Physical and Biologic Comparisons of Myocardial Perfusion Imaging Agents
| Factor | 99mTc-Sestamibi or 99mTc-tetrofosmin | 201Tl |
|---|---|---|
| Extraction fraction | Lower | Higher |
| Myocardial retention | Prolonged | Comparatively shorter |
| Myocardial washout | Slower | Rapid |
| Redistribution | Minimal | Significant |
| Myocardial perfusion at high blood flow | Same | Same |
| Injected dose | Higher | Lower |
| Counting statistics | Better | Fair |
| Physical half-life | 6 h | 73.1 h |
| Photon energy | 140 kEv | 68–80 kEv (abundance), 170 kEv (∼10%), and 135 kEv (∼3%) |
| Radiation dosimetry | More favorable | Less favorable |