A noninvasive magnetic resonance temperature imaging technique for fat-water mixed tissues was proposed. This technique uses the temperature dependence of the spin-lattice relaxation time (
T1) of protons originated from methylene chain (CH
2) of fat as well as the resonance frequency shift of water proton (H
2O). A multiple point Dixon method in conjunction with a multiple flip angle method enables simultaneous calculation of
T1 of CH
2 and the resonance frequency change of H
2O. A phantom with two mayonnaise tubes, one heated by microwave while the other kept at room temperature was imaged at 3 Tesla during the cooling process by a spoiled gradient recalled acquisition in steady state (SPGR) of the following conditions ; field of view, 32×32 cm
2 ; matrix, 64×64 ; parallel imaging factor, 2 ; repetition time, 36 ms ; echo time spacing, 1.15 ms ; and flip angles, 20, 50 and 70 degrees. Signals obtained with each flip angle were processed by IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation) algorithm to obtain H
2O, CH
2 and CH
3 images. The smaller components of fat were ignored for simplicity. Temperature distribution of fat in the phantom was imaged by
T1 of CH
2 obtained from the three CH
2 images with different flip angles, while that of water with the change in the phase difference between H
2O and CH
2 or the relative phase change in H
2O. Those temperature images were then fused as a weighted sum of H
2O and CH
2 fractions in each voxel. The resultant images highly correlated with the probe-measured temperature elevation demonstrating that simultaneous fat-water temperature imaging is feasible and is expected to be sufficient for clinical practice.
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