Prediction of the ablated area prior to radiofrequency ablation for liver tumor under CT guidance.

Purpose: To evaluate the usefulness of a method we developed to predict the ablation area at the time of CT guided radiofrequency (RF) ablation for liver tumors on a CT workstation.
Material and Methods: Ten tumors (mean diameter 15.5 mm, range, 9.0-21.5 mm) in seven patients with hepatocellular carcinoma for which CT guided RF ablation was performed were subjects of this study. After advancing the electrode, plain CT was obtained. Then a simulated ball to predict the ablated area was created on the workstation. After confirming that the tumor was sufficiently within the ball, ablation was performed. The distance of the edge of the actual ablated area from that of the predicted ablated area was measured at six points in three cross-sectional directions on CT images after ablation.
Results: The procedures were successfully performed without complications. No local recurrence occurred. Mean absolute value of the distance of the gap between the actual and predicted ablated areas was 3.06 ± 2.18 mm (range: 0 to 9 mm). At 29 (55.8%) points, the actual ablated area was smaller than the predicted ablated area; it was larger in 17 (32.7%), and was the same in 6 (11.5%) points.
Conclusion: Our method produces an acceptable simulation during RF ablation under CT guidance.