The influence of the input function on quantitative rCBF by the Xe/CT method.
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.
von Oettingen
G
G
Dept. of Neurosurgery, Aarhus University Hospital, Denmark.
Bergholt
B
B
Ostergaard
L
L
Rasmussen
M
M
Gyldensted
C
C
Astrup
J
J
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
D014978:Xenon