Velocity Pulsatility and Arterial Distensibility Along the Internal Carotid Artery

Abstract

Background Attenuation of velocity pulsatility along the internal carotid artery (ICA) is deemed necessary to protect the microvasculature of the brain. The role of the carotid siphon within the whole ICA trajectory in pulsatility attenuation is still poorly understood. This study aims to assess arterial variances in velocity pulsatility and distensibility over the whole ICA trajectory, including effects of age and sex. Methods and Results We assessed arterial velocity pulsatility and distensibility using flow‐sensitized 2‐dimensional phase‐contrast 3.0 Tesla magnetic resonance imaging in 118 healthy participants. Velocity pulsatility index (vPI=(V max −V min )/V mean ) and arterial distensibility defined as area pulsatility index (A max −A min )/A mean ) were calculated at C1, C3, and C7 segments of the ICA. vPI increased between C1 and C3 (0.85±0.13 versus 0.93±0.13, P <0.001 for averaged right+left ICA) and decreased between C3 and C7 (0.93±0.13 versus 0.84±0.13, P <0.001) with overall no effect (C1–C7). Conversely, the area pulsatility index decreased between C1 and C3 (0.18±0.06 versus 0.14±0.04, P <0.001) and increased between C3 and C7 (0.14±0.04 versus 0.31±0.09, P <0.001). vPI in men is higher than in women and increases with age ( P <0.015). vPI over the carotid siphon declined with age but remained stable over the whole ICA trajectory. Conclusions Along the whole ICA trajectory, vPI increased from extracranial C1 up to the carotid siphon C3 with overall no effect on vPI between extracranial C1 and intracranial C7 segments. This suggests that the bony carotid canal locally limits the arterial distensibility of the ICA, increasing the vPI at C3 which is consequently decreased again over the carotid siphon. In addition, vPI in men is higher and increases with age.

Blood Flow Velocity Pulsatility and Arterial Diameter Pulsatility Measurements of the Intracranial Arteries Using 4D PC-MRI

“…This intersubject variation is likely a combined effect of both physiological differences and measurement errors. Taking an average pulse pressure of 40 mmHg for healthy volunteers, the aPI at C7 (where the vessel is not hampered by the bony carotid canal, as is the case for C3) corresponds to an arterial distensibility of 0.50%/mmHg, which corresponds well with values reported for the intracranial arteries (Giannattasio et al, 2008;Studinger et al, 2003;van Tuijl et al, 2020;Warnert et al, 2015). We observed that the measured blood flow rate between the C3 and C7 was largely preserved.…”

“…We observed that the measured blood flow rate between the C3 and C7 was largely preserved. This shows that our proposed software correctly captures the variation in arterial lumen area and blood flow velocity pulsatility that exists along the distal end of the carotid artery (Schubert et al, 2011;van Tuijl et al, 2020). In most cases, the blood flow rate was slightly lower at the C7 level.…”

Association of Vascular Properties With the Brain White Matter Hyperintensity in Middle‐Aged Population

“…We postulate the reason for the lack of association of PVWMH volume with CCA distensibility coefficient is potentially attributable to the special location of CCA and its bifurcation, which may limit distensibility and its measurement because of the carotid bony canal. 43 Finally, PVWMH volume was not associated with cardiac function in our cohort, which is likely a reflection of the healthy status of our middle‐aged population without a known cardiac disease.…”

Diffuse idiopathic skeletal hyperostosis is associated with incident stroke in patients with increased cardiovascular risk

“…People prone to bone formation may form these calcifications more easily. Intracranial calcifications are common and may result in higher pulsatility, which may be detrimental for ‘soft organs’ such as the brain [ 27 ].…”