Detection of a relation between respiration and CSF pulsation with an echoplanar technique

The now of cerebrospinal fluid (CSF) through the aqueduct was studied with an echoplanar imaging technique. Images (1024) of a slice perpendicular to the aqueduct were acquired with a repetition time of 107 msec and a flip an gle of 90 degrees. This imaging technique is very sensitive for now into th e selected slice, although a quantitative assessment of now velocities is n ot possible. Simultaneously with the image data acquisition, data from a pu lse oximeter and a respiration belt were recorded. For each data point, a d elay time to the preceding cardiac pulse was determined from the recorded p ulse wave. The signal intensities could then be assigned to the cardiac cyc le. Each cardiac interval was assigned to one of eight respiratory phases, and an average signal curve during the cardiac interval was calculated for each respiration phase. The evaluation showed to signal maxima within the c ardiac interval, which could be identified as a downward now at 10% and an upward now at 80% of the cardiac pulse interval by measurements with additi onal saturation pulses, In examinations of 22 healthy volunteers, an influe nce of respiration on the now through the aqueduct was found. In spite of i nterindividual variability, comparable effects could be observed in all vol unteers. In the late expiration phase the caudally directed now was at its maximum, whereas the cranially directed flow was maximal in the post-inspir ation phase. (C) 2000 Wiley-Liss, Inc.