Most small cerebral cortical veins demonstrate significant flow pulsatility: a human phase contrast MRI study at 7T

Abstract

<jats:title>Abstract</jats:title><jats:p>Phase contrast MRI has been used to investigate flow pulsatility in cerebral arteries, larger cerebral veins and the cerebrospinal fluid. Such measurements of intracranial pulsatility and compliance are beginning to inform understanding of the pathophysiology of conditions including normal pressure hydrocephalus, multiple sclerosis and dementias. We demonstrate the presence of flow pulsatility in small cerebral cortical veins, for the first time using phase contrast MRI at 7 Tesla, with the aim of improving our understanding of the haemodynamics of this little-studied vascular compartment. An automated method for establishing where venous flow is pulsatile is introduced, revealing significant pulsatility in 116 out of 146 veins, across 8 healthy participants, assessed in parietal and frontal regions. Distributions of pulsatility index and pulse waveform delay were characterized, indicating a small, but statistically significant (p&lt;0.05), delay of 59±41 ms in cortical veins with respect to the superior sagittal sinus, but no differences between veins draining different arterial supply territories. Measurements of pulsatility in smaller cortical veins, a hitherto unstudied compartment closer to the capillary bed, could lead to a better understanding of intracranial compliance and cerebrovascular (patho)physiology.</jats:p>

Non‐Invasive Assessment of Damping of Blood Flow Velocity Pulsatility in Cerebral Arteries With MRI

“…First, the PC sequence is relatively sensitive to motion during scanning. This can result in severe motion artifacts and give unreliable velocity and pulsatility measurements 39 . This led to a considerable number of subjects to be excluded from small perforating artery analysis for the CSO level and BG level.…”

“…This can result in severe motion artifacts and give unreliable velocity and pulsatility measurements. 39 This led to a considerable number of subjects to be excluded from small perforating artery analysis for the CSO level and BG level. This high exclusion rate is also known from earlier studies 7,9 and so far no quality assessment method has been developed to objectively exclude PC images from analysis.…”

Anatomical atlas of the upper part of the human head for electroencephalography and bioimpedance applications

“…Venous blood is drained to the jugular veins via cerebral sinuses, while CSF moves in the subarachnoid space and leaves/returns to the cavity via the foramen magnum to balance intracranial pressure waves during the cardiac cycle (Greitz et al 1992, Sakka et al 2011. Recently, pulsatility was also observed in small cortical veins (Driver et al 2020), and studies in rats show that the flow in microvessels is quasi-steady laminar flow, following Hagen-Poiseuille law expected in low Reynolds and Womersley numbers (Seki et al 2006).…”