Chest wall temperature during radiofrequency ablation in a normal rabbit lung model

Abstract

The aim of this study was to examine the actual temperature during lung radiofrequency ablation (RFA) and pathological changes due to thermal damage in the pleural tissue of the chest wall in a rabbit model. The study was conducted on 14 Japanese white rabbits with normal lungs. Under computed tomography guidance, the electrode with a 2-cm expandable tip was inserted into the lower lung lobe and positioned so the tip of the needle touched the thoracic wall upon expansion. A thermometer was inserted 5 mm lateral to the point of electrode insertion. RFA was applied at 30 W (n = 7) or 15 W (n = 7) until maximum impedance (i.e., roll-off) or for 4 min at the longest. Local tissue temperature was recorded. The chest wall was dissected out immediately after RFA for histological examination. The mean (+/- SD) maximum tissue temperature at 30 W (86.7 degrees +/- 10.0 degrees C) was not significantly different from that at 15 W (82.1 degrees +/- 6.2 degrees C). The mean ablation time to increase tissue temperature to 50 degrees , 60 degrees , and 70 degrees C was faster at 30 W (13, 27, and 49 s, respectively) than at 15 W (13, 56, and 115 s, respectively) (P < 0.05). Histological examination showed pleural sloughing at the point of needle insertion and ring-shaped thermal injury in the chest wall. With rabbit lung RFA near the chest wall, ablation immediately below the pleura resulted in a rise of local tissue temperature to >80 degrees C and thermal injury.