Methods for determining blood flow in the brain — Part II: Stable xenon/CT method

In this paper, the stable Xenon/CT technique for measuring cerebral blood flow (CBF) is described in detail. Particular emphasis is placed on discussing the basic methodology of the technique and the recent improvements implemented by the authors. These improvements include the maintenance of the carbon dioxide concentration in the exhaled air, the continuous monitoring of oxygen and carbon dioxide, a double exponential approximation to the xenon uptake by the arterial blood, and a consideration of the transit time of xenon from the lungs to the brain. Full automation of the collection and processing of all arterial data further enhances the accuracy of the measurement. Comparison of this technique with the established radiolabelled microspheres technique shows that the agreement between both methods is high over a wide range of blood flow values. With a reduction in the X-ray and xenon exposure, this technique promises to be the foremost cerebral blood flow technique for the next several years.