a`<h h0 @@@ @@@@f._J=Xhh@ EN DB hP     & . 67}X ]cgm~ /F MU  "  W?-G!R9Percutaneous radiofrequency interstitial thermal ablation of small hepatocellular carcinoma@9Allgaier,H.P. Deibert,P. Zuber,I. Olschewski,M. Blum,H.E.l 1999 5/15/1999 Aged Carcinoma,Hepatocellular Catheter Ablation Human Liver Neoplasms methods radiography therapy Tomography,X-Ray Computed Treatment OutcomeaUI - 99266824 LA - eng PT - Letter DA - 19990610 IS - 0140-6736 SB - AIM SB - IM CY - ENGLAND JC - L0S RefMgr field[1]: Journal RefMgr field[8]: Not in File 1676-1677l Lancet 353n 91650*12 patients. RITA Model 30, No recurrences PDF ,126 PM:10335793rD> Aass19981 Aass19988+ Abe1993 Ahmed2001 Amlie1998 Amlie1998Anfinsen1998Anfinsen1998 Arata2001< Arata20017Aribandi2001 Armillotta1998 Baert1997 Baert2000" Baert2000 Bartolozzi1998 Bizzini1997# Bloom1996 Boaz1999a Boll19991 Brock1992 Brock1996* Brown2000Browning19922( Buczkowski1998 Burdio1999: Burdio1999:2 Burdio2002& Buscarini1990 Buscarini1995 Buscarini19955 Cao2002 Carrai19989 Castiella1999 Cavanna1995 Cavina19989 Chang19937 Chintapalli20017 Chopra200105 Choy2002h Christensen1997 Cicorelli1998 Cioni1998 Clark2001< Clark2001 Clouse19999- Clouse20000 Conrad19989 Conte1998 Corless1999 Cosman1988: Cosman19989Cromeens1997 Curley1997:Davidson1997 Dawson19955 Dawson19955 De1997k De20002 de Baere2001 De Gregorio1999 Denys2001Di Stasi19957 Dodd2001 Donati19988+ Enjoji199392 etal20020F1997 Fleming1997* Fleming2000) Fleming2001Foerster19989Foerster19989 Fogle1998& Fornari19907 Frank2001 Fujino20010 Garbagnati1995 Gazelle1995 Gazelle1995 Gazelle1996 Gazelle1996 Gazelle1997 Gazelle1998 Gazelle1999 Gazelle2000- Gazelle2000. Gazelle2000 Gazelle2001, Gazelle2001 Goldberg1995 Goldberg1995 Goldberg1996Goldberg1996Goldberg1997Goldberg1998Goldberg1999Goldberg1999Goldberg2000-Goldberg2000.Goldberg2000 Goldberg2001,Goldberg2001:Goldberg2001 Goletti1998 GS1997 Gu19921 Gu1996 Guemes1999:/ Haemmerich20013 Haemmerich20016 Haemmerich20014 Haemmerich20025 Haemmerich2002 Hahn19981 Halpern1996 Halpern2000. Halpern2000 Halpern2001 Hansen1999 Hashimoto2001 Hoey1996 Hoey19979Horigome20018Horigome2001;Horigome2001 Huertas2001, Huertas2001: Huertas2001 Hulbert1996) Huth20010+ Ikeda1993 Itoh200108 Itoh20011; Itoh20011 Izzo19979 Jacobs1999a, Jacobs20011Jesserun19966) Jeyarajah2001 Joh2001 Johns20013 Johnson2001 Jones1996* Jones2000) Jones2001 Kanematsu2001 Kardache2001 Kato20012 Kongsgaard1998  Kongsgaard1998  Kruskal1999- Kruskal2000 Kruskal2001, Kruskal2001: Kruskal2001L1997 Lassau200109 Lassman2002 Lazzaroni1997 Lee1996/ Lee20013 Lee20016 Lee20014 Lee2002Lencioni1998  Lenkinski2001 Leveillee1996 Lewin1999*Lindberg2000)Lindberg2001Livraghi1997Livraghi19999 Lorentzen1996 Lorentzen1996 Lorentzen1997 Lozano19999 Lu2002M1997/ Mahvi20013 Mahvi20016 Mahvi20014 Mahvi2002 Makachinas1988 Marchal1997 Marchal2000! Marchal2000" Marchal2000 McGahan1992 McGahan1996 Meloni19979 Menu20012 Merkle1999 MG1997 Miao1997  Miao2000! Miao2000" Miao2000 Monti1997 Moretti1998 Mueller1995 Mueller1995 Mueller1996 Mueller1996 Mulier19966 Mulier1997 Mulier1997 Mulier2000" Mulier2000Murasaki2001( Nagy19988 Nakao2001; Nakao2001 Nashold1988 Ni19979 Ni20000! Ni20000" Ni2000+Ninomiya1993 Nisenbaum2001< Nisenbaum2001 Nolsle1997 Nomura200108 Nomura20010; Nomura20010#O'Connor1996 Ohara2001- Oliver20000 Oliver20011: Oliver20011$ Organ1976( Owen1998 Paolicchi1998 Parker19939& Pathies1990( Patterson1998 Pellicano1997 Penninckx1997  Penninckx2000 PS1997Quaretti199559 Raman2002* Rege20000) Rege20010% RF1997 Ricci1998 Rittman1988 Rittman1995 Rittman1995 Rittman1996 Rittman1996 Roche2001 Rogers1999  Rosenthal1995  Rosenthal1995  Rosenthal1996& Rossi1990 Rossi1995S1997, Saldinger2001 Saso20010 Saxon19939 Sayre2002 Schneider1992* Scott2000) Scott2001( Scudamore1998Shankaranarayanan1999 Sheiman1999 Siperstien1999 SN1997Solbiati1996Solbiati19977Solbiati1998Solbiati2000.Solbiati2000 Soulen20010< Soulen20010 Squassante1995/ Staelin20016 Staelin20014 Staelin2002 Stein1999Stephens1997 Stevenson1993, Stuart20011+ Sugi19933 Suzuki20010 Swanstrom1999T1997T1997 Tesluk19922 Tesluk19966 Tinkey19979 Torp-Pedersen19974 Tsai2002h5 Tsai2002h/Tungjitkusolmun20016Tungjitkusolmun20014Tungjitkusolmun20025Tungjitkusolmun2002 Vilgrain20019Vodopich20024 Vorperian20025 Vorperian2002 Wang199799 Wang20022*Watumull2000)Watumull2001/ Webster20013 Webster20016 Webster20014 Webster20025 Webster2002 Wendt19993 Wright20012+ Yabuki19939+ Yamaguchi1993* Young2000) Young2001 Yu1997k Yu20002! Yu20000" Yu20002 0)3 !"#$%&(-ed l03 ,oNr ceruercnse DP F,21 6MP1:305397r3@ X=DV8Xݐ@DVݤe@\{tr1fa\sn{if\nottlb\{2f\0nflif\hcraes0tT miseN weR mona};\{2f\3nflif\hcraes2tS myob;l}}\{ocoltrlbr\de\0rgee0nb\ul0e\;er2d55g\erne\0lbeu;0r\de\0rgee0nb\ul2e55};\{apdrp\alni\ 2f\0sf42{ u\ l21\6ap rMP1:305397}3}} ݐ@ DV ݤe AuthorsJournals Keywords '                               H  Aass, H. Abe, R. Ahmed, M. Amlie, J.P.Anfinsen, O.G. Arata, M. A. Arata, M.A.Aribandi, ManoharArmillotta, N. Baert, A.L.Bartolozzi, C. Bizzini, A. Bloom, D.A. Boaz, T. Boll, D.T. Brock, J. M. Brock, J.M. Brown, R. J.Browning, P.D.Buczkowski, A.K. Burdio, F. Burdio, J.M. Buscarini, E. Buscarini, L. Cao, H. Carrai, M. Castiella, T. Cavanna, L. Cavina, E. Chang, R.J.Chintapalli, Kedar N.Chopra, Shailendra Choy, Y. B.Christensen, N.E. Cicorelli, A. Cioni, D. Clark, T. W. Clark, T.W. Clouse, M. E. Clouse, M.E. Conrad, J.E. Conte, P.F. Corless, C.L. Cosman, E. Cosman, E.R. Cromeens, D. Curley, S.A. D, HaemmerichDavidson, B.S. Dawson, S.L. de Baere, T.De Gregorio, M.A.De, Scheerder, I De, Wever, I Denys, A. Di Stasi, M. DM., MahviDodd, Gerald D., III Donati, F. Enjoji, Y.etal F, MeloniFleming, J. B. Fleming, R.Y. Foerster, A. Fogle, R. Fornari, F.Frank, Mark S. FT, Lee Fujino, N. G, LeversonGarbagnati, F.Gazelle, G. S. Gazelle, G.S.Goldberg, S. N.Goldberg, S.N. Goletti, O. GS, Gazelle Gu, W. Z. Gu, W.Z. Guemes, A.Haemmerich, D. Hahn, P.F.Halpern, E. F. Halpern, E.F. Hansen, P.D. Hashimoto, T. Hoey, M.F. Horigome, H.Horigome, HideoHuertas, J. C. Huertas, J.C. Hulbert, J.C. Huth, J. F. Ikeda, T. Itoh, M. Itoh, Makoto Izzo, F. J, Webster Jacobs, G.H. Jacobs, T. Jesserun, J.Jeyarajah, D. R. Joh, T.Johns, Wood B. Johnson, C. Jones, C. D. Jones, C.D. Jones, D. B. Kanematsu, T. Kardache, M. Kato, Y.Kongsgaard, E.Kruskal, J. B. Kruskal, J.B. L, Solbiati Lassau, N. Lassman, C. Lazzaroni, S. Lee, D.Lee, F. T., Jr. Lencioni, R.Lenkinski, R.E.Leveillee, R.J. Lewin, J.S. Lindberg, G. Livraghi, T. Lorentzen, T. Lozano, R. Lu, D. S. M, Dellanoce Mahvi, D. M.Makachinas, T.T. Marchal, G.McGahan, J. P. McGahan, J.P. Meloni, F. Menu, Y. Merkle, E.M. MG, Curley Miao, Y. Monti, F. Moretti, M. Mueller, P.R. Mulier, P. Mulier, S. Murasaki, G. Nagy, A.G. Nakao, H.Nakao, Haruhisa Nashold, B.S. Ni, Y. Ninomiya, K.Nisenbaum, H. L.Nisenbaum, H.L. Nolsle, C.P. Nomura, T.Nomura, TomoyukiO'Connor, J.L. Ohara, H. Oliver, B. Oliver, B. S. Oliver, B.S. Organ, L.W. Owen, D.A. Paolicchi, A. Parker, J. Pathies, C.Patterson, E.J. Pellicano, S. Penninckx, F. PS, Hamilton Quaretti, P. Raman, S. S. Rege, R. V. RF, LaVeen Ricci, S. Rittman, W.J. Roche, A. Rogers, S.Rosenthal, D.I. Rossi, S. S, SironiS, TungjitkusolmunSaldinger, P. F. Saso, K. Saxon, L.A. Sayre, J. Schneider, P. Scott, D. J. Scott, Dj MdScudamore, C.H.Shankaranarayanan, A. Sheiman, R.G.Siperstien, A.E. SN, Goldberg Solbiati, L. Soulen, M. C. Soulen, M.C.Squassante, E. ST, StaelinStaelin, S. T. Stein, M.C.Stephens, L.C.Stevenson, W.G. Stuart, K. E. Sugi, K. Suzuki, T.Swanstrom, L.L. T, Ierace T, Livraghi Tesluk, H. Tinkey, P.Torp-Pedersen, S.T. Tsai, J. Z.Tungjitkusolmun, S. Vilgrain, V.Vodopich, D. J.Vorperian, V. R. Wang, K. Wang, M.Watumull, L. M.Webster, J. G. Wendt, M. Wright, A.S. Yabuki, S. Yamaguchi, T. Young, W. N. Yu, J.    Acad Radiol Acad.Radiol.Academic RadiologyAJR Am.J.Roentgenol.,&AJR. American Journal of Roentgenology(%Am. J. Roentgenol. Am. J. Roentgenol.American Heart Journal_d Ann.Surg.Applied NeurophysiologyyCancer J Sci AmEuropean Heart JournalEuropean RadiologyHepatogastroenterologyIEEE Trans Biomed Eng0+IEEE Transactions on Biomedical EngineeringInvestigative RadiologyJ Vasc Interv Radiol J.Surg.Res.J.Vasc.Interv.Radiol. Japanese Circulation JournalJournal of Endourology(#Journal of Gastrointestinal Surgery4.Journal of Vascular & Interventional Radiology(#Pacing & Clinical Electrophysiology Radiology($Seminars in interventional radiology submitted SurgerySurgical EndoscopyN Tumori  ' Xa$!*Atrial Fibrillation/su [Surgery]*Burns/et [Etiology]$ *Burns/pc [Prevention & Control]*Catheter Ablation,'*Catheter Ablation/ae [Adverse Effects],'*Catheter Ablation/is [Instrumentation] *Catheter Ablation/methods$*Catheter Ablation/mt [Methods]Ef$!*Contrast Media/pd [Pharmacology]*Electrocoagulation *Electrodes*Electromagnetic FieldsF *Electromagnetics*Electrosurgery *Electrosurgery/hi [History]*Endocardium/su [Surgery] *Heart Atrium/pa [Pathology]d *Heart Atrium/su [Surgery]tru*Heat*Hyperthermia, Induced0**Hyperthermia,Induced/is [Instrumentation]*Iron/pd [Pharmacology] *Laparoscopyl*Laparoscopy/mt [Methods]$*Liver Neoplasms/sc [Secondary] *Liver Neoplasms/su [Surgery]*Liver/bs [Blood Supply]*Liver/pa [Pathology] *Liver/pp [Physiopathology]*Liver/su [Surgery]*Models, Anatomic *Muscle,Skeletal/su [Surgery] *Nerve Tissue/su [Surgery]*Oxides/pd [Pharmacology]*Prostate/su [Surgery] *Radio Wavese0-*Saline Solution,Hypertonic/pd [Pharmacology]0-*Sodium Chloride/ad [Administration & Dosage],(*Spinal Nerve Roots/pp [Physiopathology]*Surgery/ed [Education](%*Tachycardia,Ventricular/su [Surgery] *Tomography, X-Ray Computed0 (Acrylic Resins)0 (Contrast Media) 0 (Oxides)$0 (Saline Solution,Hypertonic)0 (Suspensions)119683-68-0 (ferumoxides)7439-89-6 (Iron) 7647-14-5 (Sodium Chloride) 9003-05-8 (polyacrylamide)Acrylic Resins$ Adenocarcinoma/pathology/therapyadministration & dosageAdministration, CutaneousAdultAged analysistAnalysis of Variance Animal At4.Antineoplastic Agents/*administration & dosage("Atrial Fibrillation/pa [Pathology]tio$ Atrial Fibrillation/su [Surgery]y Atrial Flutter/pa [Pathology] Atrial Flutter/su [Surgery]y]Atrial Function,RightbloodBlood Loss,Surgical blood supplyBody Composition0+Body Temperature Regulation/ph [Physiology] Bovie WTBurnsBurns,Electric(%Burns/*etiology/*prevention & control Case ReportCatheter Ablation("Catheter Ablation/*adverse effects Catheter Ablation/*methods,&Catheter Ablation/is [Instrumentation]]$Catheter Ablation/mt [Methods] Cattleer Cell PhysiologyChronic DiseaseCold(#Colorectal Neoplasms/pa [Pathology]Combined Modality TherapyComparative Study complicationsContrast MediaDisease Models, AnimalDisease Models,AnimalDogs$Dose-Response Relationship,Drug($Doxorubicin/*administration & dosageElectric ConductivityElectric Impedance 03 "!##$%&&(((()--3! F  r 518,Radiofrequency current ablation of porcine right atrium: increased lesion size with bipolar two catheter technique compared to unipolar application in vitro and in vivo@:Anfinsen,O.G. Kongsgaard,E. Foerster,A. Aass,H. Amlie,J.P. 1998 1/1998*Catheter Ablation/ae [Adverse Effects] *Catheter Ablation/mt [Methods] *Heart Atrium/pa [Pathology] Animal Atrial Function,Right Catheter Ablation Catheter Ablation/is [Instrumentation] Comparative Study Electrodes Electrodes/ae [Adverse Effects] Female In Vitro injuries Lung Lung/pa [Pathology] Male Pericardium/pa [Pathology] Support,Non-U.S.Gov't Swine Temperature United States t-78*#Pacing & Clinical Electrophysiology21 1:Pt 1<6Bipolar lesions 65% greater in size. In vivo pig heartInterruption of atrial flutter and fibrillation by RF catheter ablation may be favored by large, elongated lesions. We administered RF current in unipolar and bipolar mode in porcine right atrium. Bipolar ablation was performed between the tip electrodes of two serially coupled catheters. With 4-mm tip electrodes in vitro, lesion length increased from a mean (SD) of 7.9 (1.2) mm at 3 mm-interelectrode distance (i.e.d.) to 13.3 (3.3) mm at 9-mm IED, but decreased at 12-mm IED due to nonconfluent lesions (P < 0.0001). With 4 mm distal electrodes and 8 mm IED, bipolar lesions were 65% longer than corresponding unipolar ablations. Switching to bipolar mode increased the lesion length more than increasing electrode tip length to 6 mm in unipolar mode. Power and temperature controlled ablation created equally sized lesions. Twelve anesthetized pigs were randomized to unipolar or two catheter bipolar temperature controlled ablation of the right atrial free wall. Bipolar ablation created confluent lesions with endocardial length x width of 13.5 (5.8) x 7.3 (3.7) mm, unipolar ablation 6.4 (2.8) x 4.6 (1.4) mm (P < 0.001 when comparing length and P = 0.013 for lesion width). The atrial lesions in both groups were transmural and extended into hilar lung lesions with maximal depth of 3.0 (1.1) and 2.6 (1.0) mm, respectively (P = 0.44). Five bipolarly and four unipolarly ablated pigs developed right diaphragmal paresis. We conclude that bipolar ablation may be preferable in situations where large, elongated lesions are favorable. The two catheter technique is feasible in porcine right atrium. Both bipolar and unipolar ablation of the porcine right atrial free wall may frequently be complicated by injury to the phrenic nerve and adjacent lung tissuelfDB - MEDLINE UI - 98134991 IN - Institute for Surgical Research, Rikshospitalet, Oslo, Norway. o.g.anfinsen@klinmed.uio.no JC - pab, 7803944 Journal Subset Index Medicus CP - United States PT - Journal Article LG - English EM - 19980318 Revised: 20001218. Entry Week: 19980318 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0147-8389 519,Bipolar radiofrequency catheter ablation creates confluent lesions at larger interelectrode spacing than does unipolar ablation from two electrodes in the porcine heart@:Anfinsen,O.G. Kongsgaard,E. Foerster,A. Amlie,J.P. Aass,H. 1998 7/1998*Catheter Ablation/is [Instrumentation] *Endocardium/su [Surgery] *Heart Atrium/su [Surgery] Animal Atrial Fibrillation/pa [Pathology] Atrial Fibrillation/su [Surgery] Atrial Flutter/pa [Pathology] Atrial Flutter/su [Surgery] Catheter Ablation Comparative Study Electrodes Endocardium/pa [Pathology] Female Heart Atrium/pa [Pathology] Human In Vitro Male methods Support,Non-U.S.Gov't Swine Treatment Outcome 1075-1084European Heart Journal197Bipolar (5mm distance) > Dielectric (two catheters 1mm apart simultaneous to ground electrode) > unipolar. Dielectric lesions at 5mm spacing were not confluent.@9AIMS: Radiofrequency catheter ablation of atrial flutter and fibrillation may be favoured by large, elongated lesions. We compared bipolar ablation with unipolar ablation from one or two electrodes in the porcine heart. METHODS AND RESULTS: In vitro, confluent lesions were reliably created by a 'dielectrode' catheter (energy delivered simultaneously (in parallel) from two 4 mm electrodes spaced 1 mm apart, towards an indifferent electrode), and a 'bipolar' catheter (energy delivered (in series) between two 4 mm electrodes spaced 5 mm apart). Sixteen anaesthetized pigs were randomized to standard unipolar (4), dielectrode (6) or bipolar (6) ablation. Two radiofrequency current deliveries of 30 s duration (70 degrees C) were administered to the inferior vena cava-tricuspid valve isthmus and two to the right atrial free wall in all animals. After 4 h, the lesions were examined macroscopically and histologically. Mean (SD) endocardial lesion length x width x depth measured 7.4 (2.4) x 5.4 (2.2) x 2.8 (0.8) mm in the standard unipolar mode, 10.2 (1.4) x 6.3 (0.7) x 3.3 (1.1) mm in the dielectrode mode and 14.0 (3.6) x 6.0 (1.7) x 3.8 (1.2) mm in the bipolar mode. Thus lesion length increased significantly through the three groups (P < 0.001), while width and depth did not. CONCLUSION: Both dielectrode and bipolar ablation were feasible in porcine right atrial ablation, and created longer lesions than the standard unipolar mode. By allowing a larger interelectrode distance, bipolar ablation created the longest lesions and may be favourable when linear lesions are necessaryvHBDB - MEDLINE UI - 98382772 IN - Medical Department B, Rikshospitalet, Oslo, Norway JC - em8, EM8, EM8, 8006263 Journal Subset Index Medicus CP - England PT - Journal Article LG - English EM - 19981208 Revised: 20001218. Entry Week: 19981208 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0195-668X60Arata,M.A. Nisenbaum,H.L. Clark,T.W. Soulen,M.C. 2001voPercutaneous radiofrequency ablation of liver tumors with the leveen probe: is roll-off predictive of response?LJ.Vasc.Interv.Radiol.c124l455-458h 4/2001Treat until impedance roll-off or 30min elapsed. LaVeen electrode. Local recurrence less with roll-off than without. Small study.C127 PM:11287532PJLiver Magnetic Resonance Imaging methods Recurrence United States analysisPURPOSE: The LeVeen radiofrequency (RF) probe uses roll-off of electrical impedance as the endpoint for RF cautery of hepatic tumors. The purpose of this study is to determine the relation of roll-off to local control of hepatic tumors. MATERIALS AND METHODS: Twenty hepatic tumors, including 10 hepatomas and 10 metastases, were treated. Lesions ranged from 1.4 cm to 6.0 cm in diameter; 13 (57%) were smaller than 3.0 cm. Each lesion was ablated with use of the LeVeen 15-gauge RF needle according to the manufacturer's protocol. Five patients underwent chemoembolization the day before. Patients were followed up with contrast-enhanced computed tomography or magnetic resonance imaging at 1 month and every 3 months thereafter. RESULTS: Among the 20 lesions, roll-off was achieved at all burn locations in 11 (55%), no burn locations in eight (40%), and two of three burn locations in one (5%). Roll-off was observed in all patients who had undergone chemoembolization the day before. Six local recurrences occurred, five after RF ablation without roll-off and one after RF ablation with roll- off. According to life-table analysis, the local recurrence rate at 6 months without roll-off was 43% and with roll-off was 15% (P =.024; OR = 8.3; 95% CI = 0.93-66). CONCLUSION: Roll-off is a significant predictor of local control after RF ablation. Strategies to enhance roll-off, such as concurrent embolization, may be important to optimize the therapeutic effect of this deviceUI - 21184242 LA - eng PT - Journal Article DA - 20010405 IS - 1051-0443 SB - IM CY - United States JC - BER RefMgr field[1]: Journal RefMgr field[8]: Not in File4-http://www.jvir.org/cgi/content/full/12/4/455'Divisions of Interventional Radiology (M.A.A., T.W.I.C., M.C.S.) and Ultrasound (H.L.N.), Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania de Baere,T. Denys,A. Johns,Wood B. Lassau,N. Kardache,M. Vilgrain,V. Menu,Y. Roche,A.c 2001nhRadiofrequency l\Ude Baere,T. Denys,A. Johns,Wood B. Lassau,N. Kardache,M. Vilgrain,V. Menu,Y. Roche,A.c 2001nhRadiofrequency liver ablation: experimental comparative study of water- cooled versus expandable systemsAJR Am.J.Roentgenol. 1761187-192 1/2001Model 30 vs. 3 electrode cooled-tip. Ex vivo bovine, in vivo pig. Cooled-tip larger. Cooled-tip more variable in vitro but not in vivo.Higher variability in vivo. RITA more spheric (Ratio of diameters). 4 lesions with RITA 30 did not coalesce. Uses formula for prolate ellipse.157 PM:111335649Animal blood Blood Loss,Surgical Catheter Ablation Cattle Comparative Study In Vitro instrumentation Liver methods pathology surgery Swine United States Water Hemorrhage2,OBJECTIVE. We evaluate the uniformity and reproducibility of thermal lesion ablation and quantify the volume of tissue destruction and hemorrhage induced with two different commercially available radiofrequency ablation devices. MATERIALS AND METHODS. A four-array anchor expandable needle electrode and a triple-cluster cooled-tip needle electrode were used to induce lesions in three explanted calf livers and in vivo in eight swine livers. The sizes of the radiofrequency-induced lesions were macroscopically evaluated by measuring two perpendicular dimensions immediately after the experiment. Bleeding was evaluated by weighing gauze swabs used to dry the hemorrhage caused by electrode insertions. RESULTS. In explanted liver, the mean diameter of the radiofrequency-induced lesion was 5.3 +/- 0.7 cm for the cooled-tip needle and 3.7 +/- 0.4 cm for the expandable needle (p = 0.042), which correspond to approximate volumes of 65.35 +/- 26.22 cm(3) and 26.67 +/- 9.59 cm(3), respectively (p < 0.002). In vivo, the mean diameter was 3.7 +/- 0.4 cm for the cooled- tip needle and 3 +/- 0.4 cm for the expandable needle (p < 0.0001), which correspond to approximate volumes of 24.18 +/- 7.56 cm(3) and 11.16 +/- 3.65 cm(3), respectively (p < 0.0001). Blood loss attained a median value of 3.5 g for the cooled-tip needle and 2.6 g for the expandable needle; this difference was not statistically significant (p = 0.06). CONCLUSION. The cooled-tip needle induced significantly larger lesions than the expandable needle, but the lesions produced by the expandable needle are more reproducible, uniform, and spheric. The larger size of the lesions produced by the cooled-tip needle may be attributed to the higher maximum power used by the generator and the higher energy deposition, which is due to the cooling of the needle electrodeUI - 20577986 LA - eng PT - Journal Article DA - 20010108 IS - 0361-803X SB - AIM SB - IM CY - UNITED STATES JC - 3AE RefMgr field[1]: Journal RefMgr field[8]: Not in FileU:3http://www.ajronline.org/cgi/content/full/176/1/187m'f_Service de Radiologie Interventionnelle, Institut Gustave Roussy, 94805 Villejuif Cedex, FranceU555ngEnhanced radiofrequency ablation of canine prostate utilizing a liquid conductor: the vi 555ngEnhanced radiofrequency ablation of canine prostate utilizing a liquid conductor: the virtual electrodeoHBLeveillee,R.J. Hoey,M.F. Hulbert,J.C. Mulier,P. Lee,D. Jesserun,J. 1996 2/1996LE*Catheter Ablation/mt [Methods] *Electrodes *Prostate/su [Surgery] Animal Body Composition Chronic Disease Disease Models,Animal Dogs Endosonography Fluoroscopy Male Necrosis Prostate Prostatic Hyperplasia/di [Diagnosis] Prostatic Hyperplasia/su [Surgery] secondary Temperature Treatment Outcome Ultrasonography United States 5-11Journal of Endourology101@9Decreased impedence with 14.6% saline injected before RFA Conventional radiofrequency (RF) ablative techniques have shown promise for the treatment of symptomatic benign prostatic hyperplasia (BPH); however, present RF technology is limited by the small lesion size, necessitating several probe placements and heating cycles to achieve sizable lesions. This limitation is attributable primarily to a rapid increase in electrical impedance secondary to tissue desiccation and charring at the electrode tip. We devised a hollow screw-tip needle electrode that permits fixation to tissue, recording of temperature and impedance, infusion of fluid, and delivery of RF energy. Infusion of electrolyte solution (i.e., saline) into tissue prevents impedance rise by conducting RF energy away from the metal electrode and permits the creation of large lesions. By varying the conductivity of the perfusate (concentration and temperature), lesions of large diameter can be created in a controlled manner. To determine the long-term tissue effects, we applied this new modified RF technique to the prostates of five mongrel dogs in a chronic (0.5 to 8-week) study. The screw-tip electrode was serially embedded into each lobe of the perineally exposed glands with 1-minute infusion of 0.9% saline (2 mL/min) followed by application of RF energy (500 KHz, 50 W, 2-18 minutes) along with continuous saline infusion. Thermocouples were embedded 5 mm below and at the gland capsule, and RF application was discontinued when the temperature reached 50 degrees C at the periphery. Postoperatively, the animals were examined daily for clinical status and weekly for glandular changes using transrectal ultrasonography. At predetermined intervals, the animals were sacrificed and the prostates excised, measured, sectioned, and examined for histologic changes. Ablative tissue temperatures of 50 to 100 degrees C were produced while impedance remained stable. Four animals required a single catheterization for relief of urinary retention between days 2 and 3; otherwise, all animals demonstrated a quick and uneventful recovery with no edema detectable on day 7 ultrasound examination. The outside dimensions of the gland remained relatively constant throughout the study (+ or - 0.39 cm L + W + H). Histologic examination revealed coagulation necrosis (ablation) in both lobes of all prostates (69.94% + or - 16.62% of the gland) with tissueless cavities forming from the ablation area (28.71% + or - 8.24% of the gland) contained within the capsule surrounded by healthy tissue at the periphery. Intraprostatic lesions were obtained without any gross damage to surrounding tissue, including the bladder and rectal wall. Utilizing a liquid conductor in prostate tissue allows a single electrode-placement heating cycle for controlled ablation for the potential treatment of BPH. This new technique produces more extensive and uniform lesions than conventional RF procedures, and lesion size is limited only by the duration of RF energy applicationXQDB - MEDLINE UI - 96430597 IN - Department of Urology, University of Minnesota, Minneapolis, USA JC - brj, BRJ, BRJ, 8807503 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 199705 Revised: 20001218. Entry Week: 199705 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0892-7790 @ 9<2 7 -,./68;+:39 !"#$(%&)*54?as 0.95 the first year, 0.84 the second year, 0.67 the third year, and 0.45 the fourth and fifth years. CONCLUSIONS: Percutaneous radiofrequency thermal ablation can be considered a useful new treatment for small hepatocellular carcinoma in patients without surgical prospects. It is simple, effective, and safe, and can be repeated in case of recurrence.XRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9166457'D=Department of Medicine, Hospital of Piacenza, Piacenza, Italyd tromagnetic FieldsF Electrode.enlRYwg Է(wgzbX\Refb[Hepatic lesion ablation with bipolar saline-enhanced radiofrequency in the audible spectrumrZSBurdio,F. Guemes,A. Burdio,J.M. Castiella,T. De Gregorio,M.A. Lozano,R. Livraghi,T.e 199911/1999,zAnimal Catheter Ablation In Vitro instrumentation Liver methods Necrosis pathology surgery Swine Temperature United StatesUI - 20350547 LA - eng PT - Journal Article DA - 20000727 IS - 1076-6332 SB - IM CY - UNITED STATES JC - CLV RefMgr field[1]: Journal RefMgr field[8]: Not in File680-686e Acad.Radiol.611Bipolar at 50Hz with 2 saline perfused electrodes 10cm apart. Ex vivo pig liver. Lesion size 144cm2 vs 62cm2. Also more homogeneous.b dk l RATIONALE AND OBJECTIVES: The authors' purpose was to create larger and more regular liver lesions in vitro by testing a new hyperthermia approach that uses a bipolar saline-enhanced electrode for radiofrequency (RF) in the audible spectrum and a greater power supply. MATERIALS AND METHODS: The authors' hyperthermia approach (group A, n = 23) was used in excised porcine livers, and the results were compared with those of a previously described monopolar saline-enhanced electrode procedure (group B, n = 23). In each set of experiments, RF in the audible spectrum current (50 Hz) was provided for 15 minutes with a similar ablation protocol. Electrical variables (impedance, current, voltage, power, and energy), temperatures in the lesions, volume size, regularity ratio of the lesion, and microscopic findings were measured. RESULTS: In group A, the mean volume size and the mean regularity ratio values were 144.8 cm3 +/- 59.8 and 0.78 +/- 0.1, respectively. In group B, the mean volume size and regularity ratio values were 62.1 cm3 +/- 36.4 and 0.62 +/- 0.1, respectively. The values in group B were thus significantly lower than those in group A (P < .01). The lesions in group A were also more homogeneous. No significant differences were found in electrical variables. CONCLUSION: The new bipolar saline-enhanced electrode produced larger, more regular, and more homogeneous lesions ex vivo than the previously used monopolar saline-enhanced electrode method. Using a greater power supply increased the amount of coagulative necrosis'VPSurgical Service A, Hospital Clinico Universitario Lozano Blesa, Zaragoza, Spain69 PM:10894071 <2Burdio, F. etal 2002Large Hepatic Ablation with Bipolar Saline-Enhanced Radiofrequency. An experimental study in in vivo porcine liver with a novel approach submittedi\Usaline-enhance bipolar lesions are large but very irregular. Unclear if true bipolar. 523,ztIncreasing catheter ablation lesion size by simultaneous application of radiofrequency current to two adjacent sites4.Chang,R.J. Stevenson,W.G. Saxon,L.A. Parker,J. 1993 5/1993*Catheter Ablation/mt [Methods] *Tachycardia,Ventricular/su [Surgery] Animal Catheter Ablation Catheter Ablation/is [Instrumentation] Cattle Electrodes Heart/ph [Physiology] In Vitro Temperature United States t-84American Heart Journal 125 5:Pt 1Bipolar > two electrodes with two generators > two electrodes in parallel from one generator. Uniform distance between electrodes. Ex vivo heart.vpTreatment of ventricular tachycardia by radiofrequency current application can be difficult, partly because of the larger size of the reentry circuit in relation to the lesion generated. Larger lesions than those currently achieved with single radiofrequency applications are desirable. This study evaluated simultaneous radiofrequency application to two adjacent electrodes to determine the effects of inter-electrode distance and configuration (bipolar serial vs parallel) on lesion size and tissue temperature. Two 6F electrodes were placed, with the tips facing each other, on bovine myocardium in a saline bath at 37 degrees C. Radiofrequency current was applied to a single electrode, or simultaneously to two electrodes connected either in series or in parallel. Tissue temperature, power, and lesion size were measured. Lesions produced by simultaneous radiofrequency delivery to both electrodes were more than twice the size of those produced by a single electrode alone (> 100 mm3 vs 33.2 mm3, p < 0.01). Temperatures between electrodes were greater than those temperatures at the same distances from a single electrode (p < 0.001). The size of the lesions increased as inter-electrode distance decreased below 3.5 mm (p < 0.030) because of the increasing depth of the lesion between the electrodes. Two electrodes placed in a bipolar as opposed to a parallel configuration were most efficient, as this configuration produced greater lesion sizes for a given level of power delivery (p < 0.0001). The bipolar lesion size decreased by > 50% if one electrode was not in contact with the tissue (p < 0.0004).(ABSTRACT TRUNCATED AT 250 WORDS)LFDB - MEDLINE UI - 93243196 IN - Department of Medicine, UCLA School of Medicine 90024 JC - 3bw, 3BW, 3BW, 0370465 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 199305 Revised: 20001218. Entry Week: 199305 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0002-8703lSZPYSZ(CYAJR Am.J.Roentgenol.CY48XUvBUvBq&q8X5h3bloodlSZPYSZ(CYAJR Am.J.Roentgenol.CY48XUvBUvBq&q8X5h3Blood Loss,SurgicalYSZ(CYAJR Am.J.Roentgenol.CY48XUvBUvBq&q 525,JCRadiofrequency lesion generation and its effect on tissue impedance<5Cosman,E.R. Rittman,W.J. Nashold,B.S. Makachinas,T.T. 1988 1988*Electromagnetic Fields *Electromagnetics *Heat *Radio Waves *Spinal Nerve Roots/pp [Physiopathology] Animal Electrodes Heat Monitoring,Physiologic Support,Non-U.S.Gov't Temperaturea230-242mApplied Neurophysiologyt51 2-58ZSImpedence changes with temperature. Early mention of possibility of bipolar probes.rThe method of radiofrequency heat lesion generation is reviewed with specific reference to the dorsal root entry zone. Experimental data on the impedance of electrolytic media as a function of temperature are reported, and their relation to what should be observed during radiofrequency lesioning in the body is commented upon. The future utility of impedance monitoring is discussed as well as possible implications of bipolar lesion electrode systemsJCDB - MEDLINE UI - 88268046 IN - Department of Physics, Massachusetts Institute of Technology, Cambridge JC - 6kk Journal Subset AIM Journals CP - Switzerland PT - Journal Article LG - English EM - 198808 Revised: 20001218. Entry Week: 198808 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0302-2773 rthermia,Induced/is [Instrumentation] *Liver/pp [Physiopathology] 449XQLaparoscopically guided bipolar radiofrequency ablation of areas of porcine liveroXRCurley,S.A. Davidson,B.S. Fleming,R.Y. Izzo,F. Stephens,L.C. Tinkey,P. Cromeens,D. 1997 7/1997*Catheter Ablation *Laparoscopy Adult Animal blood Electrodes Feasibility Studies Hemodynamics Liver Liver Function Tests Liver/su [Surgery] methods Necrosis Needles Swine729-733ISurgical Endoscopy117rklaproscopic in pigs, ground pad, two needles 3 cm apart, 2-2.5 cm lesions. No comparison to one electrode.BACKGROUND: Bipolar radiofrequency ablation (BRFA) is a promising technique with which to treat unresectable primary and metastatic liver tumors. Its effects on normal liver tissue and postoperative liver function, however, are unknown. We performed this study to determine (1) the feasibility of using laparoscopic ultrasound to guide placement of BRFA needle electrodes in the liver and (2) the histopathologic, hepatic biochemical, and systemic hemodynamic responses to BRFA. METHODS: Two BRFA lesions were created in the liver of adult domestic pigs to ablate 8-10% of the normal liver volume. Laparoscopic ultrasound was used to guide creation of one peripheral liver lesion and one central liver lesion (with a major hepatic or portal venous vein branch in the center of the BRFA lesions) in each animal. BRFA of liver tissue was performed by passing 12 W of RF power for 16 min across two 16-gauge active-needle electrodes placed 3 cm apart. RESULTS: All animals survived the procedure without significant hemodynamic alterations during or after BRFA. All animals had a transient elevation in serum transaminase levels that returned to normal within 1 week of the BRFA of liver tissue. Gross and microscopic histopathology of the BRFA lesions revealed 2.0-2.5-cm zones of complete coagulative necrosis around and between the BRFA needle tracks without destruction of major blood vessel walls. CONCLUSIONS: This study demonstrates (1) that laparoscopic ultrasound can be used to guide placement of BRFA needles in the liver and (2) that BRFA produces focal destruction of liver without significant systemic hemodynamic responses or alterations in liver function. Further studies of this technique to ablate malignant liver tumors are ongoingDB - MEDLINE UI - 97362338 IN - Department of Surgical Oncology, Box 106, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX, 77030, USA JC - vbf, VBF, VBF, 8806653 Journal Subset AIM Journals CP - Germany PT - Journal Article LG - English EM - 199707 Revised: 20001218. Entry Week: 199707 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0930-2794 p7d^Dodd, Gerald D., III Frank, Mark S. Aribandi, Manohar Chopra, Shailendra Chintapalli, Kedar N.|uRadiofrequency Thermal Ablation: Computer Analysis of the Size of the Thermal Injury Created by Overlapping Ablationsr 2001Am. J. Roentgenol.Am. J. Roentgenol.777-782i 177e4 >7http://www.ajronline.org/cgi/content/abstract/177/4/777October 1, 2001jdOBJECTIVE. The purpose of this study was to perform a computer analysis of the size of the thermal injury created by overlapping multiple thermal ablation spheres. MATERIALS AND METHODS. A computer-assisted design system was used to create three-dimensional models of a spherical tumor, a spherical tissue volume consisting of the tumor plus a 1-cm tumor-free margin, and individual spherical ablations. These volumes were superimposed in real-time three-dimensional space in different geometric relationships. The effect of the size and geometric configuration of the ablation spheres was analyzed with regard to the ability to ablate the required volume of tissue (tumor plus margin) without leaving untreated areas or interstices. RESULTS. The single-ablation model showed that if a 360{degrees} 1-cm tumor-free margin is included around the tumor targeted for ablation, radiofrequency ablation devices producing 3-, 4-, and 5-cm ablation spheres can be used to treat 1-, 2-, and 3-cm tumors, respectively. The six-sphere model, in which six ablation spheres are placed in orthogonal planes around the tumor, showed that the largest tumor that may be treated with a 3-cm ablation device is 1.75 cm, whereas 4- and 5-cm ablation spheres can be used to treat tumors measuring 3 and 4.25 cm, respectively. The 14- sphere model showed that addition of eight more spheres to the six-sphere model increased the treatable tumor size to 3, 4.6, or 6.3 cm, depending on the diameter of the ablation sphere used. For treating larger tumors, we found a cylindrical model to be less efficient but easier to control. CONCLUSION. Our computer analysis showed that the size of the composite thermal injury created by overlapping multiple thermal ablation spheres is surprisingly small relative to the number of ablations performed. These results emphasize the need for a methodic tumor ablation strategy. 350.B;Tissue ablation with radiofrequency using multiprobe arrays]VOGoldberg,S.N. Gazelle,G.S. Dawson,S.L. Rittman,W.J. Mueller,P.R. Rosenthal,D.I.g 1995 8/1995*Catheter Ablation/mt [Methods] *Liver/su [Surgery] Animal Cattle Comparative Study Heat Liver Liver/pa [Pathology] methods Necrosis Support,Non-U.S.Gov't United States670-674cAcademic Radiology2J8 2, 3 or 4 probes placed 1.5cm apart create larger lesions. 5 probes left central area without necrosis. Ex vivo calf. Simultaneous application of current from multiple probes created larger lesions than seuential application of current.~RATIONALE AND OBJECTIVES: We studied the feasibility of increasing the volume of tissue destroyed by radiofrequency tissue coagulation using multiprobe arrays and defined parameters that determine lesion size and shape. METHODS: Radiofrequency was applied to ex vivo calf liver using arrays of two to five 18-gauge probes for 6 min at 70-90 degrees C. Probe spacing (1-3 cm) and arrangement, as well as the method of radiofrequency application (simultaneous or sequential), were varied. The resulting areas of tissue coagulation were measured and compared. RESULTS: Uniform tissue necrosis was observed with simultaneous radiofrequency application for probes 1.5 cm or less apart. At 1.5 cm, arrays of three equidistant probes produced spheroid lesions approximately 3.0 +/- 0.2 cm in diameter. Arrays of four equidistant probes produced cuboid lesions of 3.2 +/- 0.1 cm per side. However, probes placed 2 cm or more apart produced independent lesions 1.4 cm in diameter, with incomplete necrosis between probes. In the trials using five-probe arrays, a central region 4mm in diameter showed no visible evidence of tissue necrosis. With each array, lesion size varied less than 3 mm in any direction. Greater necrosis was accomplished when radiofrequency was applied simultaneously rather than sequentially. CONCLUSION: Multiprobe radiofrequency arrays permit the destruction of more tissue in a single treatment session than is possible with multiple individual probes operating alone. Probes spaced 1.5 cm or less apart act synergistically, producing a total volume of coagulated tissue that is greater than when the individual probes are operated sequentially\VDB - MEDLINE UI - 98080893 IN - Department of Radiology, Massachusetts General Hospital, Boston 02114, USA JC - clv, clv, 9440159 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 199802 Revised: 20001218. Entry Week: 199802 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 1076-6332 450.rlTissue ablation with radiofrequency: effect of probe size, gauge, duration, and temperature on lesion volumeVOGoldberg,S.N. Gazelle,G.S. Dawson,S.L. Rittman,W.J. Mueller,P.R. Rosenthal,D.I. 1995 5/1995*Catheter Ablation *Heat *Liver/su [Surgery] *Muscle,Skeletal/su [Surgery] Animal Cattle Electrodes Liver Liver/pa [Pathology] methods Muscle,Skeletal/pa [Pathology] Necrosis Reproducibility of Results Temperature United Statesu399-404hAcademic Radiology2h5p~xLesion diameter increased with probe guage and duration of treatment (to max 6 min) but only to max 1.6cm. ex vivo calf.RATIONALE AND OBJECTIVES: We evaluated the parameters affecting the size and distribution of thermal tissue damage produced by radiofrequency electrodes. METHODS: Thermal lesions were produced by electrodes connected to a radiofrequency generator in specimens of liver (n = 143) and muscle (n = 20). Various combinations of probe tip exposure (0.5-8 cm), gauge (12-24 gauge), duration of treatment (0.5-12 min), and temperature (80-90 degrees C) were studied. The resulting volumes of tissue coagulation were measured and compared. RESULTS: Lesions equal to or less than 1.6 cm in diameter were symmetrically distributed around the electrode. Lesion diameter (but not length) increased with probe gauge and duration of treatment to a maximum of 6 min. However, lesions with mean diameters larger than 1.6 cm could not be produced using a single probe with any technique. Lesion length correlated with probe tip exposure from 1 to 8 cm (r2 = .996). Over the limited range investigated, increased temperature had minimal effects, except for tip exposures greater than 5 cm, in which larger and more uniform lesions resulted. Lesions varied equal to or less than 3 mm in diameter and equal to or less than 5 mm in length for each combination of variables. CONCLUSION: Radiofrequency ablation can accurately and reproducibly cause coagulative tissue necrosis. Necrosed tissue volume increases with length of exposed probe tip, larger probes, and sessions lasting at least 6 mintnDB - MEDLINE UI - 98080852 IN - Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA JC - clv, clv, 9440159 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 199802 Revised: 20001218. Entry Week: 199802 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 1076-6332ic foci, which were within 1 mm of the foci identified at histopathologic examination in seven of 12 animals (58%). After the administration of contrast material, foci devoid of previously visualized enhancement, which measured 7.3-15.0 mm, were identified. These were within 1 mm of the size of the foci identified at histopathologic examination in 11 of 12 animals (92%, P < .01). In two animals, enhancement depicted viable tumor, which appeared hyperechoic, on nonenhanced images. On delayed images, hyperec eter Ablation/is [Instrumentation]Radiofrequency tissue ablation: importance of local temperature along the electrode tip exposure in determining lesion shape and sizeVPGoldberg,S.N. Gazelle,G.S. Halpern,E.F. Rittman,W.J. Mueller,P.R. Rosenthal,D.I. 1996 3/1996analysis Animal Catheter Ablation Cattle Electrodes Heat In Vitro Liver methods Muscle,Skeletal Necrosis pathology surgery Swine Temperature United States Regression AnalysisUI - 96389370 LA - eng PT - Journal Article DA - 19961028 IS - 1076-6332 SB - IM CY - UNITED STATES JC - CLV RefMgr field[1]: Journal RefMgr field[8]: Not in File212-218 Acad.Radiol.33Temperature variation along probe varies with lengthing tip exposure and higher tip temperatures. Longer tips require higher temps. Max diameter at 90 C. RATIONALE AND OBJECTIVES: We determined whether heat distribution along a radiofrequency (RF) electrode would be uniform when longer tip exposures are used and whether local temperature effects would influence the shape of induced tissue coagulation. METHODS: Thermistors were embedded within 18-gauge RF electrodes at both ends and in the middle of the exposed tip. The length of tip exposure varied from 1 to 7 cm. RF was applied in vitro to pig liver for 6 min using a constant tip temperature, which was varied in 10 degrees C increments from 60 degrees C to 110 degrees C. Experiments were performed in triplicate. The 3- and 5-cm probes were used at a 90 degrees C tip temperature to create lesions in live pig liver and muscle using similar parameters. Temperature was measured throughout the procedure. Observable coagulation necrosis was measured at the end of the treatment. Regression analysis was used to evaluate the local temperature-lesion diameter relationship. RESULTS: Temperatures were not uniform along the tip exposure for any given trial. Temperature variation increased with higher tip temperatures and longer tip exposures. The diameter of local coagulation necrosis was a function of the local mean temperature. For in vitro trials, no coagulation was seen when the local temperature was less than 50 degrees C. Temperatures above this threshold resulted in progressively greater lesion diameter, with a minimum of 1 cm of necrosis occurring at 71 degrees C. Additional increases in lesion diameter (1.4-1.6 cm) were observed at approximately 90 degrees C. Mathematical modeling demonstrated a best-fit curve: lesion diameter (in cm) = ?1.4 + 0.03 (tip exposure)? ?1 - e [-0.067(local temp - 49.5 degrees C)]?, r2 = .986, SD = 0.14 cm for each curve. In living tissue, less uniformity in the shape of coagulation necrosis was seen around the electrodes. Local temperature-lesion diameter data fit the same logarithmic relation, but the threshold for coagulation necrosis was 8.5 degrees C higher than for in vitro specimens. CONCLUSION: Using a single-probe technique for RF-induced tissue necrosis, the diameter of tissue coagulation may be predicted by the local temperature along the exposed electrode. The uniformity of temperature decreases with increased tip exposures. This effect may be partially corrected by creating lesions at higher tip temperatures, where necrosis diameter is increased. Because effects are more pronounced in vivo, uniform volumes of tissue necrosis are limited to tip exposures of 3 cm or less'hbDepartment of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA166 PM:8796667 Xl33`ZVariables affecting proper system grounding for radiofrequency ablation in an animal model:3Goldberg,S.N. Solbiati,L. Halpern,E.F. Gazelle,G.S.  2000 9/200060*Burns/et [Etiology] *Burns/pc [Prevention & Control] *Catheter Ablation/ae [Adverse Effects] analysis Analysis of Variance Animal Disease Models,Animal Electrodes Equipment Design Liver Liver/in [Injuries] methods Statistics,Nonparametric Support,Non-U.S.Gov't Swine Temperature United States Burns Risk 1069-1075e4.Journal of Vascular & Interventional Radiology118rrkPURPOSE: The authors sought to determine which factors contribute to excessive thermal deposition and burns at the grounding pad site after high-current percutaneous, image-guided radiofrequency (RF) ablation. MATERIALS AND METHODS: Radiofrequency (1,000-2,000 mA) was applied for 10 minutes with use of an internally-cooled electrode placed into in vivo pig livers (n = 88). In separate experiments, the number of pads (1, 2, or 4), orientation of pads (horizontal, vertical, or diagonal), and distance between the pads and the electrode (10-50 cm) of mesh or foil grounding pads (12.5 x 8 cm; 100 cm2) were varied. Thermistors measured skin surface temperatures during ablation. Pathologic analysis of skin changes was performed. RESULTS: Temperature elevations at the grounding pad were observed for every trial, with a temperature elevation > or =12 degrees C (as high as 45 degrees C) observed in 60 of 88 trials (68.2%). Temperatures at the grounding site pad were dependent on all variables studied, including the grounding pad surface area, the amount of current deposited in the liver, the orientation of the pad, and the pad's distance from the electrode. Second-degree burns were seen with temperatures exceeding 47 degrees C and third-degree burns were observed when a temperature > or = 52 degrees C was noted. For a given set of RF parameters, reduced heating was observed for trials in which foil grounding pads were used (P < .001). Grounding pad burns did not occur at 2,000 mA (maximum generator output) when four foil pads were placed horizontally > or = 25 cm from the electrode. CONCLUSIONS: High-current RF ablation can induce severe burns at the grounding pad site if inadequate precautions are taken. To minimize the risk of burns, multiple large-surface-area foil pads should be placed on well-prepared skin and oriented with the longest surface edge facing the RF electrodefDB - MEDLINE UI - 20450279 IN - Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA. sgoldber@caregroup.harvard.edu JC - ber, BER, BER, 9203369 Journal Subset Index Medicus CP - United States PT - Journal Article LG - English EM - 20010202. Entry Week: 20010202 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 1051-0443    337.ZTRadiofrequency tissue ablation: increased lesion diameter with a perfusion electrodeF@Goldberg,S.N. Gazelle,G.S. Solbiati,L. Rittman,W.J. Mueller,P.R. 1996 8/1996 *Catheter Ablation/is [Instrumentation] Animal Cattle Electrodes In Vitro Liver Liver/pa [Pathology] Liver/su [Surgery] methods Muscle,Skeletal/pa [Pathology] Muscle,Skeletal/su [Surgery] Necrosis Perfusion Support,Non-U.S.Gov't Swine Temperature therapy United States636-644dAcademic Radiology3U8 leCooled tip electrode with 0C saline increases diameter of lesions ex vivo and in vivo (1.2 to 2.4 cm)8RATIONALE AND OBJECTIVES: We sought to induce large zones of coagulation necrosis using radiofrequency (RF) with perfusion electrodes and to define optimal parameters for this system. METHODS: We developed RF electrodes with internal cannulas to enable tip perfusion. Lesions were created with monopolar RF in ex vivo and in vivo liver and muscle tissue with and without perfusion of the electrode tip using 0 degree C saline. In separate experiments, wattage, current, procedure duration, tip exposure, and perfused tip temperatures were studied. RESULTS: In ex vivo liver tissue, a maximum lesion diameter of 3.1 cm without charring occurred with perfusion at 12 min and 50 W. In in vivo liver tissue with perfusion (tip temperature = 25-35 degrees C) and a 3-cm tip exposure, 80 W were deposited in muscle tissue and 65 W in liver tissue for 12 min without inducing charring. Lesion diameters were 4.5 cm and 2.4 cm, respectively. By comparison, without perfusion a maximum of 20 W could be deposited into either tissue type, resulting in 1.8-cm muscle lesions and 1.2-cm liver lesions. Tip temperatures between 45 degrees C and 55 degrees C resulted in charring. Smaller but predictable lesion diameters were created with a lower power, a shorter tip exposure, or both. Of all the parameters, diameter correlated best with the current applied. CONCLUSION: Perfusion of RF electrodes with chilled saline allows for increased power deposition without tissue charring, increasing the volume of coagulation necrosis created with a single electrode insertion. Perfusion electrodes therefore might decrease the number of probe insertions required for percutaneous tumor ablation therapy or allow for the treatment of larger lesionsltnDB - MEDLINE UI - 96389430 IN - Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA JC - clv, clv, 9440159 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 199610 Revised: 20001218. Entry Week: 199610 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 1076-6332 273Large-volume tissue ablation with radio frequency by using a clustered, internally cooled electrode technique: laboratory and clinical experience in liver metastasesrVOGoldberg,S.N. Solbiati,L. Hahn,P.F. Cosman,E. Conrad,J.E. Fogle,R. Gazelle,G.S.h 199811/1998d@9*Catheter Ablation/is [Instrumentation] *Catheter Ablation/mt [Methods] *Liver Neoplasms/sc [Secondary] *Liver Neoplasms/su [Surgery] Animal Cattle Colorectal Neoplasms/pa [Pathology] Electrodes Human Liver Liver/su [Surgery] methods Muscle,Skeletal/su [Surgery] Necrosis Support,Non-U.S.Gov't Swine United States,371-3792 Radiologyo 209a2a60Cluster of 3 cooled tip electrodes placed 0.5cm apart. In vivo pig liver lesion size increased from 1.8cm (one electrode) to 3.1cm. Simultaneous lesions larger than when current applied of each of three electrodes sequentially. Maximal results with pulsed technique. In 10 patients lesion size 4.5-7cm.zPURPOSE: To evaluate whether coagulation necrosis achievable with radio-frequency (RF) ablation can be increased by using a cluster of closely spaced electrodes. MATERIALS AND METHODS: RF was applied to ex vivo liver (n = 68), in vivo liver (n = 12), and in vivo muscle (n = 15) by using a cluster array of three separate internally cooled electrodes spaced 0.5 cm apart. The diameter of coagulation necrosis achieved with optimal RF deposition (1,400-2,150 peak mA) for 5-60 minutes of RF application was determined for electrode tip lengths of 1.5-3.0 cm and compared with that obtained by using a single electrode and otherwise similar technique. Ten patients with solitary intrahepatic colorectal metastases were also treated by using cluster electrode RF ablation. RESULTS: In ex vivo liver, simultaneous RF application to electrode clusters for 15, 30, and 45 minutes produced 4.7 cm +/- 0.1, 6.2 cm +/- 0.1, and 7.0 cm +/- 0.2 of coagulation necrosis, respectively. In in vivo liver and muscle, RF applied to electrode clusters for 12 minutes yielded 3.1 cm +/- 0.2 and 7.6 cm +/- 0.4 of coagulation, respectively. RF application to a single electrode produced maximal coagulation of 2.9 cm in ex vivo liver, 1.8 cm in in vivo liver, and 4.3 cm in muscle (P < .01, all tissues). In colorectal metastases, a single 12-15-minute application of RF to an electrode cluster induced 4.5-7.0 cm of coagulation necrosis. CONCLUSION: Simultaneous RF application to a cluster of three closely spaced internally cooled electrodes enables a larger volume of coagulation in ex vivo liver, in vivo tissues, and hepatic colorectal metastases than previously reportedxqDB - MEDLINE UI - 99024693 IN - Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA JC - qsh, QSH, QSH, 0401260 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 19981203 Revised: 20001218. Entry Week: 19981203 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0033-8419R  242}Percutaneous radiofrequency tissue ablation: optimization of pulsed-radiofrequency technique to increase coagulation necrosisRKGoldberg,S.N. Stein,M.C. Gazelle,G.S. Sheiman,R.G. Kruskal,J.B. Clouse,M.E.. 1999 7/1999*Catheter Ablation/mt [Methods] *Liver/pa [Pathology] Animal Cattle Electrodes In Vitro Liver Liver/su [Surgery] methods Muscle,Skeletal/pa [Pathology] Muscle,Skeletal/su [Surgery] Necrosis Support,Non-U.S.Gov't Swine Therapy,Computer-Assisted United StatesM907-916o4.Journal of Vascular & Interventional Radiology107 Pulsed current technique, describes empiric variable current technique with 10s high current and 15s low current, max current limited by impedence rise; in vivo liver lesion size increased from 2.9 to 3.7cmvpPURPOSE: To develop a computerized algorithm for pulsed, high-current percutaneous radiofrequency (RF) ablation, which maximally increases the extent of induced coagulation necrosis. MATERIALS AND METHODS: An automated, programmable algorithm for pulsed-RF deposition was designed to permit high-current deposition by periodically reducing current for 5-30 seconds during RF application. Two strategies for pulsed-RF deposition were evaluated: (i) constant peak current (900-1,800 mA) of variable duration and (ii) variable peak current (1,200-2,000 mA) for a specified minimum duration. The extent of induced coagulation was compared to results obtained with continuous (lower current) RF application. Trials were performed in ex vivo calf liver (n = 115) and in vivo porcine liver (n = 30) and muscle (n = 18) with use of 2-4-cm tip, internally cooled electrodes. RESULTS: For 3-cm electrodes in ex vivo liver, applying pulsed-RF with constant peak current for 12 minutes produced 3.5 cm +/- 0.2 of necrosis. Greater necrosis was produced with use of the variable current strategy, in which 4.5 cm +/- 0.2 of coagulation was achieved with use of an initial current > or =1,500 mA (minimum peak-RF duration of 10 sec, with 15 sec of reduced current to 100 mA between peaks; P < .01). This variable peak current algorithm also produced 3.7 cm +/- 0.6 of necrosis in in vivo liver, and 6.5 cm +/- 0.9 in in vivo muscle. Without pulsing, a maximum of 750 mA, 1,100 mA, and 1,500 mA could be applied in ex vivo liver, in vivo liver, and in vivo muscle, respectively, which resulted in 2.9 cm +/- 0.2, 2.4 cm +/- 0.2, and 5.1 cm +/- 0.4 of coagulation (P < .05, all comparisons). CONCLUSIONS: A variable peak current algorithm for pulsed-RF deposition can increase coagulation necrosis diameter over other ablation strategies. This innovation may ultimately enable the percutaneous treatment of larger tumorspjDB - MEDLINE UI - 99362062 IN - Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA JC - ber, BER, BER, 9203369 Journal Subset Index Medicus CP - United States PT - Journal Article LG - English EM - 19990908 Revised: 20001218. Entry Week: 19990908 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 1051-0443 . |- x11110950 2173 2000 DecPercutaneous tumor ablation: increased coagulation by combining radio-frequency ablation and ethanol instillation in a rat breast tumor model 827-31PURPOSE: To determine if percutaneously applied radio frequency (RF) combined with percutaneous ethanol instillation (PEI) can increase the extent of ablation in rat breast tumors. MATERIALS AND METHODS: R3230 mammary adenocarcinoma was implanted bilaterally in the mammary fat pads of 18 female rats. The tumor nodules measured 1. 2-1.5 cm. Eight tumors each were treated with (a) conventional, monopolar RF (96 mA +/- 28; 70 degrees C for 5 minutes); (b) PEI (250 microL of ethanol infused over 1 minute); (c) combined therapy of PEI immediately followed by RF ablation; or (d) combined therapy of RF ablation immediately followed by PEI. Four tumors were not treated and served as controls. Histopathologic examination included staining for mitochondrial enzyme activity. Resultant coagulation necrosis was compared between treatment groups. RESULTS: Coagulation necrosis was observed only within treated tumors. Tumors treated with RF alone had 6.7 mm +/- 0.6 of coagulation surrounding the electrode, and those treated with PEI alone had 6.4 mm +/- 0.6 of coagulation around the instillation needle (not significant). Significantly increased coagulation of 10.1 mm +/- 0.9 (P: <.001) was observed with the combined therapy of PEI followed by RF. RF followed by PEI did not increase coagulation (6.4 mm +/- 0.8 around the needle; not significant). CONCLUSION: PEI followed by RF ablation therapy increases the extent of induced coagulation necrosis in rat breast tumors, as compared with either therapy alone.'Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA. sgoldber@caregroup.harvard.eduPIGoldberg, S. N. Kruskal, J. B. Oliver, B. S. Clouse, M. E. Gazelle, G. S. 0033-8419 Journal Article RadiologyAdministration, Cutaneous Animal Catheter Ablation/*methods Combined Modality Therapy Ethanol/*therapeutic use Female Mammary Neoplasms, Experimental/*surgery Ratshttp://radiology.rsnajnls.org/cgi/content/full/217/3/827 http://radiology.rsnajnls.org/cgi/content/abstract/217/3/827 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=1111095010997473118 2000 Sep`ZVariables affecting proper system grounding for radiofrequency ablation in an animal model1069-75rlPURPOSE: The authors sought to determine which factors contribute to excessive thermal deposition and burns at the grounding pad site after high-current percutaneous, image-guided radiofrequency (RF) ablation. MATERIALS AND METHODS: Radiofrequency (1,000-2,000 mA) was applied for 10 minutes with use of an internally-cooled electrode placed into in vivo pig livers (n = 88). In separate experiments, the number of pads (1, 2, or 4), orientation of pads (horizontal, vertical, or diagonal), and distance between the pads and the electrode (10-50 cm) of mesh or foil grounding pads (12.5 x 8 cm; 100 cm2) were varied. Thermistors measured skin surface temperatures during ablation. Pathologic analysis of skin changes was performed. RESULTS: Temperature elevations at the grounding pad were observed for every trial, with a temperature elevation > or =12 degrees C (as high as 45 degrees C) observed in 60 of 88 trials (68.2%). Temperatures at the grounding site pad were dependent on all variables studied, including the grounding pad surface area, the amount of current deposited in the liver, the orientation of the pad, and the pad's distance from the electrode. Second-degree burns were seen with temperatures exceeding 47 degrees C and third-degree burns were observed when a temperature > or = 52 degrees C was noted. For a given set of RF parameters, reduced heating was observed for trials in which foil grounding pads were used (P < .001). Grounding pad burns did not occur at 2,000 mA (maximum generator output) when four foil pads were placed horizontally > or = 25 cm from the electrode. CONCLUSIONS: High-current RF ablation can induce severe burns at the grounding pad site if inadequate precautions are taken. To minimize the risk of burns, multiple large-surface-area foil pads should be placed on well-prepared skin and oriented with the longest surface edge facing the RF electrode.'Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA. sgoldber@caregroup.harvard.edu@:Goldberg, S. N. Solbiati, L. Halpern, E. F. Gazelle, G. S. 1051-0443 Journal ArticleJ Vasc Interv RadiolAnalysis of Variance Animal Burns/*etiology/*prevention & control Catheter Ablation/*adverse effects Disease Models, Animal Electrodes Equipment Design Liver/injuries Statistics, Nonparametric Support, Non-U.S. Gov't Swinelehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=109974736SRadio-frequency thermal ablation with NaCl solution injection: effect of electrical conductivity on tissue heating and coagulation-phantom and porcine liver studyleGoldberg,S.N. Ahmed,M. Gazelle,G.S. Kruskal,J.B. Huertas,J.C. Halpern,E.F. Oliver,B.S. Lenkinski,R.E. 2001 4/2001rl*Hyperthermia,Induced/is [Instrumentation] *Liver/pp [Physiopathology] *Saline Solution,Hypertonic/pd [Pharmacology] 0 (Saline Solution,Hypertonic) Animal Body Temperature Regulation/ph [Physiology] Dose-Response Relationship,Drug Electric Conductivity Electrodes Female Liver Liver/pa [Pathology] Male methods Support,Non-U.S.Gov't Swine Temperature United States157-165u Radiologys 219o1 VPPURPOSE: To characterize the effects of NaCl concentration on tissue electrical conductivity, radio-frequency (RF) deposition, and heating in phantoms and optimize adjunctive NaCl solution injection for RF ablation in an in vivo model. MATERIALS AND METHODS: RF was applied for 12-15 minutes with internally cooled electrodes. For phantom experiments (n = 51), the NaCl concentration in standardized 5% agar was varied (0%-25.0%). A nonlinear simplex optimization strategy was then used in normal porcine liver (n = 44) to determine optimal pre-RF NaCl solution injection parameters (concentration, 0%-38.5%; volume, 0-25 mL). NaCl concentration and tissue conductivity were correlated with RF energy deposition, tissue heating, and induced coagulation. RESULTS: NaCl concentration had significant but nonlinear effects on electrical conductivity, RF deposition, and heating of agar phantoms (P<.01). Progressively greater heating was observed to 5.0% NaCl, with reduced temperatures at higher concentrations. For in vivo liver, NaCl solution volume and concentration significantly influenced both tissue heating and coagulation (P<.001). Maximum heating 20 mm from the electrode (102.9 degrees C +/- 4.3 [SD]) and coagulation (7.1 cm +/- 1.1) occurred with injection of 6 mL of 38.5% (saturated) NaCl solution. CONCLUSION: Injection of NaCl solution before RF ablation can increase energy deposition, tissue heating, and induced coagulation, which will likely benefit clinical RF ablation. In normal well-perfused liver, maximum coagulation (7.0 cm) occurs with injection of small volumes of saturated NaCl solutionrlDB - MEDLINE UI - 21173758 IN - Department of Radiology of Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA JC - qsh, QSH, QSH, 0401260 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 20010419. Entry Week: 20010419 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0033-8419that coagulation necrosis occurred in preserving lobular structure. CONCLUSIONS: Percutaneous radiofrequency ablation therapy using a clustered electrode is a safe and effective treatment for liver tumor. Incomplete coagulation necrosis, however, can occur when percutaneous radiofrequency ablation therapy is performed for tumors located near large vesselsh'First Department of Internal Medicine, Nagoya City University Medical School, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya City, 467-8601 Japan170 PM:11268956a 578pSHepatic metastases: percutaneous radiofrequency ablation with cooled-tip electrodesBZSSolbiati L Goldberg SN Ierace T Livraghi T Meloni F Dellanoce M Sironi S Gazelle GSc 1997 1997<5RefMgr field[1]: Journal RefMgr field[8]: Not in File 367-373 Radiology  205uCooled tip electrode (tip T 20-25 C). 29 patients with 44 mets. 91% technical success. 34% local recurrence at 6 months. 33% disease-free survival at 18mos.l)*&4\VThermal lesions induced by 480 KHz localized current field in guinea pig and pig liver2+Rossi,S. Fornari,F. Pathies,C. Buscarini,L.m 1990 2/28/19902Animal Burns,Electric Electrocoagulation Guinea Pigs Heat injuries Liver Liver Neoplasms Male methods Necrosis Needles pathology surgery Swine Temperature UltrasonographyUI - 90208900 LA - eng PT - Journal Article DA - 19900504 IS - 0300-8916 SB - IM CY - ITALY JC - WJS RefMgr field[1]: Journal RefMgr field[8]: Not in File 54-57n Tumori761We evaluated the type, dimension and histopathological evolution of thermal lesions induced in guinea pig and pig liver by radiofrequency electrode needles at various temperatures for different exposure times. The greatest useful necrosis volume was induced by a needle of 1.1 mm diameter and exposed Up 10 mm long at 90 degrees C and 120 seconds exposure time. It was an ellipsoid with the biggest diameter of about 14 mm diameter and length of about 18 mm. It seems possible that liver tumors of not more than 20 mm diameter in patients without surgical prospects could be destroyed, ultrasonography guiding the needle into the tumor and using the temperature and exposure time mentioned above'@9Divisione di Medicina, Ospedale Civile di Piacenza, Italy202 PM:2181746piRossi, S. Di Stasi, M. Buscarini, E. Cavanna, L. Quaretti, P. Squassante, E. Garbagnati, F. Buscarini, L.d 1995rlPercutaneous Radiofrequency Interstitial Thermal Ablation in the Treatment of Small Hepatocellular CarcinomaCancer J Sci Am11 73. Bipolar info?9166457PURPOSE: Very few patients affected by hepatocellular carcinoma can undergo surgery, though it is considered the only curative therapy. We evaluated minimally invasive, percutaneous radiofrequency interstitial thermal ablation for treatment of patients with hepatocellular carcinoma who had no surgical prospects. PATIENTS AND METHODS: Twenty- four patients (16 men and 8 women; age range, 53 to 79 years) with 25 hepatocellular carcinoma nodules of not more than 3.0-cm diameter underwent radiofrequency interstitial thermal ablation treatment with the intent to achieve a cure. In each patient, the thermal necrosis volume achieved was about double the tumor volume. RESULTS: At the end of treatment, destruction of the tumor was achieved in all but two cases in which further thermal lesions were needed. During the mean follow-up interval of 24.8 months (range, 6-64), 13 of 24 patients had recurrences, 9 of whom underwent further radiofrequency thermal ablation treatment. Radiofrequency thermal ablation was again repeated in two patients who showed a second recurrence. A total of 36 hepatocellular carcinoma nodules in 24 patients were treated. No complications were observed. Seven patients died: three due to hepatic failure with advanced cancer, three due to heart failure, and one due to pneumonia. Cumulative survival curves indicated that the median survival time was 44 months and survival rate was 0.95 the first year, 0.84 the second year, 0.67 the third year, and 0.45 the fourth and fifth years. CONCLUSIONS: Percutaneous radiofrequency thermal ablation can be considered a useful new treatment for small hepatocellular carcinoma in patients without surgical prospects. It is simple, effective, and safe, and can be repeated in case of recurrence.XRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9166457'D=Department of Medicine, Hospital of Piacenza, Piacenza, ItalydrkScott, Dj Md Young, W. N. Watumull, L. M. Lindberg, G. Fleming, J. B. Rege, R. V. Brown, R. J. Jones, D. B.dVPDevelopment of an in vivo tumor-mimic model for learning radiofrequency ablation*#Journal of Gastrointestinal Surgery 200046 620-5TNAnimal Catheter Ablation/is [Instrumentation] *Catheter Ablation/mt [Methods] Comparative Study Disease Models, Animal Equipment Design Equipment Safety In Vitro *Liver Neoplasms/su [Surgery] Liver Neoplasms/us [Ultrasonography] *Models, Anatomic Sensitivity and Specificity Support, Non-U.S. Gov't *Surgery/ed [Education] Swine TexasztRadiofrequency ablation requires accurate probe placement using ultrasound guidance. The purpose of this study was to develop an in vivo tumor-mimic model for learning open and laparoscopic radiofrequency ablation. Tumor-mimics were created in ex vivo porcine livers by injecting a mixture of 3% agarose, 3% cellulose, 7% glycerol, and 0.05% methylene blue, which formed 1 cm hyperechoic, discrete lesions on ultrasound. Open and laparoscopic (using a box-trainer) ablation techniques were practiced. In vivo experiments were then conducted in 10 pigs. Three tumor-mimics were created in each animal using a laparoscopic approach. Lesions were characterized sonographically, ablated using an open (n = 5) or laparoscopic (n = 5) approach, and examined pathologically. An ablation in normal liver tissue was performed as a control. Tissue impedance was recorded. Target creation took 81 minutes per animal and 96% of injections were successful. Tissue impedance (48.8 +/- 5.8 vs. 49.6 +/- 5.4) and ablation size (25.1 +/- 3.4 vs. 24.3 +/- 5.1) were not significantly different for controls (n = 8) and tumor-mimics (n = 26), respectively. One animal died of a pulmonary embolism following injection of agarose into a hepatic vein. The agarose-based tissue-mimic creates realistic sonographic targets for learning ultrasound-guided open and laparoscopic radiofrequency ablation in an in vivo model.{Scott, D. J. Young, W. N. Watumull, L. M. Lindberg, G. Fleming, J. B. Huth, J. F. Rege, R. V. Jeyarajah, D. R. Jones, D. B.XRAccuracy and effectiveness of laparoscopic vs open hepatic radiofrequency ablationSurgical Endoscopy 2001152 135-40 Animal *Catheter Ablation/mt [Methods] Comparative Study Disease Models, Animal *Laparoscopy/mt [Methods] *Liver Neoplasms/su [Surgery] Probability Random Allocation Sensitivity and Specificity Statistics, Nonparametric Support, Non-U.S. Gov't Swine Treatment OutcomeBACKGROUND: The purpose of this study was to compare the accuracy (in terms of ultrasound-guided probe placement) and the effectiveness (in terms of pathologic tumor-free margin) of laparoscopic vs open radiofrequency (RF) ablation. METHODS: Using a previously validated tissue-mimic model, 1-cm simulated hepatic tumors were ablated in 10 pigs randomized to open or laparoscopic techniques. Energy was applied until tissue temperature reached 100 degrees C (warm-up) and thereafter for 8 min. A pathologist blinded to technique examined all specimens immediately after treatment. Analysis was by Fisher's exact test and the Mann-Whitney U test; p < 0.05 was considered significant. RESULTS: Off-center distance (3.5 +/- 1.6 vs 4.2 +/- 1.4 mm), size (24.7 +/- 3.1 vs 25.6 +/- 3.8 mm), symmetry (40% vs 73%), margin positivity (33% vs 9%), and margin distance (1.1 +/- 1.2 vs 2.2 +/- 1.6 mm) were not significantly different between laparoscopic (n = 15) and open (n = 11) ablations, respectively. The proportion of round/ovoid lesions (20% vs 64%) was lower (p = 0.043), and warm-up time (20.2 +/- 14.0 vs 10.7 +/- 7.5) was longer (p = 0.049) for the laparoscopic than for the open groups, respectively. CONCLUSION: Accurate probe placement can be achieved using laparoscopic and open RF ablation techniques. The physiologic effects of laparoscopy may alter ablation shape and warm-up time. Additional studies are needed to establish effective ways of achieving complete tumor destruction.umonia. Cumulative survival curves indicated that the median survival time was 44 months and survival rate was 0.95 the first year, 0.84 the second year, 0.67 the third year, and 0.45 the fourth and fifth years. CONCLUSIONS: Percutaneous radiofrequency thermal ablation can be considered a useful new treatment for small hepatocellular carcinoma in patients without surgical prospects. It is simple, effective, and safe, and can be repeated in case of recurrence.XRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9166457'D=Department of Medicine, Hospital of Piacenza, Piacenza, Italyd 579hLInitial studies of a novel bipolar probe for hepatic radiofrequency ablationVOStaelin ST Haemmerich D Tungjitkusolmun S Leverson G Lee FT Webster J Mahvi DM.G 2001 2001D>RefMgr field[1]: Unpublished Work RefMgr field[8]: Not in FileRLBipolar. Ex vivo bovine lesions 57% larger, in vivo pig lesions 200% larger. Unenacted Bill/Resolution  lCatheter Ablation  327ejdSaline-enhanced radio-frequency tissue ablation in the treatment of liver metastases. [see comments]pjLivraghi,T. Goldberg,S.N. Monti,F. Bizzini,A. Lazzaroni,S. Meloni,F. Pellicano,S. Solbiati,L. Gazelle,G.S. 1997 1/1997le*Catheter Ablation *Liver Neoplasms/sc [Secondary] *Liver Neoplasms/su [Surgery] *Sodium Chloride/ad [Administration & Dosage] 7647-14-5 (Sodium Chloride) Adult Aged Animal Cattle Female Human In Vitro Injections Liver Liver Neoplasms/ra [Radiography] Male methods Middle Age Necrosis Radiography,Interventional Swine Tomography,X-Ray Computed United Statesr205-210i Radiology  202V1rVPIn vivo pig lesion increased from 0.8 to 1.8-4.1cm with 1ml/min saline infusion.zPURPOSE: To assess the effect of intraparenchymal saline injection on the results of radio-frequency (RF) tissue ablation. MATERIALS AND METHODS: Ex vivo and in vivo animal RF ablation was performed with and without intraparenchymal saline injection. Initially, saline was injected as a bolus (1-20 mL) before RF application. For subsequent in vivo studies, saline was injected as a bolus before RF application or continuously (1 mL/min) during RF application. Finally, 14 patients with liver metastases and one patient with primary cholangiocarcinoma were treated with the continuous infusion technique. A single RF electrode (tip exposure, 1-3 cm) was used with various ablation parameters. RESULTS: With pretreatment bolus injection of saline, lesions measured 1.4 cm +/- 0.1, 1.6 cm +/- 0.2, and 1.2 cm +/- 0.1 in ex vivo liver, in vivo animal muscle, and in vivo animal liver, respectively. Without saline enhancement, lesion sizes were 1.0 +/- 0.2, 1.2 +/- 0.2, and 0.8 +/- 0.1 cm, respectively. With continuous saline injection in in vivo pig liver, lesion size was 1.8 - 4.1 cm in diameter. In human tumors, necrosis volume was variable, but complete necrosis was seen in 13 of 25 lesions (diameter, 1.2-3.9 cm). Partial necrosis greater than 50% was seen in 12 lesions (diameter, 1.5-4.5 cm). CONCLUSION: Saline-enhanced RF ablation might permit percutaneous destruction of large liver lesionsDB - MEDLINE UI - 97141962 IN - Department of Radiology, Ospedale Civile, Vimercate (Milan), Italy CM - Comment in: Radiology. 1997 Nov;205(2):582-4 JC - qsh, QSH, QSH, 0401260 Journal Subset AIM Journals CP - United States PT - Journal Article LG - English EM - 199701 Revised: 20001218. Entry Week: 199701 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0033-84190The loop electrode: in vitro evaluation of a device for ultrasound- guided interstitial tissue ablation using radiofrequency electrosurgeryL Lorentzen,T. 1996 3/1996Animal Cattle Electrosurgery In Vitro instrumentation Liver methods surgery Ultrasonography Ultrasonography,Interventional United StatesUI - 96389371 LA - eng PT - Journal Article DA - 19961028 IS - 1076-6332 SB - IM CY - UNITED STATES JC - CLV RefMgr field[1]: Journal RefMgr field[8]: Not in File219-224h Acad.Radiol.33Loop with radius 1 cm, rotated 360. Ex vivo calf. Cuts spherical tissue section with thin stalk of coagulated tissue. No histo."RATIONALE AND OBJECTIVES: I developed and tested in vitro a device for ultrasound-guided monopolar radiofrequency (RF) electrosurgical interstitial tissue ablation. METHODS: The current was applied to an electrode with a distal loop form (radius = 1 cm). The superelastic properties of the electrode allowed cannula introduction in the experimental medium (calf liver) before subsequent rotation of the electrosurgical cutting electrode, resulting in cutting off and isolation of a spherical lesion interstitially. The optimal setting of the RF unit and the optimal cutting speed were evaluated. Under ultrasonographic guidance and monitoring, approximately 150 lesions were produced with different loop designs and sizes. The gross appearance was evaluated and correlated to ultrasonography. RESULTS: An output effect of 200 W was optimal for resection and cutting with the loop electrode. An ellipsoid loop configuration could produce an almost spherical lesion with a diameter of 2.0 cm interstitially. Ultrasonography could guide the introduction of the loop electrode into tissue and visualize the upper part of the lesion. CONCLUSION: The loop electrode is a technique for percutaneous ultrasonographically guided tissue ablation. It was proved to be efficient in vitro by producing 2- cm liver lesions'RLDepartment of Ultrasound, Herlev Hospital, University of Copenhagen, Denmark165 PM:8796668A cooled needle electrode for radiofrequency tissue ablation: thermodynamic aspects of improved performance compared with conventional needle design Lorentzen,T. 1996 7/1996Animal Catheter Ablation Cattle Electrodes,Implanted Equipment Design In Vitro instrumentation Irrigation Liver methods Needles Perfusion surgery Temperature United States WaterUI - 96389420 LA - eng PT - Journal Article DA - 19961029 IS - 1076-6332 SB - IM CY - UNITED STATES JC - CLV RefMgr field[1]: Journal RefMgr field[8]: Not in File556-563 Acad.Radiol.374.Initial ex vivo study of cooled tip electrode.RATIONALE AND OBJECTIVES: I developed and tested a cooled needle electrode (CNE) for radiofrequency (RF) tissue ablation in vitro. METHODS: A 2-mm needle electrode with two lumina for internal water perfusion and irrigation of the needle tip and a conventional needle electrode were tested in ex vivo calf liver during different levels of output power (wattage). RF lesions produced by the two needle types were further evaluated with a thermal camera. RESULTS: When the CNE was used, a significant increase in the duration of ablation was observed, which caused a significant increase in delivered energy and lesion size when compared with the conventional needle electrode. The largest lesion produced with the CNE was almost spherical and measured 41 x 37 mm (longitudinal x transverse). The cooling effect was reflected in the image obtained with the thermal camera. CONCLUSION: This technique produced very large lesions compared with conventional methods and may have a role in many different kinds of RF needle ablation'ZTDepartment of Ultrasound, Herlev Hospital, University of Copenhagen, Herlev, Denmark163 PM:8796717trocoagulationztRadiofrequency tissue ablation with a cooled needle in vitro: ultrasonography, dose response, and lesion temperatureBDepartment of Radiology, University Hospitals, Leuven, Belgium152 PM:9271273 eter Ablation/is [ 224Gd^Treatment of VX2 liver tumor in rabbits with "wet" electrode mediated radio-frequency ablationRKMiao,Y. Ni,Y. Mulier,S. Yu,J. De,Wever,I Penninckx,F. Baert,A.L. Marchal,G.  2000 2000*Electrosurgery *Liver Neoplasms/su [Surgery] Animal Electrodes Laparotomy Liver Lung Male mortality Rabbits Survival Rate therapy188-194 European Radiology101 Measures long-term survival in VX2 model after open RFA with saline infusion. 33% local recurrence or lung mets. Immediate histology with preserved cellular architecture. Delayed histology with coagulative necrosis.sRadio-frequency ablation (RFA) has been considered as an alternative therapy for liver tumors. A "wet" electrode with interstitial infusion of hypertonic saline was tested for the RFA of liver tumor in rabbits. Seventy-eight liver tumors ( 1.5 to 3.0 cm) were induced in 41 rabbits by VX2 carcinoma implantation. Fifty-one tumors in 27 rabbits were treated with RFA. Under laparotomy, the RF energy was delivered while 5 % saline was infused through the electrode into the tumor at 1 ml/min. Six rabbits with 12 tumors were treated with only intratumoral 5 % saline infusion without RFA. Another 8 rabbits with 15 tumors received sham operation as untreated controls. The efficacy of the therapy was evaluated with survival rate, MRI, microangiography, and histopathology. In the RFA group, 6 rabbits survived longer than 6 months (absolute eradication rate 22.2 %); 12 rabbits were found free of viable tumor at the moment when they were sacrificed (relative eradication rate 44.4 %); 9 rabbits showed local tumor relapse and/or lung metastasis 2-10 weeks after ablation (recurrent rate 33.3 %). In control groups of saline infusion and sham operation, all 14 rabbits died within 3 months (mortality rate 100 %). Three-month survival rates between RFA group and control groups were significantly different (p < 0.05). Findings of MRI, microangiography, and histology supported these outcomes. Radical treatment of liver malignancy in rabbits is possible with the present modified RFA technique. Its clinical usefulness has to be further provenf_DB - MEDLINE UI - 20130896 IN - Department of Radiology, University Hospitals, Herestraat 49, Gasthuisberg, B-3000 Leuven, Belgium JC - cl3 Journal Subset Index Medicus CP - Germany PT - Journal Article LG - English EM - 20000229 Revised: 20001218. Entry Week: 20000229 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0938-7994B"!gulation *Nerve Tissue/su [Surgery]47jcA comparative study on validation of a novel cooled-wet electrode for radiofrequency liver ablation$Miao,Y. Ni,Y. Yu,J. Marchal,G. 2000 7/2000*Catheter Ablation/is [Instrumentation] *Liver/su [Surgery] 7647-14-5 (Sodium Chloride) Animal Catheter Ablation/mt [Methods] Cattle Cold Comparative Study Electrodes Equipment Design Liver methods Perfusion Sodium Chloride Temperature United States 438-444tInvestigative Radiology 357 PJRATIONALE AND OBJECTIVES: A cooled-wet electrode has been developed for radiofrequency ablation (RFA) that allows simultaneous internal-cooling perfusion ("cooled") and interstitial hypertonic saline infusion ("wet"). The present comparative study was conducted to validate this new device for the increased coagulation volume in RFA. METHODS: Under low-power (50 W, groups A through F) and high-power (90 W, groups A' through F') control modes, 240 RFA lesions were created on excised beef liver to compare the cooled-wet electrode with other monopolar electrodes. The experimental regimens were as follows: groups A and A', conventional RF electrode; groups B and B', cooled electrode; groups C and C', wet electrode; groups D and D', cooled-wet electrode; groups E and E', cooled-wet electrode but suspended wet function; and groups F and F', cooled-wet electrode but suspended cooled function. The ablation efficacy was evaluated by comparing the lesion sizes as well as parameters of impedance, power output, current, and tip temperature. RESULTS: With lower impedance and tip temperature but higher power output, the lesion size in groups D (4.90 +/- 0.60 cm) and D' (6.6 +./- 0.99 cm) was significantly larger than that in other groups. CONCLUSIONS: The use of the cooled-wet electrode could efficiently increase the lesion size for liver ablation`ZDB - MEDLINE UI - 20356267 IN - Department of Radiology, University Hospitals, Leuven, Belgium JC - gwk, GWK, GWK, 0045377 Journal Subset Index Medicus CP - United States PT - Journal Article PT - Validation Studies LG - English EM - 20001103. Entry Week: 20001103 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0020-999659@:A novel "cooled-wet" electrode for radiofrequency ablation:3Ni,Y. Miao,Y. Mulier,S. Yu,J. Baert,A.L. Marchal,G. 2000 2000 *Catheter Ablation/is [Instrumentation] *Electrodes 7647-14-5 (Sodium Chloride) Animal Cattle Cold Electric Impedance Electrodes Equipment Design Liver Liver/pa [Pathology] Liver/su [Surgery] Necrosis Power Sources Sodium Chloride Surface Properties Swine Temperature852-854European Radiology105ed^In the light of growing demands for improved applicability of radiofrequency ablation (RFA), recently we have developed a novel "cooled-wet" electrode by taking the advantages of both internally cooled and saline-enhanced electrodes. The efficacy of the electrode was evaluated in both ex vivo and in vivo liver RFA under both low and high power output levels. The ablation volume created with the "cooled-wet" electrode appeared to be much larger than that reported up to now with the use of other monopolar electrodes. The mechanisms on how this device optimizes the RF energy delivery are also discussedB;DB - MEDLINE UI - 20281153 IN - Department of Radiology, University Hospitals, Leuven, Belgium JC - cl3 Journal Subset Index Medicus CP - Germany PT - Journal Article LG - English EM - 20000808 Revised: 20001218. Entry Week: 20000808 RefMgr field[1]: Journal RefMgr field[8]: Not in File RefMgr field[26]: 0938-7994 ' Electrocoagulation Electrocoagulation/*methods,'Electrocoagulation/is [Instrumentation]$Electrocoagulation/mt [Methods] Electrodese SElectrodes, ImplantedElectrodes,Implanted$Electrodes/ae [Adverse Effects]taElectrophysiologyElectrosurgery(#Electrosurgery/is [Instrumentation] Endocardium/pa [Pathology]]y]Endosonography($Endothelium, Vascular/pa [Pathology] Endothelium/pa [Pathology]Equipment DesignEquipment SafetyEthanol/*therapeutic useFeasibility Studies FemaleodeFinite Element Analysis FluoroscopyFollow-Up Studies Guinea Pigs Heart Atrium/pa [Pathology]y]Heart/ph [Physiology]Heatt HemodynamicsS Hemorrhagetes Hepatic Veins/pa [Pathology]$Hepatic Veins/ra [Radiography]$History of Medicine,19th Cent.Human In Vitroe InjectionsInjections, Intralesional injurieseinstrumentationonIron/du [Diagnostic Use] Irrigation Laparotomy Life TablesLiverLiver CirculationLiver Function TestsLiver Neoplasms Liver Neoplasms,Experimental$Liver Neoplasms/di [Diagnosis]$ Liver Neoplasms/ra [Radiography]$Liver Neoplasms/sc [Secondary] Liver Neoplasms/su [Surgery]Liver Neoplasms/surgery($Liver Neoplasms/us [Ultrasonography]Liver/bs [Blood Supply]Liver/in [Injuries]Liver/injuriesLiver/pa [Pathology]Liver/pathology/*surgeryLiver/ra [Radiography]Liver/su [Surgery]ts Liver/us [Ultrasonography]LungrLung/pa [Pathology]rs Magnetic Resonance ImagingSZMale/,(Mammary Neoplasms, Experimental/*surgery82Mammary Neoplasms, Experimental/pathology/*therapy methodsorMice Mice, Nude$Microcirculation/pa [Pathology]$Microscopy, Video/mt [Methods] Middle AgeModels, CardiovascularMonitoring,Physiologic [P mortalityMuscle,Skeletal$Muscle,Skeletal/pa [Pathology] Muscle,Skeletal/su [Surgery] Necrosisn Needless ,)Neoplasm Recurrence, Local/di [Diagnosis] Neoplasms Oxides/du [Diagnostic Use] pathology Perfusion Pericardium/pa [Pathology]ectPhantoms,Imaging physiologyPilot Projects Portal Vein/pa [Pathology] Portal Vein/ra [Radiography] Portraits Power Sources ProbabilityProspective Studies Prostate($Prostatic Hyperplasia/di [Diagnosis]("Prostatic Hyperplasia/su [Surgery] Rabbits Radio Waves Radiography,InterventionalRandom AllocationRatsRats, Inbred F344 RecurrenceesoRegional Blood FlowRegression Analysis Reproducibility of ResultsRisk Safety secondary Sensitivity and SpecificitySodium Chloride SoftwareStatistics, NonparametricStatistics,Nonparametric$ Stomach Neoplasms/pa [Pathology]Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.Support,Non-U.S.Gov'tSupport,U.S.Gov't,P.H.S.Surface Properties surgerygy Survival Rate SuspensionsSwine Temperature-UTexastherapeutic use therapyTherapy,Computer-AssistedThermodynamics Time Factors Tomography, X-Ray ComputedTomography,X-Ray ComputedTreatment OutcomeUltrasonography$Ultrasonography,Interventional United StatesWater, Radiofrequency ablation lesions in a pig liver modelHAHansen,P.D. Rogers,S. Corless,C.L. Swanstrom,L.L. Siperstien,A.E.n 199911/1999Animal blood Laparotomy Liver Liver Circulation Liver Neoplasms,Experimental m