Measurement of 18F-FDG concentrations in blood samples: comparison of direct calibration and standard solution methods.
OBJECTIVE
The purpose of this study was to compare the accuracy and reliability of 2 well counter methods for measuring the activity concentration of (18)F-FDG in blood samples.


METHODS
Three to 5 blood samples from 154 patient studies were weighed and measured in a well counter. The (18)F-FDG activity concentration was derived using, first, a direct calibration factor to convert measured well counter readings into activity concentration and, second, a comparison of measured counts with those of a specified standard solution.


RESULTS
The ratio between the activity concentration results of the 2 methods was 0.996 +/- 0.033, indicating that the methods provided equal results.


CONCLUSIONS
Because the standard solution method is more prone to human error, less reproducible, and more labor intensive, preference should be given to the direct calibration method.
Greuter
Henri N J M
HN
PET Center, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands. HNJM.Greuter@VUmc.NL
Boellaard
Ronald
R
van Lingen
Arthur
A
Franssen
Eric J F
EJ
Lammertsma
Adriaan A
AA
D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards; D002138:Calibration; D019788:Fluorodeoxyglucose F18 / Q000097:blood* / Q000493:pharmacokinetics*; D006801:Humans; D011865:Radioisotope Dilution Technique / Q000295:instrumentation*; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D019275:Radiopharmaceuticals / Q000097:blood / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18