Parmacokinetics of Technetium Radiopharmaceuticals for Brain Perfusion SPECT
| Parameter | 99mTc-HMPAO | 99mTc-ECD |
|---|---|---|
| Peak brain activity | 2 min | 2 min |
| Brain uptake (% injected dose) | 2%–3% | 4%–7% |
| Brain washout | 12%–15% over 15 min | 12%–14% the first hour; then 6%/h |
| Excretion (% at 48 h pi) | 50% liver–gut | 15% liver–gut |
| 40% kidneys | 75% kidneys | |
| Target organs | Lachrymal glands | Urinary bladder |
| Gallbladder wall | Gallbladder wall | |
| Gray-matter–to–white- matter ratio | 2–3:1 | 4:1 |
| Imaging time | Up to 4 h pi | Up to 2 h pi |
pi = postinjection.