Volume Of Coagulation Necrosis Research Articles

Radiofrequency Ablation of Normal Lungs after Pulmonary Artery Embolization with Use of Degradable Starch Microspheres: Results in a Porcine Model

The present study was performed to evaluate the effect of pulmonary artery embolization on radiofrequency (RF) ablation of normal porcine lungs. RF ablation zones (n=34) were created in the normal lungs of five domestic pigs (five zones in each of the first two pigs and eight zones in each of the remaining three pigs) with an expandable multitined electrode with use of bilateral thoracotomy. RF ablation was performed without pulmonary artery embolization (group 1, n=8), immediately after embolization (group 2, n=11), 15 minutes after embolization (group 3, n=7), and 30 minutes after embolization (group 4, n=8) with degradable starch microspheres. Among them, 12 ablation zones were excluded from this study because they were considerably limited by the presence of the pleura or large bronchi. The remaining 22 zones were included (n=7, n=5, n=4, and n=6 in groups 1, 2, 3, and 4, respectively). Coagulation necrosis volumes in the ablation zones were measured and compared among the groups. Coagulation necrosis volumes were 0.9+/-0.5 cm3, 2.1+/-0.4 cm3, 2.1+/-1.0 cm3, and 1.9+/-0.6 cm3 in groups 1, 2, 3, and 4, respectively. Groups 2-4 showed significantly larger coagulation volumes than group 1 (P=.012, P=.023, and P=.010 in groups 2, 3, and 4, respectively). Pulmonary artery embolization contributed to larger volumes of coagulation necrosis after RF ablation of normal lungs.

Thoracoscopic ethanol injection and radiofrequency ablation for the treatment of hepatocellular carcinoma located immediately under the diaphragm

We previously reported that the combination therapy of percutaneous ethanol injection and radiofrequency ablation (PEI-RFA) was more effective than RFA alone in inducing wider coagulated necrosis for the treatment of hepatocellular carcinoma (HCC). In the present study, we thoracoscopically applied the combination therapy to the treatment of HCC located immediately under the diaphragm. RFA electrode and ethanol injection needle were inserted into the tumor through the right side of the diaphragm in 6 patients with HCC close to the diaphragm. In all cases, the tumor was completely ablated with enough safety margin around the tumor. No local tumor recurrence has been observed in a relatively short-time follow-up period. The volume of coagulated necrosis and the energy requirement for coagulation in thoracoscopic ethanol injection and RFA (T-EI-RFA) were comparable to those of PEI-RFA. Although HCC located immediately under the diaphragm is difficult to treat with a percutaneous approach due to the poor visualization by ultrasonography, T-EI-RFA is considered to be an effective treatment modality.

Percutaneous radiofrequency ablation of renal tumors: Midterm results in 16 patients

Purpose To evaluate the outcome of 16 patients after percutaneous radiofrequency ablation of renal tumors. Materials and methods Sixteen patients (nine women, seven men; mean age, 61 ± 9 years) with 24 unresectable renal tumors (mean volume, 4.3 ± 4.3 cm 3) underwent CT-guided ( n = 20) or MR imaging-guided ( n = 4) percutaneous radiofrequency ablation using an expandable electrode (Starburst XL™, RITA Medical Systems, Mountain View, CA) with a 150-W generator. The initial follow-up imaging was performed within 1–30 days after RF ablation, then at 3–6 month intervals using either CT or MRI. Residual tumor volume and coagulation necrosis was assessed, and statistical correlation tests were obtained to determine the strength of the relationship between necrosis volume and number of ablations. Results Overall, 97 overlapping RF ablations were performed (mean, 3.5 ± 1.5 ablations per tumor) during 24 sessions. Five or more RF ablations per tumor created significant larger necrosis volumes than 1–2 ( p = .034) or 3–4 ablations ( p = .020). A complete ablation was achieved in 20/24 tumors (primary technical success, 83%; mean volume of coagulation necrosis: 10.2 ± 7.2 cm 3). Three of four residual tumors were retreated and showed complete necrosis thereafter. Three major complications (one percuatneous urinary fistula and two ureteral strictures) were observed after RF ablation. No further clinically relevant complications were observed and renal function remained stable. During a mean follow-up of 11.2 months (range, 0.2–31.5), 15/16 patients (94%) were alive. Only one patient had evidence of local recurrent tumor. Conclusion The midterm results of percutaneous RF ablation for renal tumors are promising and show that RF ablation is well-suited to preserve renal function.

Time-lag performance of radiofrequency ablation after percutaneous ethanol injection for the treatment of hepatocellular carcinoma

We have previously reported that the combination therapy of percutaneous ethanol injection and radiofrequency ablation (PEI-RFA) was more effective than RFA alone to induce wider coagulated necrosis for the treatment of hepatocellular carcinoma (HCC). In the present study, the effect of time-lag performance of RFA after PEI was evaluated under the same ablation condition as PEI-RFA by analyzing the volume of coagulated necrosis, the energy requirement for ablation and the amount of ethanol injected into HCC. The comparative study between time-lag PEI-RFA and no time-lag PEI-RFA showed that the total energy requirement and the energy requirement per unit volume for whole and marginal coagulated necrosis were significantly smaller in the time-lag group than in the no time-lag PEI-RFA group. In time-lag PEI-RFA, the volume of coagulated necrosis induced positively correlated with the amount of ethanol injected into HCC as previously observed in PEI-RFA treatment. These results suggest that time-lag PEI-RFA can induce comparable coagulated necrosis with a smaller energy requirement than no time-lag PEI-RFA, and that time-lag PEI-RFA is likely to be less invasive than no time-lag PEI-RFA for inducing comparable coagulated necrosis. Thus, time-lag performance of RFA after PEI may make RFA treatment more effective and less invasive for the treatment of patients with HCC.

Heating and Coagulation Volume Obtained with High-Intensity Focused Ultrasound Therapy: Comparison of Perflutren Protein-Type A Microspheres and MRX-133 in Rabbits

To compare the efficiency of different microbubble contrast agents in the heating and coagulation of rabbit liver tissue by using high-intensity focused ultrasound therapy. The use of and protocols for Japan white rabbits were approved by the University of Tokyo Committee on Animal Resources. In vitro experiments were conducted in a 1-mL cylindric space of polyacrylamide gel, which contained different microbubble contrast agents (MRX-133 or perflutren protein-type A microspheres). In vivo experiments were performed in six Japan white rabbits (two for the perflutren protein-type A microsphere group, two for the MRX-133 group, and two for the control group). In each rabbit, the liver was directly subjected to high-intensity focused ultrasound after intravenous injection of different microbubble contrast agents. Natural saline was used as a control. High-intensity focused ultrasound was applied for 30 seconds by using a 2.18-MHz transducer, and the temperature increase and volume of coagulation necrosis were evaluated. Statistical analysis was performed by using an analysis of variance test, which was followed by a Student-Newman-Keuls test; a P value of <.05 was considered to indicate a statistically significant difference. In the MRX-133 group, the mean temperature increase was significantly greater and faster than that in the control group (P < .01) or in the perflutren protein-type A microsphere group (P < .05). In the perflutren protein-type A microsphere group, the mean temperature increase was greater and faster than that of the control group (P < .01) for both in vitro and in vivo experiments. The mean volume of the coagulation necrosis lesion was 117.9 mm3 +/- 48.4 (+/-standard deviation) for the MRX-133 group, 45.4 mm3 +/- 24.9 for the perflutren protein-type A microsphere group, and 17.7 mm3 +/- 9.0 for the control group. In the MRX-133 group, the mean volume of coagulation necrosis was significantly greater than that of the control or the perflutren protein-type A microsphere group (P < .01), and in the perflutren protein-type A microsphere group, the volume of coagulation necrosis was greater than that of the control group (P < .05). MRX-133 had greater efficiency than perflutren protein-type A microspheres in high-intensity focused ultrasound-induced heating and coagulation of rabbit liver tissue.

Erythrocytes, as well as microbubble contrast agents, are important factors in improving thermal and therapeutic effects of high-intensity focused ultrasound

Erythrocytes, as well as microbubble contrast agents, are important factors in improving thermal effect of high-intensity focused ultrasound (US), or HIFU, and increasing the coagulation volume produced by HIFU irradiation. In vitro experiments used human plasma with various concentrations of human erythrocytes in combination with or without Levovist®. In vivo experiments used eight Japan white rabbits with three degrees of anemia. Using a 2.17-MHz transducer, HIFU was applied for 60 s, and the temperature rise and the volume of coagulation necrosis was evaluated. There was a significant correlation between the HIFU-induced temperature rise and hematocrit, with a correlation coefficient of 0.998 ( p = 0.0001). Although the temperature rise was smaller at low hematocrit, it was significantly increased by adding Levovist® in the suspension ( p < 0.01). The mean volume of coagulation necrosis was significantly greater in the rabbits with higher hematocrits ( p < 0.01), and that in the moderate anemia group was significantly increased by using Levovist® ( p < 0.01). (E-mail: ktakegami-tky@umin.ac.jp)

Percutaneous image-guided radiofrequency ablation in the therapeutic management of hepatocellular carcinoma

Owing to surveillance programs for detection of hepatocellular carcinoma (HCC) in patients with cirrhosis, more tumors are being detected at an early, asymptomatic stage. Percutaneous ablation is considered the best treatment option for patients with Child-Pugh class A or B cirrhosis and a single, nodular-type HCC smaller than 5 cm or as many as three HCC lesions, each smaller than 3 cm, when surgical resection or liver transplantation is not suitable. Radiofrequency ablation (RFA) has emerged as the most powerful method for percutaneous treatment of early-stage HCC. Recent studies have shown that RFA can achieve more effective local tumor control than ethanol injection and with fewer treatment sessions. In a randomized trial, local recurrence-free survival rates were significantly higher in patients who received RFA than in those treated by ethanol injection, and treatment allocation was confirmed as an independent prognostic factor by multivariate analysis. Due to advances in radiofrequency technology, RFA also has been used to treat patients with more advanced tumors. Preliminary reports have shown that RFA performed after balloon catheter occlusion of the hepatic artery, transarterial embolization, or chemoembolization results in increased volumes of coagulation necrosis, thus enabling successful destruction of large HCC lesions. This report reviews the current status of percutaneous, image-guided RFA in the therapeutic management of HCC.

Comparison between combination therapy of percutaneous ethanol injection and radiofrequency ablation and radiofrequency ablation alone for patients with hepatocellular carcinoma

In the present study, the characteristics of PEI-RFA treatment were further elucidated by analyzing the relationship between the volume of coagulated necrosis and the energy requirement for ablation or the amount of ethanol injected into HCC. The volume of coagulated necrosis, total energy requirement and energy requirement for coagulation of per unit volume were examined in the groups of PEI-RFA and RFA alone using the Cool-tip RF system. The results showed that the volume of coagulated necrosis induced was significantly larger in PEI-RFA group than in routine RFA group, when the total energy administered was comparable in both groups. In PEI-RFA, enlargement of coagulated necrosis was admitted in 3 dimensions and the amount of energy requirement per unit volume of coagulated necrosis was negatively correlated with the amount of ethanol injected into HCC. These results suggest that, compared to RFA alone, PEI-RFA enables to induce comparable coagulated necrosis with smaller energy requirement, and that PEI-RFA is likely to be less invasive than RFA alone irrespective of inducing enhanced coagulated necrosis. Thus, simple prior injection of ethanol may make RFA treatment more effective and less invasive for the treatment of patients with HCC.

Efficacy of combination therapies of percutaneous or laparoscopic ethanol-lipiodol injection and radiofrequency ablation

Percutaneous radiofrequency ablation (RFA) is able to destroy hepatocellular carcinoma (HCC) in a few sessions without major complications. We have previously shown that not only the combined use of percutaneous ethanol injection and RFA (PEI-RFA) but also injection of mixture of ethanol and lipiodol (PELIT) was useful for the treatment of HCC. In the present study, we further developed the combined use of PELIT and RFA through percutaneous or laparoscopic approach (PELI-RFA or LELI-RFA) and evaluated its usefulness. Nineteen nodules in 18 cases were treated with PELI-RFA or LELI-RFA. In the cases treated with LELI-RFA, no bleeding and no spilling milky fluid containing tumor cells were observed from the surface of ablated tumors. In the cases sufficiently treated with PELI-RFA or LELI-RFA, the mixture of ethanol and lipiodol was accumulated in the entire region of the tumor and low-density area was observed around the lipiodol deposit by computed tomography (CT). These delineations of coagulated area were helpful to evaluate the precise area of safety margin around the tumor treated with PELI-RFA or LELI-RFA. Furthermore, the total volume of coagulated necrosis significantly and positively correlated with the product of energy requirement for ablation and the volume of ethanol injected by PELI-RFA or LELI-RFA. Among the cases treated with PELI-RFA or LELI-RFA, local recurrence emerged only in one case in whom enough safety margin could not be achieved by PELI-RFA. Therefore, it is critical to evaluate whether enough safety margin could be obtained with RFA therapy, and PELI-RFA and LELI-RFA are helpful in visualizing the safety margin area.

Expression of heat shock proteins in human hepatocellular carcinoma after radiofrequency ablation in an animal model

Since tumor cells are known to express heat shock proteins (HSPs) as a response to cellular stress, such as heat, our goal was to determine the expression of HSPs in human hepatocellular carcinoma (HCC) before and after percutaneous radiofrequency (RF) ablation using a rat model. In 12 nude rats, human HCC cells (SK-HEP-1) were inoculated subcutaneously. A total of 21 tumors were grown in the bilateral flanks of the rats. Of those, 19 were treated with percutaneous RF ablation (diameter of RF electrode, 18 gauge; RF ablation energy, 60-600 W; duration, 20-100 sec). To determine the extent of necrosis, and the cellular expression of HSP 70 and HSP 90, the tumors were excised within 6, 12 and 24 h after RF ablation, respectively. The extent of the coagulation necrosis and the expression of HSP 70 and 90 were evaluated. Linear regression analysis showed a significant correlation between the volume of coagulation necrosis and the RF energy applied. Before RF ablation, expression of HSP 70 and 90 was 0% and 0-30%, respectively. Following RF ablation, the maximum level of HSP 70 expression was 60%, and the maximum level of HSP 90 expression was 100%. The expression of HSP 70 and 90 in HCC is significantly increased by RF ablation. These findings are of particular importance in the host-tumor immune response and might be useful in forthcoming immunotherapeutical strategies.

Radiofrequency Ablation of Lung Malignancies: Where Do We Stand?

Percutaneous radiofrequency (RF) ablation is a minimally invasive technique used to treat solid tumors. Because of its ability to produce large volumes of coagulation necrosis in a controlled fashion, this technique has gained acceptance as a viable therapeutic option for unresectable liver malignancies. Recently, investigation has been focused on the clinical application of RF ablation in the treatment of lung malignancies. In theory, lung tumors are well suited to RF ablation because the surrounding air in adjacent normal parenchyma provides an insulating effect, thus facilitating energy concentration within the tumor tissue. Experimental studies in rabbits have confirmed that lung RF ablation can be safely and effectively performed via a percutaneous, transthoracic approach, and have prompted the start of clinical investigation. Pilot clinical studies have shown that RF ablation enables successful treatment of relatively small lung malignancies with a high rate of complete response and acceptable morbidity, and have suggested that the technique could represent a viable alternate or complementary treatment method for patients with non-small cell lung cancer or lung metastases of favorable histotypes who are not candidates for surgical resection. This article gives an overview of lung RF ablation, discussing experimental animal findings, rationale for clinical application, technique and methodology, clinical results, and complications.

A microbubble agent improves the therapeutic efficiency of high intensity focused ultrasound: a rabbit kidney study.

Eighty kidneys (40 left and 40 right kidneys) of New Zealand rabbits were ablated using high intensity focused ultrasound (HIFU), (14,300 W/cm(2), 1.0 MHz). Kidneys were randomly divided into two groups. HIFU was performed in the manner of linear scan in both groups. Prior to HIFU, normal saline solution and isovolumetric microbubble agent were administrated intravenously in groups I and II, respectively. HIFU was finished in all left kidneys and in 26/40 right ones. The therapeutic efficiency was reflected using necrosis rate (cubic centimeters per second), which was the tissue volume of coagulative necrosis per 1 s HIFU exposure. In both groups, predetermined volumes were damaged without harming overlying tissues. Necrosis rates were increased in group II both in left (0.0089+/-0.0107 vs. 0.0493+/-0.0777, P=0.0323) and in right (0.0039+/-0.0055 vs. 0.0162+/-0.0168, P=0.0248) kidneys. Pathological examinations confirmed that there were no intact tissue focuses within exposed regions in either group. These findings suggested that the microbubble agent improved the therapeutic efficiency of HIFU. Hemorrhage and hyperemia were also detected on the margin of the ablated tissues (both in cortex and medulla) in both groups.

Percutaneous radiofrequency ablation therapy for patients with hepatocellular carcinoma during occlusion of hepatic blood flow. Comparison with standard percutaneous radiofrequency ablation therapy.

The therapeutic efficacy of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) is limited by the small volume of coagulation necrosis obtained at each activation of the RF system and the sometimes irregular burn shape due to the proximity of large vessels that have a cooling effect. To improve the efficacy of RFA, the authors designed RFA with balloon occlusion of the hepatic artery (balloon-occluded RFA). In this study, we investigated the efficacy of balloon-occluded RFA and compared the coagulation diameters obtained with balloon-occluded RFA and standard RFA. We retrospectively studied 31 patients with 42 HCC lesions measuring less than 4 cm in the greatest dimension. We performed balloon-occluded RFA for 12 patients (n = 15 nodules) and standard RFA for 19 patients (n = 27 nodules). Initial therapeutic efficacy was evaluated with dynamic computed tomography scan performed 2 weeks after one treatment. There were no significant differences in the ablation conditions such as the frequency of a fully expanded electrode, the number of needle insertions, application cycles, or treatment times between the two groups. However, the greatest dimension of the area coagulated by balloon-occluded RFA was significantly larger (greatest long-axis dimension, 36.6 +/- 3.8 mm; greatest short-axis dimension, 30.1 +/- 6.0 mm; n = 15 lesions) than that coagulated by standard RFA (greatest long-axis dimension, 26.7 +/- 6.4 mm; greatest short-axis dimension, 23.1 +/- 5.0 mm; n = 27 lesions; greatest long-axis dimension, P < 0.001; greatest short-axis dimension, P < 0.001). Balloon-occluded RFA is superior to standard RFA for the treatment of many hepatocellular lesions, especially when larger volumes of coagulation are required.

Optimizing the shape of ultrasound transducers for interstitial thermal ablation

Heat deposition by interstitial routes, especially with ultrasound-based instruments, is becoming a valuable therapeutic option for the treatments of sites, which are difficult to access from outside of the body. The active part of most interstitial ultrasound applicators described in the literature is logically tubular to induce cylindrical volumes of coagulation necrosis. Because the pressure generated by such tubular transducers falls off rapidly with radial distance, we previously proposed using a rotating plane transducer. For a plane wave, the pressure fall-off is only due to attenuation, which makes deeper lesions and shorter treatment times possible. This work represents an advance in the development of ultrasound applicators designed for interstitial applications. This new applicator used a rotating slightly focused transducer. A brief theoretical analysis resulted in the choice of a long focal distance of 22 mm to obtain a nearly constant pressure all along the therapeutic depth. To experimentally validate this focal distance, pressure measurements were made in a tissue mimicking liquid phantom and the results were compared with those obtained with a plane transducer. In vitro experiments showed that necrosis could be induced at a depth of 15 mm. In the same conditions, the greatest depth attained with a plane transducer was only 10 mm. Because each individual lesion is narrower, more lesions and more time are required to necrose a cylindrical volume. The main advantage of this new type of applicator is that it can be used to induce necrosis at a greater depth without varying either the frequency, the intensity or the transducer cooling efficiency.

Development of an interstitial ultrasound applicator for endoscopic procedures: animal experimentation

—Biliary cancer is very difficult to treat, mainly because of the advanced stage at which such tumours are detected and the low efficacy of systemic therapeutic modalities like radiotherapy. Palliative measures designed to clear the duct (either by means of surgery or an endoscopic procedure) are presently performed. A relatively noninvasive alternative could be developed to fill this gap in the therapeutic arsenal. To this end, we have designed an interstitial ultrasound (US) applicator suitable for use with a digestive endoscope. This applicator is based on a water-cooled plane transducer that operates at 10 MHz. Although, because the target zone is cylindrical in shape, it might have seemed more logical to use a cylindrical transducer. Nevertheless, a plane transducer was chosen because the pressure field from this kind of emitter decreases less quickly, which means faster and deeper heating. However, to generate coagulation necrosis all around the duct, the applicator has to be rotated around its axis; this is achieved by means of a flexible metallic shaft (2 m in length and 3.8 mm in diameter) that joins the device’s active head (which contains the transducer) to the casing with all the connectors. A holder is fixed at the endoscope channel inlet; it controls the rotation of the applicator. Trials were conducted on pigs. The duodenoscope was introduced via the oesophagus down through the duodenum as far as the hepatopancreatic ampulla. Using a guide wire, the applicator was navigated into the duct via the endoscope instrument channel. Well defined, reproducible volumes of coagulation necrosis with a diameter of 20 mm were generated in the biliary tissue and the liver. These promising results indicate that this kind of endoscopic US delivery system may represent an effective tool for the treatment of biliary tumours in humans. An Independent Ethics Committee recently approved preliminary clinical trials of this applicator.

Sonographisch gesteuerte perkutane Hochfrequenzthermotherapie von Lebertumoren mit perfundierten Nadelelektroden

Percutaneous radiofrequency ablation (HFTT) is a new therapeutic technique for the treatment of inoperable primary and secondary liver tumors. We report our initial experience using a newly developed perfusion electrode. Twelve liver tumors (11 metastases of colorectal tumors, 1 hepatocellular carcinoma) were treated in 5 inoperable patients. The patients had 1 to 3 liver tumors. All lesions were cytologically confirmed and measured 12-47 mm. The technique was approved by the institutional review board and informed consent was obtained from all patients. A 12-mm-needle electrode with a 15-mm-active tip was introduced into the liver tumors under ultrasound guidance and tumors were coagulated with radiofrequency energy of 350 kHz. The needle electrodes were perfused with 0.9% saline during coagulation to increase the volume of coagulation necrosis without tissue vaporization. The serial changes in tumor size after therapy were evaluated with spiral CT imaging. Dynamic CT showed that unenhanced areas indicative of coagulation necrosis developed in all tumors. In 8 of 12 tumors no signs of recurrence appeared during the observation period of 7 (5-12) months. No major complications were observed. Our preliminary experience suggests that percutaneous radiofrequency coagulation can be a simple, safe and potentially effective treatment for selected patients with inoperable liver tumors. The results justify further studies to investigate the possible role in clinical practice.

RADIO FREQUENCY ABLATION OF RENAL CELL CARCINOMA VIA IMAGE GUIDED NEEDLE ELECTRODES

No AccessJournal of UrologyClinical Urology: Case Reports1 Feb 1999RADIO FREQUENCY ABLATION OF RENAL CELL CARCINOMA VIA IMAGE GUIDED NEEDLE ELECTRODES FRANCIS J. McGOVERN, BRADFORD J. WOOD, S. NAHUM GOLDBERG, and PETER R. MUELLER FRANCIS J. McGOVERNFRANCIS J. McGOVERN More articles by this author , BRADFORD J. WOODBRADFORD J. WOOD More articles by this author , S. NAHUM GOLDBERGS. NAHUM GOLDBERG More articles by this author , and PETER R. MUELLERPETER R. MUELLER More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(01)61961-XAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "RADIO FREQUENCY ABLATION OF RENAL CELL CARCINOMA VIA IMAGE GUIDED NEEDLE ELECTRODES." The Journal of Urology, 161(2), pp. 599–600 References 1 : In situ ablation of focal hepatic neoplasms. In: . New York: Thieme Medical Pub.1997. Google Scholar 2 : Radiofrequency ablation of hepatic metastases with cooled-tip electrodes: results in 29 patients. Radiology1997; 205: 367. Google Scholar 3 : Radiofrequency interstitial tumor ablation (RITA) is a possible new modality for treatment of renal cancer: ex vivo and in vivo experience. J. Endourol.1997; 11: 251. Crossref, Medline, Google Scholar From the Departments of Urology and Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, and Department of Radiology, National Institutes of Health, Bethesda, Maryland© 1999 by American Urological Association, Inc.FiguresReferencesRelatedDetailsCited byKunkle D, Egleston B and Uzzo R (2008) Excise, Ablate or Observe: The Small Renal Mass Dilemma—A Meta-Analysis and ReviewJournal of Urology, VOL. 179, NO. 4, (1227-1234), Online publication date: 1-Apr-2008.JACOMIDES L, OGAN K, WATUMULL L and CADEDDU J (2018) Laparoscopic Application Of Radio Frequency Energy Enables In Situ Renal Tumor Ablation And Partial NephrectomyJournal of Urology, VOL. 169, NO. 1, (49-53), Online publication date: 1-Jan-2003.MATLAGA B, ZAGORIA R, WOODRUFF R, TORTI F and HALL M (2018) Phase II Trial of Radio Frequency Ablation of Renal Cancer: Evaluation of the Kill ZoneJournal of Urology, VOL. 168, NO. 6, (2401-2405), Online publication date: 1-Dec-2002.PAVLOVICH C, WALTHER M, CHOYKE P, PAUTLER S, CHANG R, LINEHAN W and WOOD B (2018) PERCUTANEOUS RADIO FREQUENCY ABLATION OF SMALL RENAL TUMORS: INITIAL RESULTSJournal of Urology, VOL. 167, NO. 1, (10-15), Online publication date: 1-Jan-2002.PANTUCK A, ZISMAN A and BELLDEGRUN A (2018) THE CHANGING NATURAL HISTORY OF RENAL CELL CARCINOMAJournal of Urology, VOL. 166, NO. 5, (1611-1623), Online publication date: 1-Nov-2001.Corwin T, Lindberg G, Traxer O, Gettman M, Smith T, Pearle M and Cadeddu J (2018) LAPAROSCOPIC RADIOFREQUENCY THERMAL ABLATION OF RENAL TISSUE WITH AND WITHOUT HILAR OCCLUSIONJournal of Urology, VOL. 166, NO. 1, (281-284), Online publication date: 1-Jul-2001. Volume 161Issue 2February 1999Page: 599-600 Advertisement Copyright & Permissions© 1999 by American Urological Association, Inc.MetricsAuthor Information FRANCIS J. McGOVERN More articles by this author BRADFORD J. WOOD More articles by this author S. NAHUM GOLDBERG More articles by this author PETER R. MUELLER More articles by this author Expand All Advertisement PDF downloadLoading ...

Internally cooled power laser for MR-guided interstitial laser-induced thermotherapy of liver lesions: initial clinical results.

To evaluate experimentally and clinically an internally cooled power laser system for percutaneous treatment of liver metastases, with magnetic resonance (MR) imaging guidance, to increase the volume of coagulative necrosis with single laser beam applications. The power laser system consisted of standard cannulation paraphernalia and a specially designed 7-F protective catheter for cooling the laser tip during treatment to avoid carbonization. A microdome laser beam applicator with a laser tip diameter of 0.95 mm kept the entire device as small as possible. After the unit was tested in 40 porcine livers, 532 laser beam applications (mean power, 27.5 W [range, 22.1-30.0 W]; mean application time, 19.8 minutes [range, 14-30 minutes]) were performed with MR guidance in 127 patients with 318 liver metastases. The safety of the procedure and the volume of induced necrosis were evaluated. In vitro, cuboid areas of coagulative necrosis with a mean greatest diameter of 4.3 cm +/- 0.5 (SD) were demonstrated after single applications. In vivo, MR thermometry allowed accurate demarcation of changes induced by heat, with a mean diameter of necrosis of 3.3 cm +/- 1.4. No carbonization or vaporization of tissue or damage of equipment occurred during treatment. This power laser system can increase the volume of laser-induced necrosis in liver metastases with a single application, thereby simplifying and accelerating the treatment of larger lesions.

Hepatic metastases: percutaneous radio-frequency ablation with cooled-tip electrodes.

To assess the feasibility and safety of using cooled-tip electrodes to increase the volume of coagulation necrosis obtained or reduce the number of treatment sessions necessary with percutaneous tumor radio-frequency (RF) ablation. Twenty-nine patients with 44 hepatic metastases (1.3-5.1 cm diameter) from colorectal (n = 22), gastric (n = 5), pancreatic (n = 1), or breast (n = 1) carcinoma were treated with RF ablation using cooled-tip, 18-gauge electrodes with 2-3 cm tip exposure. Each tumor was treated in one or two treatment sessions. Technical success, ablation of all visualized tumor, was achieved in 40 (91%) metastases. Findings at computed tomography (CT) and magnetic resonance (MR) imaging performed 3-6 months after treatment confirmed complete necrosis of the entire metastasis in 66%. Disease-free survival was 50% at 12 months and 33% at 18 months, with localized progression of disease in 34% of treated lesions. Overall survival was 100%, 94%, and 89% at 6, 12, and 18 months, respectively. Only one complication, self-limited hemorrhage, was seen. Use of cooled-tip electrodes was a safe and feasible adjunct for tumor RF ablation therapy that produced larger volumes of coagulation necrosis with fewer electrode insertions than is produced with other RF ablation techniques.

Radiofrequency tissue ablation: Increased lesion diameter with a perfusion electrode

We sought to induce large zones of coagulation necrosis using radiofrequency (RF) with perfusion electrodes and to define optimal parameters for this system. 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. 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. 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 lesions.