Cardiac-driven Pulsatile Motion of Intracranial Cerebrospinal Fluid Visualized Based on a Correlation Mapping Technique

Abstract

Purpose:A correlation mapping technique delineating delay time and maximum correlation for characterizing pulsatile cerebrospinal fluid (CSF) propagation was proposed. After proofing its technical concept, this technique was applied to healthy volunteers and idiopathic normal pressure hydrocephalus (iNPH) patients.Methods:A time-resolved three dimensional-phase contrast (3D-PC) sampled the cardiac-driven CSF velocity at 32 temporal points per cardiac period at each spatial location using retrospective cardiac gating. The proposed technique visualized distributions of propagation delay and correlation coefficient of the PC-based CSF velocity waveform with reference to a waveform at a particular point in the CSF space. The delay time was obtained as the amount of time-shift, giving the maximum correlation for the velocity waveform at an arbitrary location with that at the reference location. The validity and accuracy of the technique were confirmed in a flow phantom equipped with a cardiovascular pump. The technique was then applied to evaluate the intracranial CSF motions in young, healthy (N = 13), and elderly, healthy (N = 13) volunteers and iNPH patients (N = 13).Results:The phantom study demonstrated that root mean square error of the delay time was 2.27%, which was less than the temporal resolution of PC measurement used in this study (3.13% of a cardiac cycle). The human studies showed a significant difference (P < 0.01) in the mean correlation coefficient between the young, healthy group and the other two groups. A significant difference (P < 0.05) was also recognized in standard deviation of the correlation coefficients in intracranial CSF space among all groups. The result suggests that the CSF space compliance of iNPH patients was lower than that of healthy volunteers.Conclusion:The correlation mapping technique allowed us to visualize pulsatile CSF velocity wave propagations as still images. The technique may help to classify diseases related to CSF dynamics, such as iNPH.

Glymphatic imaging using MRI

“…One of the advantages of 4D‐PC is that this method can directly and noninvasively measure human intracranial arterial hemodynamics in individual subjects . The 4D‐PC method has also been used to quantify the spatiotemporal velocity distribution of CSF motion as vector cine images . The 4D‐PC technique can visualize the propagation of pulsatile CSF motion even in spaces separated by a thin membrane‐like structure through which no spin travels, such as the Liliequist membrane or an arachnoid cyst wall .…”

Neurofluid Dynamics and the Glymphatic System: A Neuroimaging Perspective

“…The phase-contrast method has also been utilized to visualize fluid flow. Recently, the visualization of CSF dynamics using four-dimensional phase-contrast (4D-PC) has been developed, which determines the quantitative spatiotemporal velocity distribution of CSF motion as vector cine images ( 47 ). One study using 4D-PC reported significantly lower CSF velocity in the posterior part of the lateral ventricle around the choroid plexus than that in other regions, a finding that challenged the traditional theory that choroid plexus pulsation is the driving force of CSF flow ( 48 ).…”

Visualization and Characterization of Cerebrospinal Fluid Motion Based on Magnetic Resonance Imaging

“…Cardiac-gated PC velocity measurement was performed in three spatial directions at 1.5 T for 13 young, healthy volunteers (8 males and 5 females with mean AE SD age of 29 AE 5); 13 elderly, healthy volunteers (4 males and 9 females with mean AE SD age of 72 AE 8); and 13 patients with iNPH (2 males and 11 females with mean AE SD age of 75 AE 5). Detailed imaging conditions are shown elsewhere [10].…”

“…After validating the appropriateness of the correlation mapping technique in a flow phantom [10], it was applied to three subject groups. The reference region was set at CSF near the basilar artery in the midline slice to visualize CSF motion propagation derived from the cardiac pulsation [9].…”

“…CSF motion is thought to be composed of three components: cardiac-driven motion, respiratory-driven motion, and bulk flow [7,8]. Cardiac-driven motion is primarily induced by arterial blood vessel pulsation and relates to the regulation of intracranial pressure (ICP) [2,4,9,10]. A change in intrathoracic pressure caused by respiration induces the modulation of venous blood pressure, resulting in respiratory-driven motion [6,[11][12][13][14].…”