Figure 10.

MR-measured temperature at the focus of the transducer over the course of the treatment (a) and comparison of measurement and calculation in the pre-boiling part of the curve (b). MRI generally tracked the heating during and the cooling following HIFU. However, because of the presence of boiling bubbles during HIFU exposure from 7 to 20 s, temperature readings were erratic. Immediately before boiling (7 s), the calculated peak temperature was 100 °C. The temperature measured with MRI in the focal voxel and the calculated temperature averaged over the voxel volume was only 73 °C.