NONINVASIVE TEMPERATURE-MEASUREMENT IN-VIVO USING A TEMPERATURE-SENSITIVE LANTHANIDE COMPLEX AND H-1 MAGNETIC-RESONANCE SPECTROSCOPY

A new lanthanide complex, praseodymium-2-methoxyethyl-DO3A, was tested as a temperature indicator for H-1 magnetic resonance spectroscopy un der in vivo conditions, using a 2-T imaging system. The chemical shift of the methoxy group of the compound is strongly temperature dependen t. In vitro, a shift change of -0.131 ppm/degrees C was found. The sig nal was shifted by about -24 ppm relative to the water signal, allowin g easy water suppression and signal identification in vivo. The body t emperatures of eight anesthetized rats were measured in the liver afte r intravenous administration of 1 mmol/kg of the praseodymium complex under different heating conditions of the animal. The temperatures cal culated from the spectra were in good agreement (deviation < +/- 1 deg rees C) with values obtained simultaneously with a thermocouple placed in the rectum of the animals.