Background: A classification of cardiac-and respiratory-driven components of cerebrospinal fluid (CSF) motion has been demonstrated using echo planar imaging and time-spatial labeling inversion pulse techniques of magnetic resonance imaging (MRI). However, quantitative characterization of the two motion components has not been performed to date. Thus, in this study, the velocities and displacements of the waveforms of the two motions were quantitatively evaluated based on an asynchronous two-dimensional (2D) phase-contrast (PC) method followed by frequency component analysis. Methods:The effects of respiration and cardiac pulsation on CSF motion were investigated in 7 healthy subjects under guided respiration using asynchronous 2D-PC 3-T MRI. The respiratory and cardiac components in the foramen magnum and aqueduct were separated, and their respective fractions of velocity and amount of displacement were compared.Results: For velocity in the Sylvian aqueduct and foramen magnum, the fraction attributable to the cardiac component was significantly greater than that of the respiratory component throughout the respiratory cycle. As for displacement, the fraction of the respiratory component was significantly greater than that of the cardiac component in the aqueduct regardless of the respiratory cycle and in the foramen magnum in the 6-and 10-s respiratory cycles. There was no significant difference between the fractions in the 16-s respiratory cycle in the foramen magnum. Conclusions:To separate cardiac-and respiratory-driven CSF motions, asynchronous 2D-PC MRI was performed under respiratory guidance. For velocity, the cardiac component was greater than the respiratory component. In contrast, for the amount of displacement, the respiratory component was greater.
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.
To investigate spatial distribution properties of the cardiac- and respiratory-driven cerebrospinal fluid (CSF) motions in the intracranial space, correlation mapping technique was conducted. Time series of CSF velocity were acquired in 7 healthy subjects of 26±5 years old under by asynchronous 2-dimensional phase contrast (2D-PC) method with 217-msec temporal resolution. The delay time and maximum correlation maps of the cardiac- and respiratory-driven CSF motions demonstrated clear differences in the propagation properties. When the reference region was set at anterior spinal subarachnoid space, the maximum correlation coefficients in the case of 6-sec respiratory period were 0.91±0.05 for cardiac-driven and 0.78±0.08 for respiratory-driven. They were 0.90±0.06 and 0.81±0.06 in the case of 10-sec period. The cardiac- and respiratory CSF motions differently distributed in intracranial space.
To classify the cardiac- and respiratory-driven cerebrospinal fluid (CSF) motions, asynchronous 2D phase contrast (PC) of magnetic resonance imaging (MRI) with 217 ms time resolution in conjunction with power and frequency mapping was performed for 7 healthy subjects under respiration guidance. In the frequency domain, the cardiac-driven motion was at around 1.29±0.21 Hz and respiratory-driven motion was at 0.16±0.01 Hz under 6 sec respiratory cycle. Two different techniques were proposed for characterizing the motions; one was power-map (P-map) depicting integrated power spectrum in a selected band, and the other was frequency-map (F-map) delineating the frequency of maximum peak in power spectral density (PSD). These maps visualized the anatomical distributions of the two motions. Portions of the cardiac- and respiratory-driven CSF motions in the spinal subarachnoid space were 58.1±22.2 and 9.50±3.83 %, respectively. Power and frequency mapping clearly classified the cardiac-driven and respiratory-driven CSF motions.
Purpose: To characterize cardiac-and respiratory-driven cerebrospinal fluid (CSF) motions in intracranial space noninvasively, four-dimensional velocity mapping (4D-VM), correlation mapping, and power and frequency mapping with cardiac-gated and/or asynchronous magnetic resonance (MR) phase contrast (PC) techniques were conducted. Methods: Cardiac-gated PC in three spatial directions was applied to young, healthy, elderly, healthy, and idiopathic normal pressure hydrocephalus patient groups. 4D-VM was created from time-resolved 3D velocity distribution represented as vector and color coding. The curl and pressure gradient were calculated. Correlation mapping provides propagation delay and correlation of CSF motion at arbitrary points regarding a reference point. In addition, asynchronous PC technique was conducted for healthy volunteers with respiratory instruction as constant rhythm. Cardiac-and respiratory-driven velocities were separated by frequency analysis. Power and frequency mapping present both the energy and dominant frequency of cardiac or respiratory CSF motion. Results: 4D-VM, curl, pressure gradient images, and correlation mapping by cardiacgated PC demonstrated cardiac-driven CSF motion and its propagation properties. Power and frequency mapping, correlation mapping, and displacement analysis exhibited that the cardiac-driven CSF velocity was higher than the respiratory, although the cardiacdriven displacement was smaller. Conclusion: Visualization and characterization techniques based on PC imaging can capture the properties of CSF motion in intracranial space.
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