Figure 4: (a): Virtual touch tissue quantification (VTQ) in a HCC residual tumor area (arrow) after RFA with a shear wave velocity of 2.82 m/s. (b): CEUS image of the same residual tumor. Left part of lesion with residual tumor (arrow) shows enhancement after contrast injection whereas contrast perfusion cannot be observed in the completely ablated area. The border between residual tumor area and complete ablation area can be displayed clearly by CEUS.