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Purpose: Radiofrequency ablation (RFA) for primary liver tumors and liver metastases is restricted by a limited ablation size. Multipolar RFA is a technical advancement of RFA, which is able to achieve larger ablations. The aim of this ex vivo study was to determine optimal ablation parameters for multipolar RFA depending on applicator distance and energy input. Methods. RFA was carried out ex vivo in porcine livers with three internally cooled, bipolar applicators in multipolar ablation mode. Three different applicator distances were used and five different energy inputs were examined. Ablation zones were sliced along the cross-sectional area at the largest ablation diameter, orthogonally to the applicators. These slices were digitally measured and analyzed. Results: Sixty RFA were carried out. A limited growth of ablation area was seen in all test series. This increase was dependent on ablation time, but not on applicator distance. A steady state between energy input and energy loss was not observed. A saturation of the minimum radius of the ablation zone was reached. Differences in ablation radius between the three test series were seen for lowest and highest energy input (P < .05). No differences were seen for medium amounts of energy (P > .05). Conclusions. The ablation parameters applicator distance and energy input can be chosen in such a way, that minor deviations of the preplanned ablation parameters have no influence on the size of the ablation area.

Background The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo. Methods Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry. Results Flow rates of 1 ml/min already caused a significant cooling effect (P < 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min. Conclusions Minimal vascular flows of >1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels.

Purpose In situ ablation is increasingly being used for the treatment of liver malignancies. The application of these techniques is limited by the lack of a precise prediction of the destruction volume. This holds especially true in anatomically difficult situations, such as metastases in the vicinity of larger liver vessels. We developed a three-dimensional (3D) planning system for laser-induced thermotherapy (LITT) of liver tumors. The aim of the study was to validate the system for calculation of the destruction volume. Methods LITT (28 W, 20 min) was performed in close contact to major hepatic vessels in six pigs. After explantation of the liver, the coagulation area was documented. The liver and its vascular structures were segmented from a pre-interventional CT scan. Therapy planning was carried out including the cooling effect of adjacent liver vessels. The lesions in vivo and the simulated lesions were compared with a morphometric analysis. Results The volume of lesions in vivo was 6,568.3 +/- 3,245.9 mm(3), which was not different to the simulation result of 6,935.2 +/- 2,538.5 mm(3) (P = 0.937). The morphometric analysis showed a sensitivity of the system of 0.896 +/- 0.093 (correct prediction of destructed tissue). The specificity was 0.858 +/- 0.090 (correct prediction of vital tissue). Conclusions A 3D computer planning system for the prediction of thermal lesions in LITT was developed. The calculation of the directional cooling effect of intrahepatic vessels is possible for the first time. The morphometric analysis showed a good correlation under clinical conditions. The pre-therapeutic calculation of the ablation zone might be a valuable tool for procedure planning.

Einleitung: Zwei Entdeckungen haben die Leistenhernienchirurgie in den letzten zwei Dekaden revolutioniert: der Einsatz alloplastischen Materials seit den 80er und die Einführung der laparoskopischen Leistenhernienchirugie in den 90er Jahren des letzten Jahrhunderts. Unter ökonomischen Zwängen[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: Die erste beschriebene intraoperative Intestinoskopie wurde 1976 durchgeführt. Seitdem hat sie sich als ein Standard in der Diagnostik und Therapie von Dünndarmläsionen etabliert. Die häufigste Indikation für die Durchführung einer intraoperativen Intestinoskopie[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: In-situ-Ablationsverfahren nehmen mittlerweile einen festen Platz in der Therapie von kolorektalen Lebermetastasen ein. Im klinischen Einsatz haben sich parallel verschiedene Ablationssysteme sowohl für die perkutane als auch für die offen-chirurgische Ablation etabliert. Dabei[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: Im Gegensatz zu der konventionellen Defäkographie ist die MR-Defäkographie noch nicht als Standardprozedur zur Darstellung von Rektozele oder Intussuszeption etabliert, bietet aber den Vorteil der fehlenden Strahlenbelastung für den Patienten. Die vorliegende Studie vergleicht[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: Bei der akuten Sigmadivertikulitis (SD) spielt die Diagnostik mittels Computertomographie (CT) im Rahmen der prätherapeutischen Stadieneinteilung und Therapieentscheidung eine wichtige Rolle. Hierdurch werden komplizierte Stadien erfasst, die als Indikation zur operativen Therapie gelten.[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: Die Behandlung der Colitis ulcerosa (CU) und der FAP durch eine Coloproktomucosektomie (CPM) gilt als etabliertes Verfahren. Neben dem standardisierten offenen Vorgehen wurden in den letzten Jahren zunehmend auch laparoskopisch assistierte Operationen für diese Patienten durchgeführt.[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: Der Einsatz der Radiofrequenzablation (RFA) in der Therapie von Lebermetastasen birgt das Risiko lokaler Rezidive aufgrund unzureichender Überlappung von Destruktionsvolumen und Tumorgeometrie, bzw. unvollständig therapierter Tumorareale entlang von Gefäßen. Als wesentlicher[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: Die Inzidenz und Prävalenz sogenannter Krankenhauskeime wie MRSA, ESBL und VRE ist kontinuierlich steigend. Konkrete Zahlen für ESBL und VRE sind nicht vorhanden jedoch liegt die Prävalenz von MRSA in Berliner Krankenhäusern bei 5%. Im benachbarten europäischen[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Einleitung: Die Coloproktomukosektmoie (CPM) mit ileopouch-analer Anastomose (IPAA) hat sich zu einem kontinenzerhaltenden Standardverfahren in der Behandlung der therapierefraktären Pancolitis ulcerosa und der familiären adenomatösen Polypose des Colon entwickelt. Die dauerhafte Rückverlagerung[for full text, please go to the a.m. URL], 126. Kongress der Deutschen Gesellschaft für Chirurgie

Objectives: Aim of the study was to evaluate the precise influence of different intrahepatic vessels, vessel sizes, and distances from the applicator on volume and shape of hepatic laser ablation zones in an in vivo porcine model. Materials and Methods: The study was approved by the institutional animal care and use committee. Eighteen computed tomography-guided Nd:YAG laser ablations were performed in the livers of 10 pigs at varying distances from hepatic veins and portal fields. After hepatectomy the livers were cut into 2-mm slices perpendicular to the laser applicator axes. For each ablation zone the maximum achievable (ideal) volume, the segmented (real) volume, the maximum radius, and the radius at the position of adjacent hepatic vessels were determined. The shapes of the ablation zones were evaluated qualitatively. Comparative statistics using the unpaired t test and a multiple linear regression analysis were performed. Results: Ideal and real ablation zone volumes differed by 27.3% (8.6 ± 1.5 mL vs. 6.4 ± 1.1 mL; P < 0.0001). Thirty-eight of 60 (63%) hepatic veins versus 28 of 31 (90%) portal veins within the central slices of the 18 ablation zones led to a reduction of the ablation zone's radius, depending on the distance between the vessel and the applicator and the vessel type. Portal fields revealed stronger effects than hepatic veins. The vessel diameter showed no independent effect (P > 0.05). When influencing, all hepatic veins showed a focal indentation whereas portal fields always showed broad flattening of the ablation zone. Conclusions: Portal fields lead to more heat sink than hepatic veins. The effects decreased with the distance between vessel and applicator tip, but less so for portal fields. The 2 vessel types induced considerably different shape alterations of the ablation zones. These results were not dependent on vessel size. This should be considered in the planning of thermal tumor ablations.