In vivo Measurement of the Volume of Distribution of Water in Cerebral Grey Matter: Effects on the Calculation of Regional Cerebral Blood Flow

The present study was undertaken to determine the apparent value for the volume of distribution of water to be used in the dynamic/integral technique for generating functional CBF images. A value of 0.86 resulted in only a minor loss of accuracy compared to the more accurate (but time-consuming) dynamic only analysis, which incorporated the regionally fitted estimates of the volume of distribution of water. In contrast to the traditionally used in vitro value of 0.95, the value of 0.86 allows for the inclusion of a significant part of the washout phase in the integral analysis, thereby producing statistically improved CBF images.