Noninvasive measurement of regional cerebral blood flow change with H215O and positron emission tomography using a mechanical injector and a standard arterial input function

To estimate changes in regional cerebral blood flow (rCBF) without arterial sampling in the study of functional-anatomical correlations in the human brain, using ¹⁵O-labeled water and PET, a standard arterial input function was generated from the input function in 10 normal volunteers with dose calibration and peak time normalization. The speed and volume of injection were precisely controlled with a mechanical injector. After global normalization of each tissue activity image, the standard arterial input function was applied to obtain estimated CBF images. Relative changes in estimated rCBF to whole brain mean CBF(ΔFest) and those in regional tissue activity (ΔC) were compared with true relative rCBF changes (ΔF) in 40 pairs of images obtained from 6 normal volunteers. ΔFest correlated well with ΔF, whereas ΔC consistently underestimated ΔF. This noninvasive method simplifies the activation studies and provides the accurate estimation of relative flow changes