2002 Volume 20 Pages 27-33
Temperature changes in both an agar phantom and beef liver during microwave ablation for 10 minutes were consecutively monitored by MR temperature mapping using the proton resonance frequency method. Three kinds of MR-compatible needle-type electrodes (A : normal type with 2 mm gap, B : high output type with 6 mm gap, C : ball-tip type with 2 mm gap) and 2 output powers (80W and 110W) were used. Maximum temperature increases were obtained with electrode A at 110W in an agar phantom, but with electrode B at 110W in beef liver. This difference might have been caused by the condition of the water molecules around the electrode. The area with a temperature increase of more than 30°C showed good correspondence with the coagulated liver. This technique, which did not require cutting the sample and could continuously detect the temperature increase in the same sample, should be useful for the evaluation of electrodes and for the optimization of output power and duration in microwave ablation.
