2-[11C]thymidine positron emission tomography reproducibility in humans.
OBJECTIVE
To evaluate the reproducibility of 2-[11C]thymidine positron emission tomography (PET) scanning in patients with advanced intra-abdominal malignancies.


METHODS
The reproducibility of 2-[11C]thymidine PET was studied by comparing interpatient and intrapatient variability (coefficient of variability, COV) of both blood and tissue data. Arterial plasma metabolite levels were measured using on-line sampling and high-pressure liquid chromatography. 2-[11C]Thymidine retention in tissue was measured as the standardized uptake value at the end of the scan (SUV(end)), the area under the time-activity curve (AUC(0-1 hour)), and the fractional retention of thymidine (FRT). A group of seven patients were scanned 1 week apart with no intervening anticancer therapy.


RESULTS
There was interpatient variability in the levels of 2-[11C]thymidine and its main metabolite, 11CO2, in plasma. Variability in 2-[11C]thymidine PET data was greater between (COV: SUV(end) = 38%, AUC(0-1 hour) = 32%, FRT = 47%) than within (COV: SUV(end) = 8%, AUC(0-1 hour) = 2%, FRT = 9%) patients. There was a borderline significant difference between the paired tumor data for SUV(end) (P = 0.041), but not for AUC(0-1 hour) (P = 0.81) or FRT (P = 0.90). There was a good correlation between paired data for SUV(end) (r = 0.98), AUC(0-1 hour) (r = 0.99), and FRT (r = 0.95).


CONCLUSIONS
This is the first report showing that 2-[11C]thymidine PET scanning is reproducible in humans. Repeat scanning of tumor proliferation using 2-[11C]thymidine PET is feasible to perform in human intra-abdominal malignancies and should aid the future rapid assessment of antiproliferative tumor agents.
Wells
Paula
P
Department of Cancer Medicine, Imperial College London, Hammersmith Hospital, London, United Kingdom.
Gunn
Roger N
RN
Steel
Colin
C
Ranicar
Alex S
AS
Brady
Frank
F
Osman
Safiye
S
Jones
Terry
T
Price
Pat
P
D000008:Abdominal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D002250:Carbon Radioisotopes; D005260:Female; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D013154:Spleen / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism* / Q000493:pharmacokinetics; D013997:Time Factors; D014018:Tissue Distribution
D002250:Carbon Radioisotopes; D013936:Thymidine