Gait apraxia has attributed to ventriculomegaly and periventricular leukoariaosis. Geometric quantification of ventriculomegaly using Evans’ Index (EI) and Callosal Angle (CA) have been proposed as biomarkers of normal pressure hydrocephalus (NPH). The novel Splenial Angle (SA) may aid in differentiating healthy controls (C) and Parkinson's Disease (P) patients from those with postural instability and gait difficulty (G) subtype and NPH. CA and SA are significantly lower in G patients compared to C and P while EI is significantly higher. Automation of these geometric measures is relatively accurate for EI and SA but further improvements are needed for CA.