**2.5 Cell sequestration**

Potentially saturable mechanism that is mostly associated with spleen and refers to the process where damaged and old RBC's removed from circulation [29]. It is unlikely for the relatively small numbers of cells used for imaging. The radiopharmaceutical preparation is carried out by in vitro labeling of red blood cells with technetium-99 m using modified Brookhaven labeling method and then damaging them by heating at 49°C for fifteen minutes (**Figure 5**).
