TABLE 1.
Important properties of radiopharmaceuticals used in PET myocardial perfusion imaging. The physical half-life of the parent radionuclide (15O, 82Rb, 13N, 11C, and 18F), mean positron range in water for the parent radionuclide (values are taken from11), and extraction (E) fraction formula that connects K1 calculated from kinetic modeling and myocardial blood flow (MBF). K1 = MBF·E.
| Physical half-life of radionuclide (min) | Mean positron range in water (mm) | MBF & K1 (mL min−1 g−1) (extraction formula) | |
|---|---|---|---|
| 15O-water | 2.04 | 3.0 | K1 = MBF |
| 82Rb* | 1.273 | 7.1 |
K1 = MBF·(1−e−(0.45+0.16MBF)/MBF) for 0 ≤ MBF ≤ 0.92; MBF = 3.664 + (K1 − 0.92) for MBF > 0.92 No relationship when MBF > 3.7 |
| 13N-ammonia** | 9.965 | 1.8 | K1 = MBF·E |
| 11C-acetate*** | 20.334 | 1.2 | K1 = MBF·E, or K1 = MBF·(1–0.637e−1.198/MBF) |
| 18F-flurpiridaz**** | 109.771 | 0.6 | K1 = MBF·0.94 |
There are slightly different expressions reported. The values in this table were taken from21.
E is close to 1 for 13N-ammonia. Either one-tissue compartment model or two-tissue compartment model is used to derive K1.25
E is close to 1 for 11C-acetate when the first-pass extraction data (i.e., first 2–3 minutes of dynamic data at most) are used. Using 2-tissue compartment model, a nonlinear extraction formula could be obtained as well.34
Although there is a roll-off of the linearity of the extraction fraction, the linearity is maintained at very high flow rates for 18F-flurpiridaz.12 For practical values of MBF, there is no need to correct for the nonlinearity.