title: The influence of the input function on quantitative rCBF by the Xe/CT method.
abstract: Measurements of rCBF by the Xe/CT method are based on the assumption of identity between the end-tidal xenon curve which is applied as input function, and the arterial xenon curve being the true input function to the brain. In this study corresponding end-tidal and arterial xenon curves were measured in an experimental animal model (part 1) and in 5 patients with traumatic brain injury (part 2) and used for rCBF calculation. In both studies rCBF was underestimated by using the end-tidal xenon concentration curve as brain input function. In part 1 rCBF underestimation was depended on pulmonary gas exchange; high or low levels of rCBF; tissue type; and xenon inhalation protocols. In part 2 the mean rCBF underestimation was 18.8 +/- 8.3%. In conclusion, non-invasive estimate of the input function should be considered as a source of error when defining quantitative blood flow values e.g. the flow thresholds of ischaemic infarction.
authors.affiliation: Dept. of Neurosurgery, Aarhus University Hospital, Denmark.
authors.forename: G
authors.initials: G
authors.lastname: von Oettingen
authors.forename: B
authors.initials: B
authors.lastname: Bergholt
authors.forename: L
authors.initials: L
authors.lastname: Ostergaard
authors.forename: M
authors.initials: M
authors.lastname: Rasmussen
authors.forename: C
authors.initials: C
authors.lastname: Gyldensted
authors.forename: J
authors.initials: J
authors.lastname: Astrup
mesh_terms: D000818:Animals; D001930:Brain Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D006801:Humans; D055370:Lung Injury; D008297:Male; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014978:Xenon
chemical_list: D014978:Xenon