Partial volume summation: a simple approach to ventricular volume determination from CT.

The accurate determination of ventricular volume from computed tomography (CT) is not a trivial problem. The direct approach of measuring the area within a visually determined boundary or contour level and multiplying by the nominal slice thickness may be subject to large errors because such boundaries are not, in general, well defined. When the ventricles are filled with a high-contrast material such as metrizamide, we may use the technique of 'partial volume summation,' a simple but accurate, clinically applicable method which may be performed on a standard DeltaScan-50 or similar system.