Changes in Total Cerebral Blood Flow with Aging, Parenchymal Volume Changes, and Vascular Abnormalities: a Two-dimensional Phase-Contrast MRI Study

ABSTRACT

PURPOSE: To evaluate changes in total cerebral blood flow (tCBF) with aging, parenchymal volume changes and vascular abnormalities, using 2 dimensional (D) phase-contrast magnetic resonance imaging (PC MRI). MATERIALS AND METHODS: Routine brain MRI including T2 weighted image, time-of-flight (TOF) MR Angiography (MRA) and 2D PC MRI were performed in 73 individuals, including 12 volunteers. Normal subjects (12 volunteers, and 21 individuals with normal MRI and normal MRA) were classified into groups according to age (18 -29, 30 -49 and 50 -66 years). For the group with abnormalities in brain MRIs, cerebral parenchymal volume changes were scored according to the T2 weighted images, and atherosclerotic changes were scored according to the MRA findings. Abnormal groups were classified into 4 groups (i) mild reduction in volume, (ii) marked reduction in volume by parenchymal volume and atherosclerotic changes, and (iii) increased volume and (iv) Moya-moya disease. Volumetric flow was measured at the internal carotid artery (ICA) and vertebral artery bilaterally using the velocity-flow diagrams from PC MRI, and combined 4 vessel flows and tCBF were compared among all the groups. RESULTS: The age-specific distribution of tCBFs in normal subjects were as follows 12.0 +/- 2.1 ml/sec in 18 -29 years group, 11.8 +/- 1.9 ml/sec in 30 -49 years group, 10.9 +/-2.2 ml/sec in 50 -66 years group. The distribution of tCBFs in the different subsets of the abnormal population were as follows 9.5 +/-2.5 ml/sec in the group with mild reduction in volume, 7.6 +/-2.0 ml/sec in the group with marked reduction in volume, and 7.3 +/-1.2 ml/sec and 7.0 +/- 1.1 ml/sec in the increased parenchymal volume and Moya-moya disease groups respectively. CONCLUSION: Total cerebral blood flow decreases with increasing age with a concomitant reduction in parenchymal volumes and increasing atherosclerotic changes. It is also reduced in the presence of increased parenchymal volume and Moya-moya disease. 2D PC MRI can be used as a tool to evaluate tCBF with aging and in the presence of various conditions that can affect parenchymal volume and cerebral vasculature.