Abstract TP093: Age-related differences in heart and brain blood flow

Introduction: Changes in cardiac and cerebral blood flow (CBF) with aging may contribute to stroke and other cerebrovascular diseases. How cardiac flow affects CBF with age is not yet well understood. This research investigates aortic blood flow and CBF in healthy volunteers of different ages and studies the transitional change from young to older age. The purpose is to identify possible age-related differences in the heart and brain flow relationship. Methods: 15 volunteers (10 male, 5 female) from ages 20 to 44 were split into two groups, the younger 23.1 ± 2.8 and the older 38.5 ± 5.7 years (mean ± std). 4D Flow MRI images were sequentially acquired for the heart and brain for each volunteer using a Siemens 3.0 T scanner. An ECG-gated compressed sensing protocol (R=7.7) was used with a 1.4 mm and 2 mm voxel size for the brain and heart. The cerebral arteries near the Circle of Willis and thoracic aorta were imaged. 4D Flow MRI data were analyzed using Caas MR 4D Flow (Pie Medical Imaging BV, Maastricht, The Netherlands). We compared arterial volumetric flow and blood flow pulsatility over the cardiac cycle using pulsatility index (PI). Statistical analysis used Pearsons’ correlation coefficient (r). Results: In both groups, blood flows in different cerebral arteries were positively correlated (r > 0.5). Flow rates in the ICA and MCA arteries were highly correlated (r = 0.82), while the correlation decreased with distance (e.g. PCA and ACA, r = 0.41). Both groups showed a negative correlation between age and CBF, suggesting that brain blood flow decreases as people age. This effect was stronger among the older group (r = -0.58) than the younger group (r = -0.34). A negative correlation between CBF and cerebral PI was also observed in both groups. Unlike blood flow in the brain, which showed the same relationship trend in young and older groups, the relationship between aorta blood flow and CBF differed between the two groups. Among the younger group, aorta flow was not correlated with CBF (r = -0.09) and was correlated with cerebral PI (r = 0.3). The older group showed the opposite relationship; correlated with CBF (r = 0.55), and not with cerebral PI (r < 0.01). Conclusion: We observed correlations between CBF and cerebral PI in brain arteries. The correlation between blood flow in the aorta and CBF differed among the two age groups. These differences may reflect aging-related changes in the cardiovascular system, such as arterial stiffening.