. Author manuscript; available in PMC: 2012 Jan 1.

Published in final edited form as: Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2011 Jan-Feb;3(1):86–99. doi: 10.1002/wnan.115

TABLE 2.

Comparison of ⁹⁹Tc-Annexin and the AnxCLIO-Cy5.5 Nanoparticle for In Vivo Imaging

	⁹⁹Tc-Annexin	AnxCLIO-Cy5.5
Blood half-life	Minutes	2–3 h¹⁵
Extravascular biodistribution	Yes	Yes^14–16
Metabolism	Renal elimination	Degradation by macrophages/RES
Sensitivity to low levels of apoptosis	Yes¹¹	Yes¹⁶
Distinction of apoptosis and necrosis	Yes¹³	Yes^15,16
Spatial resolution	Poor	Excellent^14–16
Background signal in blood and adjacent organs	Highly problematic (major impact on signal in ROI)	Not problematic,^14–16 (no impact on signal in ROI)
Microscopy/histology of agent	No	Yes^15,16
Integration with functional data	Not routine	Routine/excellent^14–16
Nonspecific uptake by inflammatory cells (lymphocytes, macrophages)	Yes, likely some loss of specificity	Loss of specificity due to macrophage uptake
Competition from tissue and blood pools of endogenous annexin^48–51	Yes (trace amounts of annexin injected)	No (non-trace amounts of annexin injected)
Interval required for serial imaging	Short	Unknown (likely longer)

RES, reticuloendothelial system; ROI, region-of-interest.