Liat Appelbaum MD, Presenter: Nothing to Disclose

Eli Ben David, Abstract Co-Author: Nothing to Disclose

Jacob Sosna MD, Abstract Co-Author: Consultant, ActiViews Ltd Research grant, Koninklijke Philips Electronics NV

Isaac Nissenbaum BSc, Abstract Co-Author: Nothing to Disclose

S. Nahum Goldberg MD, Abstract Co-Author: Consultant, AngioDynamics, Inc, Fremont, CA Research support, AngioDynamics, Inc, Fremont, CA

To prospectively characterize and optimize IRE ablation in order to determine the best parameters to achieve the largest target zones of coagulation.

IRE ablation (n = 110) was performed in-vivo in 21 pig livers using two 18g electroporation electrodes placed under US guidance and a Nanoknife generator (Angiodynamics, Fremont, CA). Five variables for energy deposition and electrode configuration were sequentially studied including: a) number of IRE electrical pulses (20, 50, 70, 90, 100); b) length of pulse repetitions (20, 50, 70, 90, 100 µsec); c) generator voltage (2250, 2,650, and 3000 V); d) spacing between electrodes (1.5, 2, 2.5 cm); and e) the length of electrode exposure (1.0, 1.5, 2, 2.5, and 3.0 cm). Zones of ablation were determined at gross and histopathology 2–3hr post-IRE. Dimensions of ablation were compared and subject to statistical analysis.

For the 1.5 cm spacing and 2 cm electrode exposure at 2,250V, there was no statistical difference in the size of ablation when varying the number or length of pulses from 50 - 100, with each parameter combination yielding 2.9±0.2 x 1.6±0.2 x 2.4±0.9 cm (width, depth, height, respectively). Yet, increasing pulse width or number over 70 caused increased audible popping, hyperechogenicity/gas, and frank coagulation around the electrode. Increasing the voltage (from 2,250 to 3,000V) for 70 pulse repetitions of 70 µsecs increased the ablation cross-sectional dimensions to 3.2±0.2 x 2.0±0.2 cm (p<0.003). Greater width of ablation (3.9±0.5 cm; p< 0.01), was achieved at 2cm electrode spacing (with similar depth [1.9±0.3 cm]); however, most consistent results required 90 repetitions of 100 µsec pulses. 2.5cm spacing resulted in bilobed or two separate zones of ablation. Whereas electrode exposure length did not influence width or depth, a linear correlation (r2=0.65) was noted for height which ranged from 2.3±0.3 to 5.2±1.0 cm (1-3cm exposures, respectively).

Predictable zones of tissue destruction can be achieved for IRE. Ablation dimensions are sensitive to multiple parameters suggesting that precise technique and attention to detail will be particularly important when using this modality.

Characterization and optimization of IRE parameters will enable the best algorithms to be developed for clinical tumor ablation with this modality. 

Appelbaum, L, Ben David, E, Sosna, J, Nissenbaum, I, Goldberg, S, Characterization and Optimization of Irreversible Electroporation (IRE) Ablation in in Vivo Porcine Liver.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9009936.html