Table 3.

Summary of imaging methods used for detection of tumors in living mice.

Method	Physical basis	Reagents used	Spatial resolution	Reporter gene needed	Smallest detectable tumor (diameter)	Analysis time	Main advantages	Main disadvantages
T2W-MRI	Proton spin relaxation after radiowave emission	None	100 μm	No	1 mm	3 hours/ mouse 30 hours/10 mice	High spatial resolution; Anatomical information; Gives tumor localization, size and morphology	Low throughput; Respiratory motion and high background make tumor detection in lungs challenging
FDG-PET	High-energy γ rays	18Fluoro-deoxy-glucose	2 mm	No	<1 mm	3 hours/ mouse 13 hours/ 10 mice	Detection of nonpalpable tumors; Quantifies tumor cell metabolism; Gives tumor localization	High background in some organs (brain, and bladder) prevents tumor detection in these regions
Biolumines-cence imaging	Visible light emitted during chemical reaction	D-luciferin substrate	1 to 10 mm dependant on tissue depth	Yes	<1 mm	1 hour/ mouse 2 hours/10 mice	Detection of nonpalpable tumors; Low background; Relative measure of tumor size; High throughput	Light emission dependant on 1/ tissue depth, 2/local availability of substrate reagents (luciferin, O2, and ATP)
Fluorescence imaging	Visible light emitted after fluorochrome excitation	None	1 to 10 mm dependant on tissue depth	Yes	2 mm	30 min/ mouse 1 hour/ 10 mice	High throughput	Light emission dependant on tissue depth; High background due to tissue autofluorescence