Transverse cerebral MRI section (T2-weighted, 1.5 Tesla) at level Z = 0, from a 51-year-old male, showing measurement of the AC-PC length. 1: AC-PC length, 2: AC, 3: third ventricle, 4: temporal lobe, 5: frontal lobe, 6: insula, 7: Sylvian fissure, A: anterior, P: posterior and, R: right, L left.