Fig. 1.

Dynamic iMSDE SSFP images of an illustrative case. Dynamic iMSDE SSFP images of a 38-year-old women volunteer scanned in sagittal cross-section. The image with MSG off is subtracted from the image with MSG on. Areas of the scanned section in which movement is present are displayed as hypointense. The cerebral parenchyma is thus subtracted, and areas of the venous system in which perfusion is present are visualized as hypointense. Respiration-induced CSF motion in the fourth and third ventricles is visualized as hypointense. In the subarachnoid space at the anterior surface of the pons and medulla oblongata, turbulence due to CSF motion is apparent as a diminished MR signal. This site also reflects motion artifacts from movement of blood due to pulsation of the vertebral and basilar arteries. Due to concern that vascular motion artifacts may have interfered with analysis of CSF motion, an ROI was not designated at this site, and it was excluded from the analysis. Arrow: Wraparound artifact. iMSDE SSFP: improved motion-sensitized driven-equilibrium steady-state free precession, MSG: motion-sensitized gradient, CSF: cerebrospinal fluid, MR: magnetic resonance, ROI: region of interest