Experimental xenon enhancement with CT imaging: Cerebral applications

Xenon-enhanced cranial computed tomography (CT) was used to derive the partition coefficient (λ) and flow rate constant (K) and thus provide a functional neuroanatomic map of local cerebral blood flow in eight nonhuman primates. Sequential CT imaging defined the temporal changes of xenon concentration in arterial blood and brain tissue both during and after xenon inhalation. Several methodologies including clearance, buildup, and in vivo 'autoradiography' were used to estimate flow in various brain locales. A typical derived fast flow rate using xenon CT methodology was 85 ml/100 g/min, with a range of 58-108. The in vivo autoradiographic method of defining flow seems more clinically applicable in man. The limitations and potential solutions using CT blood flow techniques are discussed.