MR-guided therapy control.

<p>Example case (A) of an initially T1-hypointense recurrent tumor (arrowheads) at the margin of an older inhomogeneously hyperintense ablation zone. Phase difference image derived from subtracting a non-heating reference image (B) and thermal map with color-coded pixels in a quadrate ROI at peak temperature as being displayed on screen during the procedure (C), fast GRE sequences at 1.5 T Magnetom Avanto, Siemens Healthcare, Erlangen, Germany; TE 12 ms, TR 970 ms, BW 260 Hz/pixel, flip angle 65°, field of view (FOV) 320 mm, matrix size 128x128, slice thickness of 3 mm, fat suppression. Color-codes of phase image and online ROI are unequal. The last picture (D) shows the ablation-induced necrosis (arrowheads) demarcated as a lack of extracellular contrast uptake at portal venous phase on 24 h CEMR.