FIG 2. Graph of the velocities (in mm/s) at each of 14 time points in the cardiac cycle in each voxel in the subarachnoid space for TC (left) and MS (right) before (top row) and after (bottom row) decompression of the craniocervical junction. Time courses of voxels in the anterior subarachnoid space are colored red, and those in the posterior subarachnoid space colored green. Note that the velocities in a cephalad direction (positive values) are reduced following decompression. Velocities in the anterior subarachnoid space are more affected than those in the posterior subarachnoid space.