title: Imaging local cerebral blood flow by Xenon-enhanced computed tomography--technical optimization procedures.
abstract: Methods are described for non-invasive, computer-assisted serial scanning throughout the human brain during eight minutes of inhalation of 27%-30% Xenon gas in order to measure local cerebral blood flow (LCBF). Optimized Xenon-enhanced computed tomography (XeCT) was achieved by 5-second scanning at one-minute intervals utilizing a state-of-the-art CT scanner and rapid delivery of Xenon gas via a face mask. Values for local brain-blood partition coefficients (L lambda) measured in vivo were utilized to calculate LCBF values. Previous methods assumed L lambda values to be normal, introducing the risk of systematic errors, because L lambda values differ throughout normal brain and may be altered by disease. Color-coded maps of L lambda and LCBF values were formatted directly onto CT images for exact correlation of function with anatomic and pathologic observations (spatial resolution: 26.5 cubic mm). Results were compared among eight normal volunteers, aged between 50 and 88 years. Mean cortical gray matter blood flow was 46.3 +/- 7.7, for subcortical gray matter was 50.3 +/- 13.2 and for white matter was 18.8 +/- 3.2. Modern CT scanners provide stability, improved signal to noise ratio and minimal radiation scatter. Combining these advantages with rapid Xenon saturation of the blood provides correlations of L lambda and LCBF with images of normal and abnormal brain in a safe, useful and non-invasive manner.
authors.affiliation: Cerebral Blood Flow Laboratory, Veterans Administration Medical Center, Houston, Texas.
authors.forename: J S
authors.initials: JS
authors.lastname: Meyer
authors.forename: T
authors.initials: T
authors.lastname: Shinohara
authors.forename: A
authors.initials: A
authors.lastname: Imai
authors.forename: M
authors.initials: M
authors.lastname: Kobari
authors.forename: F
authors.initials: F
authors.lastname: Sakai
authors.forename: T
authors.initials: T
authors.lastname: Hata
authors.forename: W T
authors.initials: WT
authors.lastname: Oravez
authors.forename: G M
authors.initials: GM
authors.lastname: Timpe
authors.forename: T
authors.initials: T
authors.lastname: Deville
authors.forename: E
authors.initials: E
authors.lastname: Solomon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D005260:Female; D005740:Gases; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014978:Xenon
chemical_list: D005740:Gases; D014978:Xenon