The clival-perpendicular or modified Water's view in compound tomography.

The air gap type of CT scanner with tilting gantry allows the use of head positions other than the standard semi-axial. The modified Water's or clival-perpendicular position is especially useful in the diagnosis of posterior fossa disease. The position offers a view that is approximately coronal to the clivus and tentorium. The clival-perpendicular view easily separates the supra- and infratentorial compartments. It also helps to differentiate extra- and intra-axial lesions and to locate the fourth ventricle, and it gives far better vertical orientation of posterior fossa pathology.