BRAIN AND CEREBROSPINAL-FLUID MOTION - REAL-TIME QUANTIFICATION WITH M-MODE MR-IMAGING

PURPOSE: To assess motion of brain parenchyma and cerebrospinal fluid (CSF) with magnetic resonance (MR) phase imaging in real time. MATERIA LS AND METHODS: Repetitive excitation of a cylinder with two-dimension al selective excitation followed by one-dimensional imaging along the cylinder axis yielded profiles analogous to those of M-mode echography . Bipolar gradients provided velocity sensitivity in an arbitrary spat ial direction. RESULTS: Brain and CSF of healthy volunteers exhibited periodic motion in the frequency range of normal heart rate. Both brai n hemispheres showed periodic squeezing of the ventricles, with peak v elocities up to 1 mm/sec followed by a slower recoil. Superimposed on the regular displacement of the brain stem was a slow, respiratory-rel ated periodic shift of the neutral position. During the Valsalva maneu ver, the brain stem showed initial caudal and subsequent cranial displ acement of 2-3 mm. Coughing produced a short swing of CSF in the cepha lic direction. CONCLUSION: Real-time MR phase imaging allows observati on of nonperiodic events in brain and CSF motion.