TmDOTP^5-: A substance for NMR temperature measurements in vivo

The chemical shifts of ³¹P and ¹H in thulium 1,4,7,10- tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonate) (TmDOTP^5-) are approximately two orders of magnitude more sensitive to temperature than are water proton and ¹⁹F shifts. In the physiologically relevant pH range, the ³¹P and ¹H chemical shifts of TmDOTP^5- are linear functions of temperature between 25 and 47°C. The results indicate that using Tm-DOTP^5- can provide measurements of temperature in vivo that are significantly more accurate than methods based on water and fluorocarbon chemical shifts.