²Second goal is to
mark inferior edge of PC
åThis is harder,
since PC doesnÕt show up well at 1 mm resolution
åFortunately, PC is
always at the top of the cerebral aqueduct, which does show up well (at least, if
CSF is properly suppressed by the MRI pulse sequence)
åTherefore, if you
canÕt see the PC, find mid-sagittal location just at top of cerebral aqueduct and mark
it as [PC inferior edge]
²Third goal is to
mark two inter-hemispheric
points (above corpus callosum)
åThe two points must
be at least 2 cm apart
åThe two planes
AC-PC-#1 and AC-PC-#2 must be no more than 2o apart