Xenon-induced flow activation in patients with cerebral insult who undergo xenon-enhanced CT blood flow studies

BACKGROUND AND PURPOSE: Stable xenon–enhanced CT (sXe/CT) has gained wide ac-ceptance in the assessment of regional cerebral blood flow (rCBF) in patients with intracranial abnormalities. The aim of this study was to test whether the contrast medium (ie, sXe) itself directly induces relevant changes in rCBF, thereby distorting any valid determination of ce-rebral perfusion by using sXe/CT. METHODS: To characterize the degree and temporal dynamics of sXe-induced flow acti-vation, a thermal diffusion (TD)-based microprobe was placed subcortically into the frontal lobe on either hemisphere to assess rCBF (TD-rCBF) continuously in 23 patients (mean age, 55 6 18 years) with severe intracranial insult who were undergoing sXe/CT. RESULTS: In 35, the sXe/CT studies TD-rCBF rose from 25 6 17 mL/100 g per minute (range, 5–42 mL/100 g per minute) before sXe administration to 28 6 21 mL/100 g per minute (range, 6–46 mL/100 g per minute) after arterial sXe saturation was reached. Analysis of the flow activation curve showed a logarithmic shape with an increase in TD-rCBF between 3% and 7 % within the first 76 seconds of sXe wash-in (12 % after 190 seconds) and showed no further augmentation until the end of the blood flow study