Assessing CSF secretion by measuring net velocity of CSF in the human subarachnoid space using displacement encoding with stimulated echoes at 7T.

Continuous secretion and absorption of cerebrospinal fluid (CSF) cause a net velocity that is important for cerebral clearance. However, measuring this net velocity is hampered by the cardiac and respiratory cycle which induce additional CSF motions. We show, with both simulations and in vivo measurements, that net velocity of CSF in the subarachnoid space can be measured using displacement encoding with stimulated echoes (DENSE), when contributions from heartbeat and respiration are accounted for during the analysis. Measured net velocity was 4.41±1.57 µm/s (6 subjects). Further research is needed to properly account for possible phase wraps in the measurements.