogate marker to the microvasculature that cannot be assessed with the current limits of spatial resolution.Subjects: The study population consisted of 25 AD patients (age range 57-89y, mean=71y, 11 F), and 25 older control adults (age range 66-85y, mean= 73y, 12 F). MRI: Volumetric, time-resolved phase contrast (PC) MRI data with 3-directional velocity encoding were acquired on a 3T clinical MRI system (MR750, GE Healthcare) with an 8 channel head coil (Excite HD Brain Coil, GE Healthcare), with a 3D radially undersampled sequence, PC VIPR [3] with the following imaging parameters Venc = 80 cm/s, imaging volume = 22x22x10 cm3, (0.7 mm)3 acquired isotropic spatial resolution, TR/TE=7.4/2.7ms, scan time ~ 7 min, retrospective cardiac gated into 20 cardiac phases with temporal interpolation of high spatial frequency k-space data [4]. Flow analysis: Automatic vessel segmentation and flow quantification was performed in a customized Matlab tool [5] (Mathworks, Natick, MA) from time maximum intensity projection (tMIP) dynamic PC MRAs reconstructed from the 4D flow data. The complete vascular tree was extracted using a centerline process, recording coordinates and labels for every branch. A centerline guided flow tracking algorithm was used to visualize and select the venous segments for further analysis. Flow rates were calculated for every selected branch by averaging flow data obtained in local cross-sectional cut-planes automatically placed in every centerline point perpendicular to the axial direction of the vessel. For this purpose 4 venous segments were selected (Fig. 1) (a, b, c): posteroinferior portion of the Superior Sagittal Sinus (SSS), middle segment of the Straight Sinus (STS), and the Transverse Sinus (TS)(left and right) segment just before the Sigmoid Sinus. Pulsatility index ($$$PI=\frac{Q_{max}-Q_{min}}{Q_{mean}}$$$) and mean blood flow were calculated and groups were compared with Student’s t-test (significance for p<0.05). Results for the vessel analysis are summarized in Figures 2-5. An increased PI in the AD group was found for all segments when compared with controls, with significant differences in all segments. The AD group also showed a decrease in blood flow for all the segments when compared with controls, with significant differences in all segments except in the STS segment.These results on the venous system resemble recent findings on the arterial system: AD patients have reduced blood flow and increased PI compared to age matched normal subjects. The significantly increased pulsatility in all segments in the AD cohort may reflect the primary cortical pathology of AD, and the associated arterial, arteriolar and capillary pulsatility alterations. These results are contrary to patients with vascular dementia, where a normal SSS pulsatility was reported [2]. A simple propagation from increased arterial pulsatility to the cortical veins and subsequently to the SSS in AD is less probable, as this should also be present in patients with vascular dementia.This study demonstrates the feasibility of hemodynamic analysis over a large vascular territory in the context of Alzheimer’s disease with 4D flow MRI within a 7-minute acquisition. Hemodynamic characteristics of the venous vascularity on AD group were investigated and compared to controls and significantly increased pulsatility was found in all segments of the AD cohort. With the large volume coverage and high temporal and spatial resolution demonstrated here, 4D flow MRI can provide additional biomarkers of vascular health that can contribute to identifying patients who could benefit from interventions to improve circulatory system functions.