Table 2:

MR imaging contrast

MR Imaging Contrast Agent	Examples	Predominant Effect	MR Imaging Sensitivity	Notes
T1 agent	Gd-DTPA (magnevist), Gd-DOTA (dotarem), Mn²⁺	T1	++	Gd is chelated for toxicity reasons
T2 agent	SPIO, USPIO, MION, CLIO	T2	++++	Large range of sizes
CEST, PARACEST	Amino acids, sugars; Eu-DOTA	Saturation transfer	++	Preclinical stage
Heteronuclei	¹⁹F, ³¹P	Hot spot imaging	+	Negligible background signal

Note:—Plus signs indicate the relative sensitivity of the different contrast mechanisms.