Ramón Sousa

Large hepatic ablation with bipolar saline-enhanced radiofrequency: an experimental study in in vivo porcine liver with a novel approach

SUMMARY BACKGROUND DATA Radiofrequency ablation (RFA) is a relatively new technology for the local destruction of liver tumors. Development of recent devices has enabled the creation of larger lesions. Nevertheless, treating liver tumors larger than 2.5 cm in diameter often requires multiple overlapping ablations to encompass the tumor and the surrounding healthy tissue rim with an increasing risk of local recurrence. MATERIAL AND METHODS RFA (480 kHz) of the liver using our method was undertaken on a total number of 15 healthy farm pigs with (Group B, n = 8) or without (Group A, n = 5) the Pringle maneuver via laparotomy. The pigs were followed and euthanized on the seventh day of the experiment. Livers were removed for histological assessment. Time of the procedure, impedance, current, power output, energy output, temperatures in the liver, central temperature of the animal, volume size of the lesion, and delivered energy per lesion volume were determined and compared among groups. Additionally a regularity ratio (RR) was determined by gross examination of the specimen and scored (0-3) taking into account regularity and predictability of the ablation with pathologic assessment. RESULTS With both methods, ellipsoid lesions were created between the two probes. In both groups tissue impedance fell with time (r = -0.47, P < 0.01 and r = -0.34, P < 0.05, in Groups A and B, respectively). The mean lesion size achieved with the Pringle maneuver was the largest lesion size described in the literature for any RFA method in vivo and was greater in Group B than in Group A (123.22 cm(3) +/- 49.62 and 52.40 cm(3) +/- 23.59, respectively, P < 0.05). A better regularity and predictability evaluated by RR was observed in Group B compared to Group A (1.88 +/- 1.35 and 0.40 +/- 0.55, respectively, P < 0.05). Five major complications were described and attributed primarily to failure in isolation from hypertermic lesions. CONCLUSIONS Our new bipolar saline-enhanced electrode with Pringle maneuver achieves large hepatic ablations in in vivo pig liver. These large lesions are well-tolerated by the animal when thermal injuries to adjacent structures are avoided.

Musculoskeletal hydatid disease: A report of 13 cases

This is a retrospective study of 13 patients with muscular hydatidosis - i.e., 4% of the 309 cases of hydatid disease treated in our department during 1983-1999. The commonest clinical finding was an asymptomatic and slowly growing mass (7). Puncture or incision of the mass was followed by an infection of the cystic cavity with fistulization in 2 patients. The immunological findings were false negative in 4 patients. MR images were obtained in 4 patients before diagnosis, and were highly suggetive of hydatid disease. The cystic cavities in all 9 patients subjected to radical surgery healed without chemotherapy. Radical surgery was not possible in 4 cases, in 3 of whom the sacrum was involved. Medical treatment of these patients did not eliminate the disease and new operations were necessary.

Research and development of a new RF-assisted device for bloodless rapid transection of the liver: Computational modeling and in vivo experiments

BackgroundEfficient and safe transection of biological tissue in liver surgery is strongly dependent on the ability to address both parenchymal division and hemostasis simultaneously. In addition to the conventional clamp crushing or finger fracture methods other techniques based on radiofrequency (RF) currents have been extensively employed to reduce intraoperative blood loss. In this paper we present our broad research plan for a new RF-assisted device for bloodless, rapid resection of the liver.MethodsOur research plan includes computer modeling and in vivo studies. Computer modeling was based on the Finite Element Method (FEM) and allowed us to estimate the distribution of electrical power deposited in the tissue, along with assessing the effect of the characteristics of the device on the temperature profiles. Studies based on in vivo pig liver models provided a comparison of the performance of the new device with other techniques (saline-linked technology) currently employed in clinical practice. Finally, the plan includes a pilot clinical trial, in which both the new device and the accessory equipment are seen to comply with all safety requirements.ResultsThe FEM results showed a high electrical gradient around the tip of the blade, responsible for the maximal increase of temperature at that point, where temperature reached 100°C in only 3.85 s. Other hot points with lower temperatures were located at the proximal edge of the device. Additional simulations with an electrically insulated blade produced more uniform and larger lesions (assessed as the 55°C isotherm) than the electrically conducting blade. The in vivo study, in turn, showed greater transection speed (3 ± 0 and 3 ± 1 cm2/min for the new device in the open and laparoscopic approaches respectively) and also lower blood loss (70 ± 74 and 26 ± 34 mL) during transection of the liver, as compared to saline-linked technology (2 ± 1 cm2/min with P = 0.002, and 527 ± 273 mL with P = 0.001).ConclusionA new RF-assisted device for bloodless, rapid liver resection was designed, built and tested. The results demonstrate the potential advantages of this device over others currently employed.

Improved perfusion system for bipolar radiofrequency ablation of liver: preliminary findings from a computer modeling study

Current systems for radiofrequency ablation of liver tumors are unable to consistently treat tumors larger than 3 cm in diameter with a single electrode in a single application. One of the strategies for enlarging coagulation zone dimensions is to infuse saline solutions into the tissue through the active electrodes. Nevertheless, the uncontrolled and undirected diffusion of boiling saline into the tissue has been associated with irregular coagulation zones and severe complications, mainly due to reflux of saline along the electrode path. In order to improve the perfusion bipolar ablation method, we hypothesized that the creation of small monopolar coagulation zones adjacent to the bipolar electrodes and previous to the saline infusion would create preferential paths for the saline to concentrate on the targeted coagulation zone. Firstly, we conducted ex vivo experiments in order to characterize the monopolar coagulation zones. We observed that they are practically impermeable to the infused saline. On the basis of this finding, we built theoretical models and conducted computer simulations to assess the feasibility of our hypothesis. Temperature distributions during bipolar ablations with and without previous monopolar coagulation zones were obtained. The results showed that in the case of monopolar coagulation zones the temperature of the tissue took longer to reach 100 degrees C. Since this temperature value is related to rise of impedance, and the time necessary for this process is directly related to the volume of the coagulation zone, our results suggest that monopolar sealing would allow larger coagulation zones to be created. Future experimental studies should confirm this benefit.

RF tumor ablation with internally cooled electrodes and saline infusion: what is the optimal location of the saline infusion?

BackgroundRadiofrequency ablation (RFA) of tumors by means of internally cooled electrodes (ICE) combined with interstitial infusion of saline may improve clinical results. To date, infusion has been conducted through outlets placed on the surface of the cooled electrode. However, the effect of infusion at a distance from the electrode surface is unknown. Our aim was to assess the effect of perfusion distance (PD) on the coagulation geometry and deposited power during RFA using ICE.MethodsExperiments were performed on excised bovine livers. Perfusion distance (PD) was defined as the shortest distance between the infusion outlet and the surface of the ICE. We considered three values of PD: 0, 2 and 4 mm. Two sets of experiments were considered: 1) 15 ablations of 10 minutes (n ≥ 4 for each PD), in order to evaluate the effect of PD on volume and diameters of coagulation; and 2) 20 additional ablations of 20 minutes. The effect of PD on deposited power and relative frequency of uncontrolled impedance rises (roll-off) was evaluated using the results from the two sets of experiments (n ≥ 7 for each PD). Comparisons between PD were performed by analysis of variance or Kruskal-Wallis test. Additionally, non-linear regression models were performed to elucidate the best PD in terms of coagulation volume and diameter, and the occurrence of uncontrolled impedance rises.ResultsThe best-fit least square functions were always obtained with quadratic curves where volume and diameters of coagulation were maximum for a PD of 2 mm. A thirty per cent increase in volume coagulation was observed for this PD value compared to other values (P < 0.05). Likewise, the short coagulation diameter was nearly twenty five per cent larger for a 2 mm PD than for 0 mm. Regarding deposited power, the best-fit least square function was obtained by a quadratic curve with a 2 mm PD peak. This matched well with the higher relative frequency of uncontrolled impedance rises for PD of 0 and 4 mm.ConclusionSaline perfusion at around 2 mm from the electrode surface while using an ICE in RFA improves deposition of energy and enlarges coagulation volume.

Results of a pilot trial of immunotherapy with dendritic cells pulsed with autologous tumor lysates in patients with advanced cancer.

Aims and background The purpose of the study was to test the immunological and clinical effects of infusions of dendritic cells pulsed with autologous tumor lysate in patients with advanced cancer. Patients and methods Peripheral blood mononuclear cells from 15 patients with metastatic cancer (melanoma in 10, lung cancer in 2, renal cell carcinoma in 1, sarcoma in 1, breast cancer in 1) were harvested by leukapheresis after mobilization with GM-CSF (5 μg/kg/day s.c. for 4 days). Mononuclear cells were separated and cultured in GM-CSF (1000 U/ml) and interleukin-4 (1000 U/ml) for 7 days. Phenotype was assessed by 2-color flow cytometry and immunocytochemistry. On day 6, dendritic cells were pulsed with 1 g of fresh autologous tumor lysate for 24 h and infused intravenously. Interleukin-2 (6 million IU), interferon a (4 million IU) and GM-CSF (400 μg) were injected s.c. daily for 10 days beginning on the day of dendritic cell infusion. Treatment was repeated every 21 days for 3 courses. Results The morphology, immunocytochemistry and phenotype of cultured cells was consistent with dendritic cells: intense positivity for HLA-DR and CD86, with negativity for markers of other lineages, including CD3, CD4, CD8 and CD14. More than 5 × 107 dendritic cells were injected in all patients. Nine patients developed >5 mm delayed type cutaneous hypersensitivity reactions to tumor lysate ± GM-CSF after the first immunization (larger than GM-CSF in all cases). Median delayed type cutaneous hypersensitivity to lysate + GM-CSF was 3 cm after the third immunization. One melanoma patient with skin, liver, lung and bone metastases had a partial response lasting 8 months (followed by progression in the brain). Seven patients had stable disease for >3 months, and 7 had progression. Conclusions Infusion of tumor lysate-pulsed dendritic cells induces a strong cell-mediated antitumor immune reaction in patients with advanced cancer and has some clinical activity.

Cirugía mamaria mínimamente invasiva: reconstrucción mamaria mediante colgajo muscular puro del gran dorsal

Resumen Introduccion Las tecnicas minimamente invasivas se han extendido a todos los campos de la cirugia, la cirugia mamaria es quiza la cirugia que mas se deberia beneficiar de estos conceptos, por sus caracteristicas especiales, reduce la agresion quirurgica y elimina u oculta cicatrices. El proposito de nuestro trabajo es presentar una nueva tecnica quirurgica para la reseccion de grandes volumenes de tejido mamario, incluida la mastectomia subcutanea completa, y reconstruccion mediante un colgajo del musculo gran dorsal con o sin material protesico, a traves de una minima incision cutanea. Pacientes y metodo Analisis retrospectivo de nuestra serie de 5 casos clinicos intervenidos con esta tecnica, que nos ha permitido ponerla a punto y establecer las indicaciones. Analizamos los detalles tecnicos, las complicaciones y los resultados. Resultados Hemos intervenido a 5 pacientes mediante esta tecnica quirurgica (1 con hamartoma gigante, 1 con carcinoma in situ multicentrico con enfermedad de Paget, 1 con tumor mamario maligno multicentrico y 2 con tumoraciones malignas unicas de cuadrantes externos) practicando resecciones oncologicas suficientes (2 resecciones parciales mamarias y 3 mastectomias subcutaneas) e incluian biopsia de ganglio centinela o linfadenectomia axilar completa. Tras un periodo de seguimiento medio de 10 meses no ha habido recidivas locales y el resultado estetico es excelente. Conclusiones La tecnica minimamente invasiva, a traves de una incision vertical en linea axilar posterior, permite realizar una reseccion mamaria parcial o completa, asi como una reconstruccion inmediata mediante tejido autologo o material protesico.

Premature roll-off in radiofrequency ablation using bipolar saline-enhanced electrodes

Sir, We have read with interest the article by Lee et al. [1]. The authors tried to compare two radiofrequency bipolar systems: the Berchtold system with open-perfused electrodes (bipolar saline-enhanced electrodes) and the Radionics system with cooled-wet electrodes in bipolar mode. We would like to congratulate the authors for their experimental design and excellent results. However, the work raises some concerns. First of all, the accumulated energy output was 87,555.1±86,787 Ws (joules) for the open-perfused electrode group when the maximum power output for the generator was 60 W for 20 min (that means a maximum energy output of 72,000 Ws per experience). Furthermore, the huge variability expressed by the standard deviation in output energy deposition means that in some cases, less than 1,000 Ws were deposited, while in other cases more than two times the maximum output energy was employed. Actually, on the basis of the authors’ explanation, the main reason for the reduced ablation dimension in the open-perfused group compared with the cooled-wet group is the premature rise of the impedance over 700 Ω. This premature roll-off of the impedance is related to the more intense desiccation and charring of the tissues in a bipolar mode compared with the monopolar configuration caused by a higher current deposition in the small amount of tissue interposed between the electrodes, when no diversion of the heat occurs. We agree with this latest statement, and in our experiences we adapted the power to the global distance to the electrodes in order to keep the impedance low, as is also discussed in [2]. For example, for a 7-cm distance of the electrodes, we employ advantageously less than 40 W with more perfusion of saline for an in vivo application in a similar configuration [3], whereas Lee et al. employ 60 W for only a 3-cm separation between the electrodes with less perfusion of saline. The power algorithm the authors uses is usually employed for a monopolar configuration when more diversion of heat occurs, but in a bipolar setting one may overheat the tissue prematurely. This can account for the premature roll-off in the authors’ open-perfused group and for their suboptimal employ of an open-perfused electrode. Secondly, in the authors’ bipolar configuration the electrodes must be placed parallel, as we previously considered and abandoned [4, 5], because, as the authors state, the insertion of both electrodes encompassing the tumor could be difficult. In the actual configuration we have integrated both electrodes in one needle, making electrode placement more accurate and safe [3]. Lee et al. state that one of the axes of the coagulation area we created An author’s reply to this letter is available at http://dx.doi.org/10.1007/s00330-005-2650-z.

Lymphoscintigraphic SPECT/CT Localization of a Sentinel Node in an Unusual Position: Rotterʼs Node

A 57-year-old woman with infiltrating ductal carcinoma of the right breast underwent lymph node scintigraphy with Tc-99m-nanocolloid for preoperative sentinel node localization. On planar images, an unusual pattern of lymphatic drainage was observed. We performed a chest SPECT/CT, revealing an interpectoral sentinel node, ie, Rotters node. The patient underwent radioguided surgery and the sentinel node was located intraoperatively, and found to be disease-free. SPECT/CT fusion techniques have enhanced precision in locating sentinel nodes, enabling the surgeon to shorten surgical times.

Small ablation zones created previous to saline infusion result in enlargement of the coagulated area during perfusion RF ablation: an ex vivo experimental study.

One of the strategies for enlarging coagulation zone dimensions during RF ablation of liver tumours is to infuse saline solutions into the tissue during ablation. The aim of this study was to evaluate experimentally whether the creation of a small coagulation adjacent to a bipolar RF applicator and prior to perfused RF ablation would allow enlargement of the coagulation zone. Thirty bipolar RF ablations (group A, n = 15; group B, n = 15) were performed in excised bovine livers. Additionally, in group B a monopolar RF application (60 W, 20 s) was performed before bipolar ablation using three small additional electrodes. Electrical parameters and dimensions of the ablation zone were compared between groups. Despite the fact that all three ablation zone diameters were greater in group B, only one of the minor diameters was significantly longer (5.52 +/- 0.66 cm versus 4.87 +/- 0.47 cm). Likewise, volume was significantly bigger in group B (100.26 +/- 24.10 cm(3) versus 79.56 +/- 15.59 cm(3)). There were no differences in the impedance evolution, allowing a relatively high constant power in both groups (around 90 W). The efficacy of delivering energy (expressed as the delivered energy per coagulation volume) was significantly better in group B, showing a lower value (578 J cm(-3) versus 752 J cm(-3)). These results suggest that the creation of small ablation zones prior to saline infusion improves the performance of this perfusion system, and hence the total volume.