Temperature monitoring of internal body heating induced by decoupling pulses in animal C-13-MRS experiments

A temperature monitoring method to promote safety with regard to tissue hea ting induced by RF irradiation during MRI procedures, especially carbon-13 magnetic resonance spectroscopy (C-13-MRS), is proposed. The method is base d on the temperature dependence of the water proton chemical shift (-0.01 p pm/degrees C) combined with phase mapping. Using this method, temperature c hanges were measured in rats (n = 4) employing practical H-1-decoupled C-13 -MRS pulse sequences for 1D projections (TR = 1000 ms, acquisition time = 1 5 ms, matrix = 256, spatial resolution = 0.2 mm) and 2D images (TR = 1500 m s, acquisition time = 840 ms, matrix = 128 x 32, spatial resolution = 0.8 x 1.5 mm). Measurement error was 0.18 degrees C (SD) for 1D acquisition and 0.39 degrees C (SD) for 2D acquisition, demonstrating the feasibility of th is temperature mapping method. Further studies should be conducted in human subjects to monitor patient safety and to optimize the pulse sequences emp loyed. Magn Reson Med 43:796-803, 2000. (C) 2000 Wiley-Liss, Inc.