Abstract
AbstractBackgroundVertebral artery hypoplasia (VAH) is an anatomical variation that may be associated with lower cerebral blood flow. We demonstrated the prevalence of VAH to be approximately 26% in a pilot study of healthy adults (n = 39). The purpose of this study was to expand on these findings by determining the prevalence of VAH and its impact on cerebral hemodynamics in a larger sample size of middle‐aged and older adults.MethodA total of 550 participants (66 ± 9 years; 346 females) underwent 4D flow MRI scans to evaluate the internal carotid arteries (ICA), vertebral arteries, and basilar artery. VAH+ (positive for VAH) was determined from the 4D flow MRI scans using both diameter (<2.5 mm) and flow (<47 mL/min).ResultWe identified 152 participants as VAH+ (prevalence of 28%). The prevalence of VAH+ was similar between females (n = 95; 27%) and males (n = 57; 28%). VAH predominantly occurred in the right vertebral artery (n = 102; 67%). As expected within VAH+ participants, the hypoplastic vertebral artery diameter was smaller (2.0±0.2 mm vs. 2.8±0.5 mm; p<0.001), blood flow was lower (29±10 ml/min vs. 100±44 ml/min; p<0.001), and pulsatility index was higher (1.8±0.6 a.u. vs. 1.3±0.3 a.u.; p<0.001) compared to the contralateral artery. There were no differences in ICA diameter (p = 0.875), blood flow (p = 0.553) or pulsatility index (p = 0.984) between VAH+ and no VAH. When evaluating the basilar artery, the diameter was smaller (2.7±0.4 mm vs. 2.8±0.4 mm; p = 0.037) with lower blood flow (105±35 ml/min vs. 116±37 ml/min; p<0.001) in VAH+ compared with no VAH. Males with VAH+ had higher basilar artery pulsatility index compared with males with no VAH (1.4±0.4 a.u. vs. 1.2±0.3 a.u.; p = 0.004), but this was not apparent in females (p = 0.544). When comparing global cerebral blood flow, there was a trend for lower flow in VAH+ compared with no VAH (p = 0.096).ConclusionWe demonstrated VAH prevalence to be around 28%, with similar prevalence in both males and females. VAH was associated with impaired regional flow and with elevated basilar artery cerebral pulsatility in males.
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