Metrizamide washout as a measure of CSF bulk flow

Summary Metrizamide was injected into the ventricular system of three adults and five children with indwelling ventricular catheters and subcutaneous CSF reservoirs. A first-order rate constant, k, for metrizamide washout from one lateral ventricle was determined with reference to ventricular metrizamide concentration on serial (up to six) postinjection CT scans. Lateral ventricular volume, V_v, was estimated after metrizamide injection by a planimetric method and by partial volume analysis, an interactive computerized technique. The rate of lateral ventricular CSF formation, I_f, was calculated as kxV_v and ranged from 0.0622 to 0.103 ml/min. precise measurements of lateral ventricular CSF bulk flow depend upon adquate mixing of the injected contrast material with ventricular CSF and accurate measurements of lateral ventricular volume.