Variability in plasma tracer and metabolite levels
| Time (min) . | 2-[11C]Thymidine . | . | 11CO2 . | . | . | |||
|---|---|---|---|---|---|---|---|---|
| . | Mean ± SD* (%) . | COV† (%) . | Mean ± SD* (%) . | COV† (%) . | COV‡ (%) . | |||
| 1.50 | 90.1 ± 3.4 | 4 | 2.7 ± 5.0 | 186 | 37§ | |||
| 2.50 | 62.8 ± 9.0 | 14 | 24.7 ± 14.2 | 57 | 11 | |||
| 3.50 | 32.5 ± 9.2 | 28 | 46.2 ± 12.7 | 27 | 2 | |||
| 5.25 | 13.9 ± 5.1 | 37 | 56.9 ± 13.0 | 23 | 1 | |||
| 7.75 | 7.8 ± 2.5 | 32 | 63.1 ± 13.7 | 22 | 2 | |||
| 15.25 | 5.1 ± 2.2 | 44 | 67.7 ± 13.7 | 20 | 2 | |||
| Time (min) . | 2-[11C]Thymidine . | . | 11CO2 . | . | . | |||
|---|---|---|---|---|---|---|---|---|
| . | Mean ± SD* (%) . | COV† (%) . | Mean ± SD* (%) . | COV† (%) . | COV‡ (%) . | |||
| 1.50 | 90.1 ± 3.4 | 4 | 2.7 ± 5.0 | 186 | 37§ | |||
| 2.50 | 62.8 ± 9.0 | 14 | 24.7 ± 14.2 | 57 | 11 | |||
| 3.50 | 32.5 ± 9.2 | 28 | 46.2 ± 12.7 | 27 | 2 | |||
| 5.25 | 13.9 ± 5.1 | 37 | 56.9 ± 13.0 | 23 | 1 | |||
| 7.75 | 7.8 ± 2.5 | 32 | 63.1 ± 13.7 | 22 | 2 | |||
| 15.25 | 5.1 ± 2.2 | 44 | 67.7 ± 13.7 | 20 | 2 | |||
Values are percentages of the total plasma activity and are the mean and SD of data from 39 patients.
Interpatient COV.
Intrapatient COV was determined in four patients by taking three repeat estimates of plasma 11CO2 during the same scanning session. The values are the mean COV for the four patients.
Data for two patients only; for the remaining two patients, counts were too low to obtain reliable repeat estimates.