HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Frericks, B. B. Articles by Albrecht, T. Search for Related Content PubMed PubMed Citation Articles by Frericks, B. B. Articles by Albrecht, T.

Multipolar Radiofrequency Ablation of Hepatic Tumors: Initial Experience¹

¹ From the Department of Radiology and Nuclear Medicine (B.B.F., K.J.W., T.A.) and Department of Surgery (J.P.R.), Campus Benjamin Franklin-Charité-University Medicine Berlin, Hindenburgdamm 30, 12200 Berlin, Germany; and Celon Medical Instruments, Teltow, Germany (A.R.). Received June 23, 2004; revision requested September 1; revision received January 14, 2005; accepted February 16. Address correspondence to B.B.F. (e-mail: bernd.frericks{at}charite.de).

View larger version (20K): [in a new window]   Figure 1. Diagram shows development of ablation zone. 1, At the beginning of ablation, the tissue between the two electrodes (dark gray areas) closely around the ablation probe is coagulated (gray areas) as the current seeks to run the shortest way between the two electrodes. 2–4, With increasing time, the ablation zone grows larger. In addition, a zone of dehydration (white areas) occurs closely around the ablation probe, starting between the two electrodes and growing peripherally (arrows). The increasing zone of dehydration results in increasing tissue resistance. Once the dehydration extends along the electrodes completely, the coagulation process has ended and power output is stopped automatically.

View larger version (17K): [in a new window]   Figure 2. Graph shows ablation zone volume according to the number of probes used. Only those 14 ablation zones that were achieved without the Pringle maneuver and did not fuse with previous ablation zones (12 with the percutaneous approach and two with the intraoperative approach) were included in this analysis to eliminate effects other than those caused by the multipolar RF ablation device. The size of the ablation zone increased with the number of probes used. n = number of ablation zones. Error bars indicate minimum and maximum values.

View larger version (14K): [in a new window]   Figure 3. Graph shows relationship between the volume of the ablation zone and applied energy. Only those 14 ablation zones that were achieved without the Pringle maneuver and did not fuse with previous ablation zones (12 with the percutaneous approach and two with the intraoperative approach) were included in this analysis to eliminate effects other than those caused by the multipolar RF ablation device. Eleven ablation zones showed an increase in size with an increase in applied energy (R2 = 0.8816), as determined with the following equation: V = (0.496 x AE) + 1.8611, where V is volume in milliliters and AE is applied energy in kilojoules. Three ablation zones (gray squares) were smaller than expected on the basis of the applied energy: In the first percutaneously treated patient, some of the energy was applied to the abdominal wall. In another percutaneously treated patient, the newly created ablation zone lay directly below an older ablation zone from a previously performed interstitial laser ablation; therefore, some of the energy might have been applied to the previous laser ablation zone. A third ablation zone created intraoperatively without the Pringle maneuver lay immediately between the inferior vena cava and the right portal vein.

View larger version (90K): [in a new window]   Figure 4a. Images illustrate ablation zone (arrow) shapes. Examples are shown for (a) a concentric ablation zone (achieved with three probes; total energy deposited, 81.4 kJ; achieved volume, 58 mL), (b) a moderately eccentric ablation zone (achieved with three probes; total energy deposited, 133.1 kJ; achieved volume, 69 mL) whose shape was secondary to perfusion effects from adjacent vessels, and (c) a severely eccentric ablation zone (achieved with two probes; total energy deposited, 60.5 kJ; achieved volume, 20 mL) whose shape was secondary to partial fusion of single ablation zones. Images on the left are the result of semiautomatic segmentation and visualization of the ablation zone on the basis of the portal venous phase images obtained at initial contrast-enhanced MR imaging. Images on the right are representative portal venous phase images from initial contrast-enhanced MR imaging (three-dimensional volumetric interpolated body examination; 5.2/2.6; flip angle, 20°) performed 24–48 hours after RF ablation.

View larger version (96K): [in a new window]   Figure 4b. Images illustrate ablation zone (arrow) shapes. Examples are shown for (a) a concentric ablation zone (achieved with three probes; total energy deposited, 81.4 kJ; achieved volume, 58 mL), (b) a moderately eccentric ablation zone (achieved with three probes; total energy deposited, 133.1 kJ; achieved volume, 69 mL) whose shape was secondary to perfusion effects from adjacent vessels, and (c) a severely eccentric ablation zone (achieved with two probes; total energy deposited, 60.5 kJ; achieved volume, 20 mL) whose shape was secondary to partial fusion of single ablation zones. Images on the left are the result of semiautomatic segmentation and visualization of the ablation zone on the basis of the portal venous phase images obtained at initial contrast-enhanced MR imaging. Images on the right are representative portal venous phase images from initial contrast-enhanced MR imaging (three-dimensional volumetric interpolated body examination; 5.2/2.6; flip angle, 20°) performed 24–48 hours after RF ablation.

View larger version (88K): [in a new window]   Figure 4c. Images illustrate ablation zone (arrow) shapes. Examples are shown for (a) a concentric ablation zone (achieved with three probes; total energy deposited, 81.4 kJ; achieved volume, 58 mL), (b) a moderately eccentric ablation zone (achieved with three probes; total energy deposited, 133.1 kJ; achieved volume, 69 mL) whose shape was secondary to perfusion effects from adjacent vessels, and (c) a severely eccentric ablation zone (achieved with two probes; total energy deposited, 60.5 kJ; achieved volume, 20 mL) whose shape was secondary to partial fusion of single ablation zones. Images on the left are the result of semiautomatic segmentation and visualization of the ablation zone on the basis of the portal venous phase images obtained at initial contrast-enhanced MR imaging. Images on the right are representative portal venous phase images from initial contrast-enhanced MR imaging (three-dimensional volumetric interpolated body examination; 5.2/2.6; flip angle, 20°) performed 24–48 hours after RF ablation.