Mapping local blood flow of human brain by CT scanning during stable xenon inhalation.

Abstract

SUMMARY Non-invasive methods are described for estimating local cerebral blood flows (LCBF) and partition coefficients (LX) during inhalation of 35% stable xenon gas (Xe*) in oxygen during CT scanning. After denitrogenatioD by 100% oxygen breathing, 35% Xe* is breathed for 7-8 minutes to minimize subanestbetic effects. Mean changes in brain Hounsfleld units extrapolated to 15 minutes were 7.7 units for white matter and S3 units for gray matter. They were measured from volumes 80 cubic mm (10 mm* area X 8 mm), or larger with an EMI 1010 scanner at 1 minute intervals. These data were used for computing LCBFs and LXs. Irradiation measured at the center of brain slices was 1 rad per minute. To calculate LXs about 6 exposures are necessary, thereafter, each 1 minute scan provides LCBF measurements for 2 adjacent 8 mm slices.

Identifying systematic errors in quantitative dynamic‐susceptibility contrast perfusion imaging by high‐resolution multi‐echo parallel EPI

“…The observed decline of the GM-WM contrast (CBV GM /CBV WM and CBF GM /CBF WM ) with age has been reported previously (1). In comparison to literature values from different modalities ( 15 O PET, Xe CT, DSC-MRI, T 1 -weighted MRI, I CT) (1,(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28), which provide CBV and CBF values listed in Table 2, roughly, a factor 4 overestimation is observed.…”

Regional cerebral blood flow of patients with focal epilepsy studied using xenon enhanced CT brain scanning.

“…In agreement with previous workers2 3 we found that XeCT was tolerated reasonably well. During xenon inhalation five patients became lightheaded, and one felt as though she was looking down a yellow tunnel.…”

“…Stable xenon-enhanced X-ray computed tomography (XeCT) has previously been used to measure regional cerebral blood flow (rCBF) in normal subjects,' and patients with cerebrovascular disease.2 3 In a group of 19 resting normal subjects no significant differences between the rCBF of left and right cerebral structures were found.' To date there have been no reported measurements using XeCT of rCBF in patients with focal epilepsy.…”

Progress in cerebrovascular disease: local cerebral blood flow by xenon enhanced CT.

“…Recent observations have indicated that EEG alterations do occur during xenon inhalation. 37 Our preliminary data on changes in LCBF during prolonged inhalations indicate that there is a gradual but slow decrease in blood flow of approximately 25% at 8 minutes. A significant reduction (x 2 to 3) in LCBF during the first few minutes of inhalation of high xenon concentrations (-80%) has been reported 22 but these results have been criticized in that mixed flows may have contributed to these observations.…”