Fast lipid-suppressed MR temperature mapping with echo-shifted gradient-echo imaging and spectral-spatial excitation

The water proton resonance frequency (PRF) is temperature dependent and can thus be used for magnetic resonance (MR) thermometry. Since lipid proton r esonance frequencies do not depend on temperature, fat suppression is essen tial for PRF-based temperature mapping. The efficacy of echo-shifted (TE > TR) gradient-echo imaging with spectral-spatial excitation is demonstrated, resulting in accurate and rapid, lipid-suppressed, MR thermometry. The met hod was validated on phantoms, fatty duck liver, and rat thigh, demonstrati ng improvements in both the speed and precision of temperature mapping. Hea ting of a rat thigh with focused ultrasound was monitored in vivo with an a ccuracy of 0.37 degrees C and a time resolution of 438 msec. Magn Reson Med 42:53-59, 1999. (C) 1999 Wiley-Liss, Inc.