Takizawa K, et al. - This study seeks to quantitatively assess the velocities and displacements of the waveforms of the two motions (cardiac- and respiratory-driven cerebrospinal fluid motion) based on an asynchronous two-dimensional (2D) phase-contrast (PC) method followed by frequency component analysis. In this study, asynchronous 2D-PC magnetic resonance imaging (MRI) was performed under respiratory guidance to separate cardiac- and respiratory-driven CSF motions. For velocity, the cardiac component was greater than the respiratory component. On the other hand, the respiratory component was greater for the amount of displacement.