Table 2.

Comparison of pre-clinical cell tracking methods, data adapted and modified from,^{5, 61,62} we noted that Ultrasound and CT are not well characterized for tracking cells

Modality	Resolution	Acquisition speed	Sensitivity/cells detected	Cell labeling agents
Optical	20 µm/poor at depth	<Seconds	μM/1000	Reporter gene/dyes (IcG, Cy, Luciferase)
Nuclear medicine	1000–2000 µm	Minutes	pM/10,000–100,000	Radionuclide (In111, Tc99m, 18F, 68Ga)
MRI	25–500 µm	Minutes	mM/10,000	Contrast agent (Gd, Mn, SPIO, 19F)
MPI	250–1400 µm	Minutes	0.1 µM/10– 200	SPIO

MPI, magnetic particle imaging; SPIO, superparamagnetic iron oxide nanoparticle.