On-line measurement of exhaled [11C]CO2 during PET.
The purpose of this study was to develop and evaluate a system for the continuous on-line measurement of expired 11CO2 during 11C PET studies.


METHODS
A detector system was developed that allowed continuous sampling of expired air during PET. Healthy volunteers (n = 4) underwent PET with [11C]CO2 during which expired air, tomographic tissue activity, and blood data were collected. The measured expired-air 11CO2 radioactivity time courses were filtered, and an envelope was extracted and compared with the time course of 11CO2/H11CO3 in blood.


RESULTS
Good agreement was found between the shapes of the expired-air envelope and the time course in blood, enabling quantitative calibration against discrete blood samples.


CONCLUSIONS
A system for the continuous monitoring of expired radioactivity during PET has been developed and evaluated with [11C]CO2. This monitoring enables the quantitative continuous measurement of 11CO2/H11CO3- in blood.
Gunn
R N
RN
Medical Research Council Cyclotron Unit, Hammersmith Hospital, Imperial College School of Medicine, London, United Kingdom.
Ranicar
A
A
Yap
J T
JT
Wells
P
P
Osman
S
S
Jones
T
T
Cunningham
V J
VJ
D002245:Carbon Dioxide / Q000032:analysis; D002250:Carbon Radioisotopes; D006801:Humans; D008991:Monitoring, Physiologic / Q000379:methods; D012588:Scintillation Counting; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D002245:Carbon Dioxide