NONINVASIVE MEASUREMENT OF REGIONAL CEREBRAL BLOOD-FLOW CHANGE WITH (H2O)-O-15 AND POSITRON EMISSION TOMOGRAPHY USING A MECHANICAL INJECTORAND A STANDARD ARTERIAL INPUT FUNCTION

To estimate changes in regional cerebral blood flow (rCBF) without art erial sampling in the study of functional-anatomical correlations in t he hunan brain, using O-15-labeled water and PET, a standard arterial input function was generated from the Input function in 10 normal volu nteers with dose calibration and peak time normalization. The speed an d volume of injection were precisely controlled with a mechanical inje ctor. After global normalization of each tissue activity image, the st andard arterial input function was applied to obtain estimated CBF ima ges. Relative changes in estimated rCBF to whole brain mean CBF(Delta Fest) and those in regional tissue activity (Delta C) were compared wi th true relative rCBF changes (Delta F) in 40 pairs of images obtained from 6 normal volunteers. Delta Fest correlated web with Delta F, whe reas Delta C consistently underestimated Delta F. This noninvasive met hod simplifies the activation studies and provides the accurate estima tion of relative how changes.