Accuracy of a method using short inhalation of (15)O-O(2) for measuring cerebral oxygen extraction fraction with PET in healthy humans.
PET with short inhalation of (15)O-O(2) provides regional oxygen extraction fraction (OEF) in a shorter acquisition time and with less radiation exposure than does the steady-state method. The purpose of this study was to test the accuracy of the short-inhalation technique for estimating OEF in healthy human volunteers.


METHODS
The final study population included 16 healthy volunteers, who underwent a series of dynamic PET scans consisting of short inhalation of (15)O-CO, short inhalation of (15)O-O(2), and a bolus infusion of (15)O-H(2)O to generate parametric images for cerebral blood volume (CBV), cerebral blood flow (CBF), OEF, and metabolic rate of oxygen (CMRO(2)). About 45 min before PET emission scanning, arterial and jugular blood was sampled through a catheter inserted in a radial artery and the right jugular bulb, respectively. PET-derived OEF (OEFpet) of the whole brain was compared with OEF calculated from the arteriovenous blood-sampling technique (OEFav).


RESULTS
Whole-brain-averaged CBF (mean +/- SD) measured with PET was 0.40 +/- 0.06 (range, 0.30-0.55) mL/g/min, CBV was 0.05 +/- 0.01 (range, 0.04-0.09) mL/g, CMRO(2) was 2.85 +/- 0.39 (range, 2.35-3.84) mL/100 g/min, and OEFpet was 0.39 +/- 0.06 (range, 0.30-0.51). OEFpet showed a slightly higher value than did OEFav (0.36 +/- 0.05 [range, 0.29-0.46]), but the difference was not significant. The difference in the 2 measurements (OEFpet - OEFav) did not correlate with CBF (r = -0.16; P = not statistically significant [NS]), CBV (r = -0.20; P = NS), CMRO(2) (r = -0.16; P = NS), partial arterial oxygen pressure (r = 0.29; P = NS) or partial arterial carbon dioxide pressure (r = -0.17; P = NS).


CONCLUSIONS
Compared with the arteriovenous blood-sampling technique, a technique using short inhalation of (15)O-O(2) did not significantly over- or underestimate global OEF in healthy human volunteers. The PET technique reasonably estimated the cerebral OEF in local brain tissues of healthy human volunteers.
Hattori
Naoya
N
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. nhattori@mednet.ucla.edu
Bergsneider
Marvin
M
Wu
Hsiao-Ming
HM
Glenn
Thomas C
TC
Vespa
Paul M
PM
Hovda
David A
DA
Phelps
Michael E
ME
Huang
Sung-Cheng
SC
D000328:Adult; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D010100:Oxygen; D010101:Oxygen Consumption / Q000502:physiology*; D010104:Oxygen Radioisotopes; D015203:Reproducibility of Results; D014055:Tomography, Emission-Computed; D014867:Water
D010104:Oxygen Radioisotopes; D014867:Water; D010100:Oxygen