Sample records for ablation technique possibilities

  1. Global ablation techniques.

    PubMed

    Woods, Sarah; Taylor, Betsy

    2013-12-01

    Global endometrial ablation techniques are a relatively new surgical technology for the treatment of heavy menstrual bleeding that can now be used even in an outpatient clinic setting. A comparison of global ablation versus earlier ablation technologies notes no significant differences in success rates and some improvement in patient satisfaction. The advantages of the newer global endometrial ablation systems include less operative time, improved recovery time, and decreased anesthetic risk. Ablation procedures performed in an outpatient surgical or clinic setting provide advantages both of potential cost savings for patients and the health care system and improved patient convenience. Copyright © 2013. Published by Elsevier Inc.

  2. Radiofrequency ablation for hepatocellular carcinoma: assistant techniques for difficult cases.

    PubMed

    Inoue, Tatsuo; Minami, Yasunori; Chung, Hobyung; Hayaishi, Sousuke; Ueda, Taisuke; Tatsumi, Chie; Takita, Masahiro; Kitai, Satoshi; Hatanaka, Kinuyo; Ishikawa, Emi; Yada, Norihisa; Hagiwara, Satoru; Ueshima, Kazuomi; Kudo, Masatoshi

    2010-07-01

    To confirm the safety and effectiveness of techniques to assist radiofrequency ablation (RFA) for difficult cases, we retrospectively evaluated successful treatment rates, early complications and local tumor progressions. Between June 1999 and April 2009, a total of 341 patients with 535 nodules were treated as difficult cases. Artificial pleural effusion assisted ablation was performed on 64 patients with 82 nodules. Artificial ascites-assisted ablation was performed on 11 patients with 13 nodules. Cooling by endoscopic nasobiliary drainage (ENBD) tube-assisted ablation was performed on 6 patients with 8 nodules. When the tumors were not well visualized with conventional B-mode ultrasonography (US), contrast-enhanced US-assisted ablation with Levovist or Sonazoid or virtual CT sonography-assisted ablation was performed. Contrast-enhanced US-assisted ablation was performed on 139 patients with 224 nodules and virtual CT sonography-assisted ablation was performed on 121 patients with 209 nodules. In total, complete ablation was achieved in 514 of 535 (96%) nodules in difficult cases. For RFA with artificial pleural effusion, artificial ascites and ENBD, complete response was confirmed in all cases. For contrast-enhanced US- and CT sonography-assisted ablation, complete response was 95%. Early complications were recognized in 24 cases (4.5%). All cases recovered with no invasive treatment. Local tumor recurrence was investigated in 377 nodules of 245 patients, and 69 (18%) nodules were positive. Tumor recurrences in each assisted technique were 14.7% in artificial pleural effusion cases, 7% in artificial ascites, 12.5% in ENBD tube cases, 31% in virtual CT sonography, and 8.5% in contrast-enhanced US. Although local tumor progression needs to be carefully monitored, assisted techniques of RFA for difficult cases are well tolerated and expand the indications of RFA. Copyright (c) 2010 S. Karger AG, Basel.

  3. [Percutaneous radiofrequency ablation of osteoid osteomas: technique and results].

    PubMed

    Bruners, P; Penzkofer, T; Günther, R W; Mahnken, A

    2009-08-01

    Osteoid osteoma is a benign primary bone tumor that typically occurs in children and young adults. Besides local pain, which is often worse at night, prompt relief due to medication with acetylsalicylic acid (ASS) is characteristic for this bone lesion. Because long-term medication with ASS does not represent an alternative treatment strategy due to its potentially severe side effects, different minimally invasive image-guided techniques for the therapy of osteoid osteoma have been developed. In this context radiofrequency (RF) ablation in particular has become part of the clinical routine. The technique and results of image-guided RF ablation are compared to alternative treatment strategies. Using this technique, an often needle-shaped RF applicator is percutaneously placed into the tumor under image guidance. Then a high-frequency alternating current is applied by the tip of the applicator which leads to ionic motion within the tissue resulting in local heat development and thus in thermal destruction of the surrounding tissue including the tumor. The published primary and secondary success rates of this technique are 87 and 83 %, respectively. Surgical resection and open curettage show comparable success rates but are associated with higher complication rates. In addition image-guided RF ablation of osteoid osteomas is associated with low costs. In conclusion image-guided RF ablation can be considered the gold standard for the treatment of osteoid osteoma.

  4. Atrial fibrillation ablation using cryoballoon technology: Recent advances and practical techniques.

    PubMed

    Chen, Shaojie; Schmidt, Boris; Bordignon, Stefano; Bologna, Fabrizio; Perrotta, Laura; Nagase, Takahiko; Chun, K R Julian

    2018-04-16

    Atrial fibrillation (AF) affects 1-2% of the population, and its prevalence is estimated to double in the next 50 years as the population ages. AF results in impaired patients' life quality, deteriorated cardiac function, and even increased mortality. Antiarrhythmic drugs frequently fail to restore sinus rhythm. Catheter ablation is a valuable treatment approach for AF, even as a first-line therapy strategy in selected patients. Effective electrical pulmonary vein isolation (PVI) is the cornerstone of all AF ablation strategies. Use of radiofrequency (RF) catheter in combination of a three-dimensional electroanatomical mapping system is the most established ablation approach. However, catheter ablation of AF is challenging even sometimes for experienced operators. To facilitate catheter ablation of AF without compromising the durability of the pulmonary vein isolation, "single shot" ablation devices have been developed; of them, cryoballoon ablation, is by far the most widely investigated. In this report, we review the current knowledge of AF and discuss the recent evidence in catheter ablation of AF, particularly cryoballoon ablation. Moreover, we review relevant data from the literature as well as our own experience and summarize the key procedural practical techniques in PVI using cryoballoon technology, aiming to shorten the learning curve of the ablation technique and to contribute further to reduction of the disease burden. © 2018 Wiley Periodicals, Inc.

  5. [Percutaneous ablation of metastases: where are we and new techniques].

    PubMed

    Palussière, Jean; Buy, Xavier; Fonck, Mariane

    2013-04-01

    When a metastatic disease is localized and slowly evolving either spontaneously or after a general treatment, a local treatment may be proposed. For about 15 years, image-guided percutaneous ablation has been developed which allows to treat tumors with temperature modifications. These mini-invasive techniques may be repeated in patients whose disease may be chronic. Ablation techniques are also used in a more palliative manner on bone metastases to obtain pain relief.

  6. In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gerasimova, N.; Dziarzhytski, S.; Weigelt, H.

    2013-06-15

    In situ focus characterization is demonstrated by working at an extreme ultraviolet (XUV) free-electron laser source using ablation technique. Design of the instrument reported here allows reaching a few micrometres resolution along with keeping the ultrahigh vacuum conditions and ensures high-contrast visibility of ablative imprints on optically transparent samples, e.g., PMMA. This enables on-line monitoring of the beam profile changes and thus makes possible in situ alignment of the XUV focusing optics. A good agreement between focal characterizations retrieved from in situ inspection of ablative imprints contours and from well-established accurate ex situ analysis with Nomarski microscope has been observedmore » for a typical micro-focus experiment.« less

  7. Possible role for cryoballoon ablation of right atrial appendage tachycardia when conventional ablation fails.

    PubMed

    Amasyali, Basri; Kilic, Ayhan

    2015-06-01

    Focal atrial tachycardia arising from the right atrial appendage usually responds well to radiofrequency ablation; however, successful ablation in this anatomic region can be challenging. Surgical excision of the right atrial appendage has sometimes been necessary to eliminate the tachycardia and prevent or reverse the resultant cardiomyopathy. We report the case of a 48-year-old man who had right atrial appendage tachycardia resistant to multiple attempts at ablation with use of conventional radiofrequency energy guided by means of a 3-dimensional mapping system. The condition led to cardiomyopathy in 3 months. The arrhythmia was successfully ablated with use of a 28-mm cryoballoon catheter that had originally been developed for catheter ablation of paroxysmal atrial fibrillation. To our knowledge, this is the first report of cryoballoon ablation without isolation of the right atrial appendage. It might also be an alternative to epicardial ablation or surgery when refractory atrial tachycardia originates from the right atrial appendage.

  8. Contemporary Tools and Techniques for Substrate Ablation of Ventricular Tachycardia in Structural Heart Disease.

    PubMed

    Hutchinson, Mathew D; Garza, Hyon-He K

    2018-02-24

    As we have witnessed in other arenas of catheter-based therapeutics, ventricular tachycardia (VT) ablation has become increasingly anatomical in its execution. Multi-modality imaging provides anatomical detail in substrate characterization, which is often complex in nonischemic cardiomyopathy patients. Patients with intramural, intraseptal, and epicardial substrates provide challenges in delivering effective ablation to the critical arrhythmia substrate due to the depth of origin or the presence of adjacent critical structures. Novel ablation techniques such as simultaneous unipolar or bipolar ablation can be useful to achieve greater lesion depth, though at the expense of increasing collateral damage. Disruptive technologies like stereotactic radioablation may provide a tailored approach to these complex patients while minimizing procedural risk. Substrate ablation is a cornerstone of the contemporary VT ablation procedure, and recent data suggest that it is as effective and more efficient that conventional activation guided ablation. A number of specific targets and techniques for substrate ablation have been described, and all have shown a fairly high success in achieving their acute procedural endpoint. Substrate ablation also provides a novel and reproducible procedural endpoint, which may add predictive value for VT recurrence beyond conventional programmed stimulation. Extrapolation of outcome data to nonischemic phenotypes requires caution given both the variability in substrate nonischemic distribution and the underrepresentation of these patients in previous trials.

  9. Dual 8-plate technique is not as effective as ablation for epiphysiodesis about the knee.

    PubMed

    Stewart, Daniel; Cheema, Asad; Szalay, Elizabeth A

    2013-12-01

    Lower extremity length inequality can be problematic in children and is often addressed surgically. Several techniques have traditionally been utilized for epiphysiodesis, the goal being physeal ablation. Recently, 8-plates, initially developed for hemiepiphysiodesis, have been extended to epiphysiodesis by placing the plates on both medial and lateral sides of the physis. No prior studies have compared 8-plates with physeal ablation techniques. Between January 2003 and August 2009, 27 patients underwent epiphysiodesis surgery using either physeal ablation or 8-plate technique. Sixteen patients had physeal ablation and 11 had dual 8-plates. A retrospective chart review sought demographic data, outcomes, and complications. Radiographs were reviewed to measure pretreatment and posttreatment limb lengths. The median improvement in limb length discrepancy was 15.5 mm in the physeal ablation group and 4 mm in the 8-plate group (P<0.001). This difference was maintained following linear regression factoring out the effect of time (10.78 mm for ablation vs. 5.62 mm for 8-plates; P=0.016). There was no statistically significant difference in complication rate between the groups (P=0.112). Our study demonstrated physeal ablation to be a significantly superior treatment compared with dual 8-plates for epiphysiodesis. Despite theoretical advantages of 8-plates to perform epiphysiodesis about the knee, this study does not recommend the use of medial and lateral 8-plates to effect epiphysiodesis. Therapeutic III.

  10. [Catheter ablation in patients with refractory cardiac arrhythmias with radiofrequency techniques].

    PubMed

    de Paola, A A; Balbão, C E; Silva Netto, O; Mendonça, A; Villacorta, H; Vattimo, A C; Souza, I A; Guiguer Júnior, N; Portugal, O P; Martinez Filho, E E

    1993-02-01

    evaluate the efficacy of radiofrequency catheter ablation in patients with refractory cardiac arrhythmias. twenty patients with refractory cardiac arrhythmias were undertaken to electrophysiologic studies for diagnosis and radiofrequency catheter ablation of their reentrant arrhythmias. Ten patients were men and 10 women with ages varying from 13 to 76 years (mean = 42.4 years). Nineteen patients had supraventricular tachyarrhythmias: One patient had atrial tachycardia and 1 atrial fibrillation with rapid ventricular rate, 5 patients had reentrant nodal tachycardia, 12 patients had reentrant atrioventricular tachycardia and 1 patient had right ventricular outflow tract tachycardia. the mean time of the procedure was 4.1 hours. The radiofrequency current energy applied was 40-50 V for 30-40 seconds. Ablation was successful in 18/20 (90%) patients; in 15/18 (83%) of successfully treated patients the same study was done for diagnosis and radiofrequency ablation. One patient had femoral arterial occlusion and was treated with no significant sequelae. During a mean follow-up of 4 months no preexcitation or reentrant tachycardia occurred. the results of our experience with radiofrequency catheter ablation of cardiac arrhythmias suggest that this technique can benefit an important number of patients with cardiac arrhythmias.

  11. Optical ablation/temperature gage (COTA)

    NASA Astrophysics Data System (ADS)

    Cassaing, J.; Balageas, D.

    ONERA has ground and flight tested for heat-shield recession a novel technique, different from current radiation and acoustic measurement methods. It uses a combined ablation/temperature gage that views the radiation optically from a cavity embedded within the heat shield. Flight measurements, both of temperature and of passage of the ablation front, are compared with data generated by a predictive numerical code. The ablation and heat diffusion into the instrumented ablator can be simulated numerically to evaluate accurately the errors due to the presence of the gage. This technology was established in 1978 and finally adopted after ground tests in arc heater facilities. After four years of flight evaluations, it is possible to evaluate and criticize the sensor reliability.

  12. Thyroid Radiofrequency Ablation: Updates on Innovative Devices and Techniques

    PubMed Central

    Park, Hye Sun; Park, Auh Whan; Chung, Sae Rom; Choi, Young Jun; Lee, Jeong Hyun

    2017-01-01

    Radiofrequency ablation (RFA) is a well-known, effective, and safe method for treating benign thyroid nodules and recurrent thyroid cancers. Thyroid-dedicated devices and basic techniques for thyroid RFA were introduced by the Korean Society of Thyroid Radiology (KSThR) in 2012. Thyroid RFA has now been adopted worldwide, with subsequent advances in devices and techniques. To optimize the treatment efficacy and patient safety, understanding the basic and advanced RFA techniques and selecting the optimal treatment strategy are critical. The goal of this review is to therefore provide updates and analysis of current devices and advanced techniques for RFA treatment of benign thyroid nodules and recurrent thyroid cancers. PMID:28670156

  13. Microwave Ablation (MWA): Basics, Technique and Results in Primary and Metastatic Liver Neoplasms - Review Article.

    PubMed

    Vogl, Thomas J; Nour-Eldin, Nour-Eldin A; Hammerstingl, Renate Maria; Panahi, Bita; Naguib, Nagy N N

    2017-11-01

    Purpose  The locoregional interventional oncological treatment approach is an accepted modality for liver neoplasms, especially for hepatocellular carcinoma (HCC) and oligonodular liver metastases. Materials and Methods  The main aim of ablation therapies like microwave ablation (MWA) is to eradicate all malignant cells in a minimally invasive technique under imaging guidance while preserving the healthy tissue with a sufficient safety margin (at least 5 mm) surrounding the ablated lesion. Results  Ablation therapy can be performed via a percutaneous, laparoscopic or intraoperative approach under ultrasound, MRI or CT guidance for adequate localization and monitoring of the ablation process. Conclusion  Ablation is the method of choice for oligonodular HCCs ≤ 3 cm. The technical success rate varies from 88 % to 98 % and progression-free survival (PFS) at 3 years from 27 % to 91.7 %. The same criteria apply to the therapy of liver metastases. Key Points   · Careful selection of patients proves to be essential for optimum results of MWA. · Interventionists should be familiar with all aspects of complication and rapid assessment of imaging methods in order to evaluate induced damage by thermal ablation. · MWA seems to have some advantages over radiofrequency ablation, like shorter ablation time, less pain, less heat sink effect; however, scientific proof is needed. Citation Format · Vogl TJ, Nour-Eldin A, Hammerstingl RM et al. Microwave Ablation (MWA): Basics, Technique and Results in Primary and Metastatic Liver Neoplasms - Review Article. Fortschr Röntgenstr 2017; 189: 1055 - 1066. © Georg Thieme Verlag KG Stuttgart · New York.

  14. Laser-induced thermotherapy: an in-situ ablation technique for the local treatment of irresectable colorectal liver metastases

    NASA Astrophysics Data System (ADS)

    Ritz, Joerg-Peter; Isbert, Christoph M.; Roggan, Andre; Wacker, Frank; Buhr, Heinz-Johannes; Germer, Christoph-Thomas

    2000-11-01

    Laser-induced thermotherapy (LITT) is a so called in-situ- ablation technique which is used for the treatment of liver tumors. Coagulation necrosis is induced by transmitting the laser irradiation via quartz fibers directly into the tumor tissue. LITT represents similarly to surgical liver resection a local treatment form for liver metastases. The Nd-YAG laser (1064 nm) was used. The application system was placed percutaneously under open MRI control. On-line monitoring was done with MRI for evaluation of the postoperative follow-up we performed MRI-controls every 3 months. A total of 20 patients were treated. Due to the irradiation plan performed preoperatively, the treated tumors could be completely ablated by hyperthermia in all procedures. Complications were pleural effusion in 7 patients and a bile fistula and subcapsulary liver hematoma in one patient each. Local control of tumor growth can be achieved in tumors having undergone complete hyperthermic ablation. An assessment of the method regarding a prognostic benefit is not yet possible due to the short follow-up period and the small patient population.

  15. Fractional CO2 resurfacing: has it replaced ablative resurfacing techniques?

    PubMed

    Duplechain, Jesse Kevin

    2013-05-01

    The author uses the pulsed ablative CO2 laser regularly for skin rejuvenation. This decision is based on the gold standard status of the CO2 modality and an innovative aftercare treatment shown in the author's practice to greatly reduce the complications of ablative pulsed CO2 laser treatment. Depending on the patient and the severity of the skin condition, the author customizes each treatment, which may also include fractional CO2 lasers, fat grafting, facelifting, or any combination of these techniques. This article presents a detailed description of the evolution of skin rejuvenation with lasers and the current role of lasers as an adjunct to face and necklift surgery. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Comparative evaluation of diode laser ablation and surgical stripping technique for gingival depigmentation: A clinical and immunohistochemical study.

    PubMed

    Bakutra, Gaurav; Shankarapillai, Rajesh; Mathur, Lalit; Manohar, Balaji

    2017-01-01

    There are various treatment modalities to remove the black patches of melanin pigmentation. The aim of the study is to clinically compare the diode laser ablation and surgical stripping technique for gingival depigmentation and to evaluate their effect on the histological changes in melanocyte activity. A total of 40 sites of 20 patients with bilateral melanin hyperpigmentation were treated with the surgical stripping and diode laser ablation technique. Change in Hedin index score, change in area of pigmentation using image analyzing software, pain perception, patient preference of treatment were recorded. All 40 sites were selected for immunohistochemical analysis using HMB-45 immunohistochemical marker. At 12 months post-operative visit, in all sites, repigmentation was observed with different grades of Hedin index. Paired t -test, analysis of variance, and Chi-square tests were used for statistical analysis. Repigmentation in surgical stripping is significantly lesser compared to laser ablation. Lesser numbers of melanocytes were found on immunohistological examination at 12 months postoperatively. Comparison for patient preference and pain indices give statistically significant values for diode laser techniques. Gingival hyperpigmentation is effectively managed by diode laser ablation technique and surgical stripping method. In this study, surgical stripping technique found to be better compared to diode laser ablation.

  17. Comparative evaluation of diode laser ablation and surgical stripping technique for gingival depigmentation: A clinical and immunohistochemical study

    PubMed Central

    Bakutra, Gaurav; Shankarapillai, Rajesh; Mathur, Lalit; Manohar, Balaji

    2017-01-01

    Introduction: There are various treatment modalities to remove the black patches of melanin pigmentation. The aim of the study is to clinically compare the diode laser ablation and surgical stripping technique for gingival depigmentation and to evaluate their effect on the histological changes in melanocyte activity. Materials and Methods: A total of 40 sites of 20 patients with bilateral melanin hyperpigmentation were treated with the surgical stripping and diode laser ablation technique. Change in Hedin index score, change in area of pigmentation using image analyzing software, pain perception, patient preference of treatment were recorded. All 40 sites were selected for immunohistochemical analysis using HMB-45 immunohistochemical marker. Results: At 12 months post-operative visit, in all sites, repigmentation was observed with different grades of Hedin index. Paired t-test, analysis of variance, and Chi-square tests were used for statistical analysis. Repigmentation in surgical stripping is significantly lesser compared to laser ablation. Lesser numbers of melanocytes were found on immunohistological examination at 12 months postoperatively. Comparison for patient preference and pain indices give statistically significant values for diode laser techniques. Conclusion: Gingival hyperpigmentation is effectively managed by diode laser ablation technique and surgical stripping method. In this study, surgical stripping technique found to be better compared to diode laser ablation. PMID:28539864

  18. Benign thyroid nodule unresponsive to radiofrequency ablation treated with laser ablation: a case report.

    PubMed

    Oddo, Silvia; Balestra, Margherita; Vera, Lara; Giusti, Massimo

    2018-05-11

    Radiofrequency ablation and laser ablation are safe and effective techniques for reducing thyroid nodule volume, neck symptoms, and cosmetic complaints. Therapeutic success is defined as a nodule reduction > 50% between 6 and 12 months after the procedure, but a percentage of nodules inexplicably do not respond to thermal ablation. We describe the case of a young Caucasian woman with a solid benign thyroid nodule who refused surgery and who had undergone radiofrequency ablation in 2013. The nodule did not respond in terms of either volume reduction or improvement in neck symptoms. After 2 years, given the patient's continued refusal of thyroidectomy, we proposed laser ablation. The nodule displayed a significant volume reduction (- 50% from radiofrequency ablation baseline volume, - 57% from laser ablation baseline), and the patient reported a significant improvement in neck symptoms (from 6/10 to 1/10 on a visual analogue scale). We conjecture that some benign thyroid nodules may be intrinsically resistant to necrosis when one specific ablation technique is used, but may respond to another technique. To the best of our knowledge, this is the first description of the effect of performing a different percutaneous ablation technique in a nodule that does not respond to radiofrequency ablation.

  19. TECHNIQUES AND OUTCOMES OF MINIMALLY-INVASIVE TRABECULAR ABLATION AND BYPASS SURGERY

    PubMed Central

    Kaplowitz, Kevin; Schuman, Joel S.; Loewen, Nils A.

    2014-01-01

    Minimally invasive glaucoma surgeries (MIGS) can improve the conventional, pressure dependent outflow by bypassing or ablating the trabecular meshwork or create alternative drainage routes into the suprachoroidal or subconjunctival space. They have a highly favorable risk profile compared to penetrating surgeries and lower intraocular pressure with variable efficacy that may depend on the extent of outflow segments accessed. Since they are highly standardized procedures that use clear corneal incisions, they can elegantly be combined with cataract and refractive procedures to improve vision in the same session. There is a growing need for surgeons to become proficient in MIGS to address the increasing prevalence of glaucoma and cataracts in a well-informed, aging population. Techniques of visualization and instrumentation in an anatomically highly confined space with semi-transparent tissues are fundamentally different from other anterior segment surgeries and present even experienced surgeons with a substantial learning curve. Here, we provide practical tips and review techniques and outcomes of TM bypass and ablation MIGS. PMID:24338085

  20. Percutaneous ablation of pancreatic cancer

    PubMed Central

    D’Onofrio, Mirko; Ciaravino, Valentina; De Robertis, Riccardo; Barbi, Emilio; Salvia, Roberto; Girelli, Roberto; Paiella, Salvatore; Gasparini, Camilla; Cardobi, Nicolò; Bassi, Claudio

    2016-01-01

    Pancreatic ductal adenocarcinoma is a highly aggressive tumor with an overall 5-year survival rate of less than 5%. Prognosis and treatment depend on whether the tumor is resectable or not, which mostly depends on how quickly the diagnosis is made. Chemotherapy and radiotherapy can be both used in cases of non-resectable pancreatic cancer. In cases of pancreatic neoplasm that is locally advanced, non-resectable, but non-metastatic, it is possible to apply percutaneous treatments that are able to induce tumor cytoreduction. The aim of this article will be to describe the multiple currently available treatment techniques (radiofrequency ablation, microwave ablation, cryoablation, and irreversible electroporation), their results, and their possible complications, with the aid of a literature review. PMID:27956791

  1. Slow pathway radiofrequency ablation in patients with AVNRT: junctional rhythm is less frequent during magnetic navigation ablation than with the conventional technique.

    PubMed

    Ricard, Philippe; Latcu, Decebal Gabriel; Yaïci, Khelil; Zarqane, Naima; Saoudi, Nadir

    2010-01-01

    The occurrence of accelerated junctional rhythm (JR) during radiofrequency ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT) is frequent. The aim of the present study was to compare the occurrence of JR during magnetic remote catheter ablation to the conventional manual ablation. Twenty six patients (males: seven; age: 51 + or - 15 years) underwent slow pathway ablation with magnetic navigation (MN) system (Niobe, Stereotaxis Inc., St. Louis, MO, USA) and were compared to a control group of 11 patients (males: three; age: 53 + or - 16 years) treated with conventional manual ablation. A 4-mm nonirrigated tip catheter was used in both groups with a maximum of 30 W and 60 degrees C. Acute success was obtained in all patients. In the MN group, three patients out of 24 had no junctional beat (JB) at all and seven patients had 10 or less JB. In contrast, in the conventional group no patient had less than 10 JB. The mean number of JB in the MN group was 66 + or - 94.9 (0-410) and 200 + or - 243.1 (43-914) in the control group (P = 0.019). In the MN group one patient had a first-degree atrioventricular block. No other complication occurred. Magnetic remote catheter ablation of AVNRT is effective and is associated with less JB than the manual conventional technique. Therefore, JB may not be considered as a mandatory indicator for successful AVNRT ablation with MN system.

  2. A novel technique for orchiectomy and scrotal ablation in the sugar glider (Petaurus breviceps).

    PubMed

    Morges, Michelle A; Grant, Krystan R; MacPhail, Catriona M; Johnston, Matthew S

    2009-03-01

    In this report, we describe a simple, safe, and efficacious technique for orchiectomy and scrotal ablation with the use of a carbon dioxide light amplification by stimulated emission of radiation (laser) in sugar gliders (Petaurus breviceps). The study population included nine sugar gliders, ages 2-24 mo, presented for orchiectomy. After induction of general anesthesia, orchiectomy and scrotal ablation were performed by severing the scrotal stalk with the laser. All sugar gliders were discharged the same day. Mean anesthesia time was 6.09 +/- 0.94 min. Mean surgery time was 15.11 +/- 8.39 sec, and mean recovery time was 4.11 +/- 3.60 min. With an outlier removed, mean recovery time was 2.95 +/- 1.03 min. No serious postoperative surgical complications were observed. The technique described is a simple procedure with rapid surgical and recovery times that has the potential to become the standard procedure for orchiectomy and scrotal ablation in sugar gliders.

  3. Long-term outcomes of the current remote magnetic catheter navigation technique for ablation of atrial fibrillation.

    PubMed

    Yuan, Shiwen; Holmqvist, Fredrik; Kongstad, Ole; Jensen, Steen M; Wang, Lingwei; Ljungström, Erik; Hertervig, Eva; Borgquist, Rasmus

    2017-12-01

    Comparisons between remote magnetic (RMN) and manual catheter navigation for atrial fibrillation (AF) ablation have earlier been reported with controversial results. However, these reports were based on earlier generations of the RMN system. To evaluate the outcomes of the most current RMN system for AF ablation in a larger patient population with longer follow-up time, 112 patients with AF (78 paroxysmal, 34 persistent) who underwent AF ablation utilizing RMN (RMN group) were compared to 102 AF ablation patients (72 paroxysmal, 30 persistent) utilizing manual technique (Manual group). The RMN group was associated with significantly shorter fluoroscopy time (10.4 ± 6.4 vs. 16.3 ± 10.9 min, p < .001) but used more RF energy (64.1 ± 19.4KJ vs. 54.3 ± 24.1 KJ, p < .05), while total procedure time showed no significant difference (201 ± 35 vs. 196 ± 44 min, NS). After 39 ± 9/44 ± 10 months of follow-up, AF-free rates at 1year, 2 years and 3.5 years post ablation were 63%, 46% and 42% in the RMN group vs. 60%, 32% and 30% (survival analysis p < .05) in the Manual group, whereas clinically effective rates were 82%, 73% and 70% for the former vs. 70%, 56% and 49% for the latter (survival analysis p < .005). Differing from previous reports, our data from a larger patient population and longer follow-up time demonstrates that compared to manual technique, the most current RMN technique is associated with better procedural and clinical outcomes for AF ablation.

  4. Effect of nonparallel placement of in-circle bipolar radiofrequency ablation probes on volume of tissue ablated with heat sink.

    PubMed

    Pillai, Krishna; Al-Alem, Ihssan; Akhter, Javed; Chua, Terence C; Shehata, Mena; Morris, David L

    2015-06-01

    Percutaneous bipolar radiofrequency ablation (RFA) is a minimally invasive technique for treating liver tumors. It is not always possible to insert the bipolar probes parallel to each other on either side of tumor, since it restricts maneuverability away from vital structures or ablate certain tumor shape. Therefore, we investigated how nonparallel placement of probes affected ablation. Bipolar RFA in parallel and in divergent positions were submerged in tissue model (800 mL egg white) at 37°C and ablated. Temperature probes, T1 and T2 were placed 8.00 mm below the tip of the probes, T3 in between the probe coil elements and T4 and T5 at water inlet and outlet, respectively. Both models with heat sink (+HS) and without (-HS) were investigated. The mean ablated tissue volume, mass, density and height increased linearly with unit angle increase for -HS model. With +HS, a smaller increase in mean volume and mass, a slightly greater increase in mean density but a reduction in height of tissue was seen. The mean ablation time and duration of maximum temperature with +HS was slightly larger, compared with -HS, while -HS ablated at a slightly higher temperature. The heat sink present was minimal for probes in parallel position compared to nonparallel positions. Divergence from parallel insertion of bipolar RFA probes increased the mean volume, mass, and density of tissue ablated. However, the presence of large heat sinks may limit the application of this technique, when tumors border on larger vessels. © The Author(s) 2014.

  5. Aggregation effect on absorbance spectrum of laser ablated gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Isnaeni; Irmaniar; Herbani, Y.

    2017-04-01

    Plasmon of gold nanoparticles is one of the hot topics nowadays due to various possible applications. The application is determined by plasmon peak in absorbance spectrum. We have fabricated gold nanoparticles using laser ablation technique and studied the influence of CTAB (Cetyl trimethylammonium bromide) effect on the optical characterization of fabricated gold nanoparticles. We ablated a gold plate using NdYAG pulsed laser at 1064 nm wavelength, 10 Hz pulse frequency at low energy density. We found there are two distinctive plasmon peaks, i.e., primary and secondary peaks, where the secondary peak is the main interests of this work. Our simulation results have revealed that the secondary plasmon peak is affected by random aggregation of gold nanoparticles. Our research leads to good techniques on fabrication of colloidal gold nanoparticles in aqueous solution using laser ablation technique.

  6. Microgroove fabrication with excimer laser ablation techniques for optical fiber array alignment purposes

    NASA Astrophysics Data System (ADS)

    Naessens, Kris; Van Hove, An; Coosemans, Thierry; Verstuyft, Steven; Vanwassenhove, Luc; Van Daele, Peter; Baets, Roel G.

    2000-11-01

    Currently, an ever increasing need for bandwidth, compactness and efficiency characterizes the world of interconnect and data communication. This tendency has already led to serial links being gradually replaced by parallel optical interconnect solutions. However, as the maximum capacity for the latter will be reached in the near future, new approaches are required to meet demand. One possible option is to switch to 2D parallel implementations of fiber arrays. In this paper we present the fabrication of a 2D connector for coupling a 4x8 array of plastic optical fibers to RCLED or VCSEL arrays. The connector consists primarily of dedicated PMMA plates in which arrays of 8 precisely dimensioned grooves at a pitch of 250 micrometers are introduced. The trenches are each 127 micrometers deep and their width is optimized to allow fixation of plastic optical fibers. We used excimer laser ablation for prototype fabrication of these alignment microstructures. In a later stage, the plates can be replicated using standard molding techniques. The laser ablation technique is extremely well suited for rapid prototyping and proves to be a versatile process yielding high accuracy dimensioning and repeatability of features in a wide diversity of materials. The dependency of the performance in terms of quality of the trenches (bottom roughness) and wall angle on various parameters (wavelength, energy density, pulse frequency and substrate material) is discussed. The fabricated polymer sheets with grooves are used to hold optical fibers by means of a UV-curable adhesive. In a final phase, the plates are stacked and glued in order to realize the 2D-connector of plastic optical fibers for short distance optical interconnects.

  7. The Effect of Atrial Fibrillation Ablation Techniques on P Wave Duration and P Wave Dispersion.

    PubMed

    Furniss, Guy O; Panagopoulos, Dimitrios; Kanoun, Sadeek; Davies, Edward J; Tomlinson, David R; Haywood, Guy A

    2018-02-14

    A reduction in surface electrocardiogram (ECG) P wave duration and dispersion is associated with improved outcomes in atrial fibrillation ablation. We investigated the effects of different ablation strategies on P wave duration and dispersion, hypothesising that extensive left atrial (LA) ablation with left atrial posterior wall isolation would give a greater reduction in P wave duration than more limited ablation techniques. A retrospective analysis of ECGs from patients who have undergone atrial fibrillation (AF) ablation was performed and pre-procedural sinus rhythm ECGs were compared with the post procedure ECGs. Maximal P wave duration was measured in leads I or II, minimum P wave duration in any lead and values were calculated for P wave duration and dispersion. Left atrial dimensions and medications at the time of ECG were documented. Ablation strategies compared were; pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) and the persistent AF (PsAF) ablation strategies of pulmonary vein isolation plus additional linear lesions (Lines), left atrial posterior wall isolation via catheter (PWI) and left atrial posterior wall isolation via staged surgical and catheter ablation (Hybrid). Sixty-nine patients' ECGs were analysed: 19 PVI, 21 Lines, 14 PWI, 15 Hybrid. Little correlation was seen between pre-procedure left atrial size and P wave duration (r=0.24) but LA size and P wave duration was larger in PsAF patients. A significant difference was seen in P wave reduction driven by Hybrid AF ablation (p<0.005) and Lines (<0.02). There was no difference amongst P wave dispersion between groups but the largest reduction was seen in the Hybrid ablation group. P wave duration increased with duration of continuous atrial fibrillation. Hybrid AF ablation significantly reduced P wave duration and dispersion compared to other ablation strategies including posterior wall isolation via catheter despite this being the same lesion set. Copyright © 2018

  8. [Radiofrequency ablation of hepatocellular carcinoma].

    PubMed

    Widmann, Gerlig; Schullian, Peter; Bale, Reto

    2013-03-01

    Percutaneous radiofrequency ablation (RFA) is well established in the treatment of hepatocellular carcinoma (HCC). Due to its curative potential, it is the method of choice for non resectable BCLC (Barcelona Liver Clinic) 0 and A. RFA challenges surgical resection for small HCC and is the method of choice in bridging for transplantation and recurrence after resection or transplantation. The technical feasibility of RFA depends on the size and location of the HCC and the availability of ablation techniques (one needle techniques, multi-needle techniques). More recently, stereotactic multi-needle techniques with 3D trajectory planning and guided needle placement substantially improve the spectrum of treatable lesions including large volume tumors. Treatment success depends on the realization of ablations with large intentional margins of tumor free tissue (A0 ablation in analogy to R0 resection), which has to be documented by fusion of post- with pre-ablation images, and confirmed during follow-up imaging.

  9. Transgenic Reproductive Cell Ablation.

    PubMed

    Lawit, Shai J; Chamberlin, Mark A

    2017-01-01

    Numerous cell ablation technologies are available and have been used in reproductive tissues, particularly for male tissues and cells. The importance of ablation of reproductive tissues is toward a fundamental understanding reproductive tissue development and fertilization, as well as, in developing sterility lines important to breeding strategies. Here, we describe techniques for developing ablation lines for both male and female reproductive cells. Also discussed are techniques for analysis, quality control, maintenance, and the lessening of pleiotropism in such lines.

  10. Assessment of laser ablation techniques in a-si technologies for position-sensor development

    NASA Astrophysics Data System (ADS)

    Molpeceres, C.; Lauzurica, S.; Ocana, J. L.; Gandia, J. J.; Urbina, L.; Carabe, J.

    2005-07-01

    Laser micromachining of semiconductor and Transparent Conductive Oxides (TCO) materials is very important for the practical applications in photovoltaic industry. In particular, a problem of controlled ablation of those materials with minimum of debris and small heat affected zone is one of the most vital for the successful implementation of laser micromachining. In particular, selective ablation of thin films for the development of new photovoltaic panels and sensoring devices based on amorphous silicon (a-Si) is an emerging field, in which laser micromachining systems appear as appropriate tools for process development and device fabrication. In particular, a promising application is the development of purely photovoltaic position sensors. Standard p-i-n or Schottky configurations using Transparent Conductive Oxides (TCO), a-Si and metals are especially well suited for these applications, appearing selective laser ablation as an ideal process for controlled material patterning and isolation. In this work a detailed study of laser ablation of a widely used TCO, Indium-tin-oxide (ITO), and a-Si thin films of different thicknesses is presented, with special emphasis on the morphological analysis of the generated grooves. The profiles of ablated grooves have been studied in order to determine the best processing conditions, i.e. laser pulse energy and wavelength, and to asses this technology as potentially competitive to standard photolithographic processes. The encouraging results obtained, with well defined ablation grooves having thicknesses in the order of 10 μm both in ITO and a-Si, open up the possibility of developing a high-performance double Schottky photovoltaic matrix position sensor.

  11. The sound of dental tissue ablation as a possible parameter for conservative dentistry

    NASA Astrophysics Data System (ADS)

    Robles, Fábio Renato P.; Mendes, Fausto Medeiros; Matos, Adriana Bona

    2007-02-01

    Studies in cariology have been struggling for the development of caries prevention techniques, precocious diagnoses of lesions, re-mineralization of incipient carious lesions and early restorative intervention with minimally invasive procedures. When removing caries, healthy dental structure is often removed inadvertently during its final phase, for being quite difficult to precise the limits between viable and decayed dental tissues clinically. With laser technologies, a subjective clinical hint, often used to indicate when tissue ablation should be stopped is that different sounds are perceptive whether in carious (bass) or in healthy (treble) dental structure; when sound produced by ablation turned treble it would mean that healthy tissue was reached. This study aims to classify those audio differences and to turn them into objective parameters for a conservative operative dentistry with minimally invasive tissue removal when using erbium lasers. Twenty freshly extracted human teeth were used (10 decayed and 10 sound teeth). Dentine was erbium laser irradiated under same parameters, distance and refrigeration and a mono directional microphone was set 10 cm far from the operative area in order to capture and record the ablation produced sounds when working either on carious or healthy dentine. Ten pulses per file were then analysed in a computer software (200 analyses). It was permitted to draw similarities among the patterns in each group (decayed and healthy teeth) as well as differences between decayed and healthy produced sounds. Audio analysis came out to be a technical reliable objective parameter to determine whether laser ablated dentine substrates are decayed or sound; therefore it can be proposed as a conservative parameter, avoiding unnecessary removal of healthy dentine and restricting it to carious one.

  12. Substrate-Mediated Laser Ablation under Ambient Conditions for Spatially-Resolved Tissue Proteomics

    PubMed Central

    Fatou, Benoit; Wisztorski, Maxence; Focsa, Cristian; Salzet, Michel; Ziskind, Michael; Fournier, Isabelle

    2015-01-01

    Numerous applications of ambient Mass Spectrometry (MS) have been demonstrated over the past decade. They promoted the emergence of various micro-sampling techniques such as Laser Ablation/Droplet Capture (LADC). LADC consists in the ablation of analytes from a surface and their subsequent capture in a solvent droplet which can then be analyzed by MS. LADC is thus generally performed in the UV or IR range, using a wavelength at which analytes or the matrix absorb. In this work, we explore the potential of visible range LADC (532 nm) as a micro-sampling technology for large-scale proteomics analyses. We demonstrate that biomolecule analyses using 532 nm LADC are possible, despite the low absorbance of biomolecules at this wavelength. This is due to the preponderance of an indirect substrate-mediated ablation mechanism at low laser energy which contrasts with the conventional direct ablation driven by sample absorption. Using our custom LADC system and taking advantage of this substrate-mediated ablation mechanism, we were able to perform large-scale proteomic analyses of micro-sampled tissue sections and demonstrated the possible identification of proteins with relevant biological functions. Consequently, the 532 nm LADC technique offers a new tool for biological and clinical applications. PMID:26674367

  13. Cartilage ablation studies using mid-IR free electron laser

    NASA Astrophysics Data System (ADS)

    Youn, Jong-In; Peavy, George M.; Venugopalan, Vasan

    2005-04-01

    The ablation rate of articular cartilage and fibrocartilage (meniscus), were quantified to examine wavelength and tissue-composition dependence of ablation efficiency for selected mid-infrared wavelengths. The wavelengths tested were 2.9 um (water dominant absorption), 6.1 (protein and water absorption) and 6.45 um (protein dominant absorption) generated by the Free Electron Laser (FEL) at Vanderbilt University. The measurement of tissue mass removal using a microbalance during laser ablation was conducted to determine the ablation rates of cartilage. The technique can be accurate over methods such as profilometer and histology sectioning where tissue surface and the crater morphology may be affected by tissue processing. The ablation efficiency was found to be dependent upon the wavelength. Both articular cartilage and meniscus (fibrocartilage) ablations at 6.1 um were more efficient than those at the other wavelengths evaluated. We observed the lowest ablation efficiency of both types of cartilage with the 6.45 um wavelength, possibly due to the reduction in water absorption at this wavelength in comparison to the other wavelengths that were evaluated.

  14. MR-guided microwave ablation in hepatic tumours: initial results in clinical routine.

    PubMed

    Hoffmann, Rüdiger; Rempp, Hansjörg; Keßler, David-Emanuel; Weiß, Jakob; Pereira, Philippe L; Nikolaou, Konstantin; Clasen, Stephan

    2017-04-01

    Evaluation of the technical success, patient safety and technical effectiveness of magnetic resonance (MR)-guided microwave ablation of hepatic malignancies. Institutional review board approval and informed patient consent were obtained. Fifteen patients (59.8 years ± 9.5) with 18 hepatic malignancies (7 hepatocellular carcinomas, 11 metastases) underwent MR-guided microwave ablation using a 1.5-T MR system. Mean tumour size was 15.4 mm ± 7.7 (7-37 mm). Technical success and ablation zone diameters were assessed by post-ablative MR imaging. Technique effectiveness was assessed after 1 month. Complications were classified according to the Common Terminology Criteria for Adverse Events (CTCAE). Mean follow-up was 5.8 months ± 2.6 (1-10 months). Technical success and technique effectiveness were achieved in all lesions. Lesions were treated using 2.5 ± 1.2 applicator positions. Mean energy and ablation duration per tumour were 37.6 kJ ± 21.7 (9-87 kJ) and 24.7 min ± 11.1 (7-49 min), respectively. Coagulation zone short- and long-axis diameters were 31.5 mm ± 10.5 (16-65 mm) and 52.7 mm ± 15.4 (27-94 mm), respectively. Two CTCAE-2-complications occurred (pneumothorax, pleural effusion). Seven patients developed new tumour manifestations in the untreated liver. Local tumour progression was not observed. Microwave ablation is feasible under near real-time MR guidance and provides effective treatment of hepatic malignancies in one session. • Planning, applicator placement and therapy monitoring are possible without using contrast enhancement • Energy transmission from the generator to the scanner room is safely possible • MR-guided microwave ablation provides effective treatment of hepatic malignancies in one session • Therapy monitoring is possible without applicator retraction from the ablation site.

  15. Influence of ablation wavelength and time on optical properties of laser ablated carbon dots

    NASA Astrophysics Data System (ADS)

    Isnaeni, Hanna, M. Yusrul; Pambudi, A. A.; Murdaka, F. H.

    2017-01-01

    Carbon dots, which are unique and applicable materials, have been produced using many techniques. In this work, we have fabricated carbon dots made of coconut fiber using laser ablation technique. The purpose of this work is to evaluate two ablation parameters, which are ablation wavelength and ablation time. We used pulsed laser from Nd:YAG laser with emit wavelength at 355 nm, 532 nm and 1064 nm. We varied ablation time one hour and two hours. Photoluminescence and time-resolved photoluminescence setup were used to study the optical properties of fabricated carbon dots. In general, fabricated carbon dots emit bluish green color emission upon excitation by blue laser. We found that carbon dots fabricated using 1064 nm laser produced the highest carbon dots emission among other samples. The peak wavelength of carbon dots emission is between 495 nm until 505 nm, which gives bluish green color emission. Two hours fabricated carbon dots gave four times higher emission than one hour fabricated carbon dot. More emission intensity of carbon dots means more carbon dots nanoparticles were fabricated during laser ablation process. In addition, we also measured electron dynamics of carbon dots using time-resolved photoluminescence. We found that sample with higher emission has longer electron decay time. Our finding gives optimum condition of carbon dots fabrication from coconut fiber using laser ablation technique. Moreover, fabricated carbon dots are non-toxic nanoparticles that can be applied for health, bio-tagging and medical applications.

  16. Radiofrequency ablation of the pancreas: protective effect of local cooling techniques.

    PubMed

    Geranios, Angelos; Pikoulis, Emmanouil; Papalois, Apostolos; Kontos, Michael; Agrogiannis, George; Petrou, Athanasios; Pavlakis, Emmanuel; Felekouras, Evangelos

    2015-05-01

    Pancreatic carcinoma is one of the commonest malignant diseases today and the majority of patients are suitable for palliative treatment only. Radiofrequency ablation (RFA) has been used extensively for the treatment of solid organ tumors but little is known on the efficacy and safety of pancreatic ablation. To further investigate the safety of pancreatic RFA, 18 pigs had RFA of the pancreas, close to superior mesenteric vein and duodenum. Group A (nine animals) was protected with peripancreatic cool perfusion and Group B (nine animals) with portal vein (PV) intravenous injection of cool saline. Biochemical and histological evidence suggested lateral thermal injury of the duodenal wall and superior mesenteric vein and acute pancreatitis in most animals. However, clinically and at autopsy, Group B animals fared much better. PV thrombosis, hepatic abscess, duodenal perforation, ascites, and extensive pancreatic necrosis were observed in Group A but not in Group B. The present study suggests that PV cool saline perfusion can prevent major complications caused by pancreatic RFA and may be used in combination with other protective techniques in the clinical setting to reduce RFA-associated morbidity.

  17. Endometrial ablation: normal appearance and complications.

    PubMed

    Drylewicz, Monica R; Robinson, Kathryn; Siegel, Cary Lynn

    2018-03-14

    Global endometrial ablation is a commonly performed, minimally invasive technique aimed at improving/resolving abnormal uterine bleeding and menorrhagia in women. As non-resectoscopic techniques have come into existence, endometrial ablation performance continues to increase due to accessibility and decreased requirements for operating room time and advanced technical training. The increased utilization of this method translates into increased imaging of patients who have undergone the procedure. An understanding of the expected imaging appearances of endometrial ablation using different modalities is important for the abdominal radiologist. In addition, the frequent usage of the technique naturally comes with complications requiring appropriate imaging work-up. We review the expected appearance of the post-endometrial ablated uterus on multiple imaging modalities and demonstrate the more common and rare complications seen in the immediate post-procedural time period and remotely.

  18. Ablation mass features in multi-pulses femtosecond laser ablate molybdenum target

    NASA Astrophysics Data System (ADS)

    Zhao, Dongye; Gierse, Niels; Wegner, Julian; Pretzler, Georg; Oelmann, Jannis; Brezinsek, Sebastijan; Liang, Yunfeng; Neubauer, Olaf; Rasinski, Marcin; Linsmeier, Christian; Ding, Hongbin

    2018-03-01

    In this study, the ablation mass features related to reflectivity of bulk Molybdenum (Mo) were investigated by a Ti: Sa 6 fs laser pulse at central wavelength 790 nm. The ablated mass removal was determined using Confocal Microscopy (CM) technique. The surface reflectivity was calibrated and measured by a Lambda 950 spectrophotometer as well as a CCD camera during laser ablation. The ablation mass loss per pulse increase with the increasing of laser shots, meanwhile the surface reflectivity decrease. The multi-pulses (100 shots) ablation threshold of Mo was determined to be 0.15 J/cm2. The incubation coefficient was estimated as 0.835. The reflectivity change of the Mo target surface following multi-pulses laser ablation were studied as a function of laser ablation shots at various laser fluences from 1.07 J/cm2 to 36.23 J/cm2. The results of measured reflectivity indicate that surface reflectivity of Mo target has a significant decline in the first 3-laser pulses at the various fluences. These results are important for developing a quantitative analysis model for laser induced ablation and laser induced breakdown spectroscopy for the first wall diagnosis of EAST tokamak.

  19. Bipolar radiofrequency ablation of benign thyroid nodules using a multiple overlapping shot technique in a 3-month follow-up.

    PubMed

    Kohlhase, Konstantin David; Korkusuz, Yücel; Gröner, Daniel; Erbelding, Christian; Happel, Christian; Luboldt, Wolfgang; Grünwald, Frank

    2016-08-01

    Purpose The aim of this study was to evaluate the decrease of benign thyroid nodules after bipolar radiofrequency ablation (RFA) in a 3-month follow-up using a multiple overlapping shot technique ('MOST'). Methods A total of 18 patients with 20 symptomatic benign thyroid nodules (17 cold nodules, 3 hyperfunctioning nodules) were treated in one single session by bipolar RFA. Bipolar ablation was performed using MOST. The nodule volumes were measured prior to ablation and 3 months after the procedure using ultrasound. The population consisted of either solid (>80% solid tissue within the volume of interest), complex, or cystic nodules (<20% solid tissue within the volume of interest). Results Bipolar RFA resulted in a highly significant (p < 0.0001) decrease of nodule volume (ΔV), median 5.3 mL (range 0.13-43.1 mL), corresponding to a relative reduction in mean of 56 ± 17.9%. Median initial volume was 8 mL (range 0.48-62 mL); 3 months after ablation a median volume of 2.3 mL (range 0.3-32 mL) was measured. Nodule growth ≥50% occurred in 70% (14 nodules). At the follow-up no complications such as infections, persisting pain, nerve injuries or immunogen stimulation occurred. Patients with cold nodules (15) remained euthyroid, with hyperfunctioning nodules either euthyroid (2) or latent hypofunctional (1). Conclusion The use of bipolar RFA is an effective, safe and suitable thermoablative technique to treat benign thyroid nodules. Combined with the multiple overlapping shot technique it allows sufficient ablation.

  20. Fabrication of microgrooves with excimer laser ablation techniques for plastic optical fiber array alignment purposes

    NASA Astrophysics Data System (ADS)

    Naessens, Kris; Van Hove, An; Coosemans, Thierry; Verstuyft, Steven; Ottevaere, Heidi; Vanwassenhove, Luc; Van Daele, Peter; Baets, Roel G.

    2000-06-01

    Laser ablation is extremely well suited for rapid prototyping and proves to be a versatile technique delivering high accuracy dimensioning and repeatability of features in a wide diversity of materials. In this paper, we present laser ablation as a fabrication method for micro machining in of arrays consisting of precisely dimensioned U-grooves in dedicated polycarbonate and polymethylmetacrylate plates. The dependency of the performance on various parameters is discussed. The fabricated plates are used to hold optical fibers by means of a UV-curable adhesive. Stacking and gluing of the plates allows the assembly of a 2D connector of plastic optical fibers for short distance optical interconnects.

  1. Persistent Atrial Fibrillation Ablation using the Tip-Versatile Ablation Catheter.

    PubMed

    Davies, Edward J; Clayton, Ben; Lines, Ian; Haywood, Guy A

    2016-07-01

    The mechanisms by which persistent atrial fibrillation (PsAF) develops are incompletely understood. Consequently, the optimal strategy for the ablative management of PsAF remains debated. Current methods are often time consuming, complex and non-reproducible. We assessed the Tip-Versatile Ablation Catheter (T-VAC) technique, a rapidly delivered, empirical technique based on the box-set concept using duty-cycled linear catheter ablation technology. Forty-four procedures in 40 patients undergoing PsAF ablation with the novel technique were prospectively entered onto a database: 27 de novo. Primary endpoint was freedom from arrhythmia at over two-year follow-up. Secondary endpoints were time to first arrhythmia recurrence, freedom from atrial fibrillation (AF) on and off antiarrhythmic drugs (AAD), procedural and fluoroscopy duration and complication rate. At mean follow-up of 33 months, absolute freedom from arrhythmia recurrence was 45% in the de novo group. Overall, at 33 (IQR 24-63) months, 60% of de novo patients were in sustained normal sinus rhythm and a further 15% reported only occasional paroxysms of AF at long-term follow-up. Procedure time was 192±25 mins, total energy delivered 2239±883s and fluoroscopy time was 60±10mins. In selected patients with persistent AF, a long-term rate of 60% arrhythmia free survival off AAD can be achieved using this novel T-VAC technique. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  2. Noninvasive Assessment of Tissue Heating During Cardiac Radiofrequency Ablation Using MRI Thermography

    PubMed Central

    Kolandaivelu, Aravindan; Zviman, Menekhem M.; Castro, Valeria; Lardo, Albert C.; Berger, Ronald D.; Halperin, Henry R.

    2010-01-01

    Background Failure to achieve properly localized, permanent tissue destruction is a common cause of arrhythmia recurrence after cardiac ablation. Current methods of assessing lesion size and location during cardiac radiofrequency ablation are unreliable or not suited for repeated assessment during the procedure. MRI thermography could be used to delineate permanent ablation lesions because tissue heating above 50°C is the cause of permanent tissue destruction during radiofrequency ablation. However, image artifacts caused by cardiac motion, the ablation electrode, and radiofrequency ablation currently pose a challenge to MRI thermography in the heart. In the current study, we sought to demonstrate the feasibility of MRI thermography during cardiac ablation. Methods and Results An MRI-compatible electrophysiology catheter and filtered radiofrequency ablation system was used to perform ablation in the left ventricle of 6 mongrel dogs in a 1.5-T MRI system. Fast gradient-echo imaging was performed before and during radiofrequency ablation, and thermography images were derived from the preheating and postheating images. Lesion extent by thermography was within 20% of the gross pathology lesion. Conclusions MR thermography appears to be a promising technique for monitoring lesion formation and may allow for more accurate placement and titration of ablation, possibly reducing arrhythmia recurrences. PMID:20657028

  3. Stereotactic Radiofrequency Ablation (SRFA) of Liver Lesions: Technique Effectiveness, Safety, and Interoperator Performance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Widmann, Gerlig, E-mail: gerlig.widmann@i-med.ac.at; Schullian, Peter, E-mail: peter.schullian@i-med.ac.at; Haidu, Marion, E-mail: marion.haidu@i-med.ac.at

    Purpose: To evaluate technique effectiveness, safety, and interoperator performance of stereotactic radiofrequency ablation (SRFA) of liver lesions. Methods: Retrospective review including 90 consecutive patients from January 2008 to January 2010 with 106 computed tomography-guided SRFA sessions using both single and multiple electrodes for the treatment of 177 lesions: 72 hepatocellular carcinoma (HCC) and 105 metastases with a mean size of 2.9 cm (range 0.5-11 cm). Technique effectiveness and 1-year local recurrence were evaluated by computed tomographic scans. Complications, mortality, and hospital days were recorded. The performance between an experienced and inexperienced interventional radiologist was compared. Results: The overall technique effectivenessmore » after a single SRFA was 95.5% (93.1% for HCC and 97.1% for metastases). Four of the eight unsuccessfully treated lesions could be retreated (secondary technique effectiveness of 97.7%). Local recurrence at 1 year was 2.9%. Technique effectiveness was significantly different for lesions <5 cm (96.7%) and >5 cm (87.5%) (P = 0.044) but not for lesions <3 cm (95.9%) and 3-5 cm (100%). Compared to clear parenchymal property (97.3%), vessel vicinity (93.3%) (P = 0.349) and subcapsular (95.2%) (P = 0.532) had no, but hollow viscera vicinity (83.3%) had a significantly lower technique effectiveness (P = 0.020). Mortality rate was 0.9%. Major complications and hospital days were higher for cirrhosis Child-Pugh B (20%, 7.2 days) than Child-Pugh A (3.1%, 4.7 days) patients and for metastases (5.1%, 4.3 days). There was no significant difference in interoperator performance. Conclusions: RFA allowed for efficient, reliable, and safe ablation of large-volume liver disease.« less

  4. Radiofrequency ablation of liver tumors (I): biological background.

    PubMed

    Vanagas, Tomas; Gulbinas, Antanas; Pundzius, Juozas; Barauskas, Giedrius

    2010-01-01

    Majority of patients suffering from liver tumors are not candidates for surgery. Currently, minimal invasive techniques have become available for local destruction of hepatic tumors. Radiofrequency ablation is based on biological response to tissue hyperthermia. The aim of this article is to review available biological data on tissue destruction mechanisms. Experimental evidence shows that tissue injury following thermal ablation occurs in two distinct phases. The initial phase is direct injury, which is determined by energy applied, tumor biology, and tumor microenvironment. The temperature varies along the ablation zone and this is reflected by different morphological changes in affected tissues. The local hyperthermia alters metabolism, exacerbates tissue hypoxia, and increases thermosensitivity. The second phase - indirect injury - is observed after the cessation of heat stimulus. This phase represents a balance of several promoting and inhibiting mechanisms, such as induction of apoptosis, heat shock proteins, Kupffer cell activation, stimulation of the immune response, release of cytokines, and ischemia-reperfusion injury. A deeper understanding of the underlying mechanisms may possibly lead to refinements in radiofrequency ablation technology, resulting in advanced local tumor control and prolonged overall survival.

  5. Radiofrequency ablation versus electrocautery in tonsillectomy.

    PubMed

    Hall, Daniel J; Littlefield, Philip D; Birkmire-Peters, Deborah P; Holtel, Michael R

    2004-03-01

    The objective of this study was to compare the safety, difficulty of removal, and postoperative pain profile of radiofrequency ablation versus standard electrocautery removal of tonsils. A prospective, blinded study was designed to remove 1 tonsil with each of the 2 methods. Time of operation, estimated blood loss, difficulty of operation, postoperative pain, rate of postoperative hemorrhage, and the patient's preferred technique were evaluated. The operating time was significantly longer (P < 0.007) and the patients reported significantly less pain (P < 0.001) with radiofrequency ablation. There were no differences in blood loss, difficulty of operation, or postoperative hemorrhage rates. The patients preferred the radiofrequency ablation technique (P < 0.001). Radiofrequency ablation is a viable method to remove tonsillar tissue. Operating time for this procedure will likely decrease with experience. There was significantly less pain reported with radiofrequency ablation compared with standard electrocautery.

  6. Single laser based pump-probe technique to study plasma shielding during nanosecond laser ablation of copper thin films

    NASA Astrophysics Data System (ADS)

    Nammi, Srinagalakshmi; Vasa, Nilesh J.; Gurusamy, Balaganesan; Mathur, Anil C.

    2017-09-01

    A plasma shielding phenomenon and its influence on micromachining is studied experimentally and theoretically for laser wavelengths of 355 nm, 532 nm and 1064 nm. A time resolved pump-probe technique is proposed and demonstrated by splitting a single nanosecond Nd3+:YAG laser into an ablation laser (pump laser) and a probe laser to understand the influence of plasma shielding on laser ablation of copper (Cu) clad on polyimide thin films. The proposed nanosecond pump-probe technique allows simultaneous measurement of the absorption characteristics of plasma produced during Cu film ablation by the pump laser. Experimental measurements of the probe intensity distinctly show that the absorption by the ablated plume increases with increase in the pump intensity, as a result of plasma shielding. Theoretical estimation of the intensity of the transmitted pump beam based on the thermo-temporal modeling is in qualitative agreement with the pump-probe based experimental measurements. The theoretical estimate of the depth attained for a single pulse with high pump intensity value on a Cu thin film is limited by the plasma shielding of the incident laser beam, similar to that observed experimentally. Further, the depth of micro-channels produced shows a similar trend for all three wavelengths, however, the channel depth achieved is lesser at the wavelength of 1064 nm.

  7. Ablation-cooled material removal with ultrafast bursts of pulses

    NASA Astrophysics Data System (ADS)

    Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Çetin, Barbaros; Kesim, Denizhan K.; Akçaalan, Önder; Yavaş, Seydi; Aşık, Mehmet D.; Öktem, Bülent; Hoogland, Heinar; Holzwarth, Ronald; Ilday, Fatih Ömer

    2016-09-01

    The use of femtosecond laser pulses allows precise and thermal-damage-free removal of material (ablation) with wide-ranging scientific, medical and industrial applications. However, its potential is limited by the low speeds at which material can be removed and the complexity of the associated laser technology. The complexity of the laser design arises from the need to overcome the high pulse energy threshold for efficient ablation. However, the use of more powerful lasers to increase the ablation rate results in unwanted effects such as shielding, saturation and collateral damage from heat accumulation at higher laser powers. Here we circumvent this limitation by exploiting ablation cooling, in analogy to a technique routinely used in aerospace engineering. We apply ultrafast successions (bursts) of laser pulses to ablate the target material before the residual heat deposited by previous pulses diffuses away from the processing region. Proof-of-principle experiments on various substrates demonstrate that extremely high repetition rates, which make ablation cooling possible, reduce the laser pulse energies needed for ablation and increase the efficiency of the removal process by an order of magnitude over previously used laser parameters. We also demonstrate the removal of brain tissue at two cubic millimetres per minute and dentine at three cubic millimetres per minute without any thermal damage to the bulk.

  8. Ablation-cooled material removal with ultrafast bursts of pulses.

    PubMed

    Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Çetin, Barbaros; Kesim, Denizhan K; Akçaalan, Önder; Yavaş, Seydi; Aşık, Mehmet D; Öktem, Bülent; Hoogland, Heinar; Holzwarth, Ronald; Ilday, Fatih Ömer

    2016-09-01

    The use of femtosecond laser pulses allows precise and thermal-damage-free removal of material (ablation) with wide-ranging scientific, medical and industrial applications. However, its potential is limited by the low speeds at which material can be removed and the complexity of the associated laser technology. The complexity of the laser design arises from the need to overcome the high pulse energy threshold for efficient ablation. However, the use of more powerful lasers to increase the ablation rate results in unwanted effects such as shielding, saturation and collateral damage from heat accumulation at higher laser powers. Here we circumvent this limitation by exploiting ablation cooling, in analogy to a technique routinely used in aerospace engineering. We apply ultrafast successions (bursts) of laser pulses to ablate the target material before the residual heat deposited by previous pulses diffuses away from the processing region. Proof-of-principle experiments on various substrates demonstrate that extremely high repetition rates, which make ablation cooling possible, reduce the laser pulse energies needed for ablation and increase the efficiency of the removal process by an order of magnitude over previously used laser parameters. We also demonstrate the removal of brain tissue at two cubic millimetres per minute and dentine at three cubic millimetres per minute without any thermal damage to the bulk.

  9. Oesophageal Injury During AF Ablation: Techniques for Prevention

    PubMed Central

    Romero, Jorge; Avendano, Ricardo; Grushko, Michael; Diaz, Juan Carlos; Du, Xianfeng; Gianni, Carola; Natale, Andrea

    2018-01-01

    Atrial fibrillation remains the most common arrhythmia worldwide, with pulmonary vein isolation (PVI) being an essential component in the treatment of this arrhythmia. In view of the close proximity of the oesophagus with the posterior wall of the left atrium, oesophageal injury prevention has become a major concern during PVI procedures. Oesophageal changes varying from erythema to fistulas have been reported, with atrio-oesophageal fistulas being the most feared as they are associated with major morbidity and mortality. This review article provides a detailed description of the risk factors associated with oesophageal injury during ablation, along with an overview of the currently available techniques to prevent oesophageal injury. We expect that this state of the art review will deliver the tools to help electrophysiologists prevent potential oesophageal injuries, as well as increase the focus on research areas in which evidence is lacking. PMID:29636969

  10. Outcomes of repeat catheter ablation using magnetic navigation or conventional ablation.

    PubMed

    Akca, Ferdi; Theuns, Dominic A M J; Abkenari, Lara Dabiri; de Groot, Natasja M S; Jordaens, Luc; Szili-Torok, Tamas

    2013-10-01

    After initial catheter ablation, repeat procedures could be necessary. This study evaluates the efficacy of the magnetic navigation system (MNS) in repeat catheter ablation as compared with manual conventional techniques (MANs). The results of 163 repeat ablation procedures were analysed. Ablations were performed either using MNS (n = 84) or conventional manual ablation (n = 79). Procedures were divided into four groups based on the technique used during the initial and repeat ablation procedure: MAN-MAN (n = 66), MAN-MNS (n = 31), MNS-MNS (n = 53), and MNS-MAN (n = 13). Three subgroups were analysed: supraventricular tachycardias (SVTs, n = 68), atrial fibrillation (AF, n = 67), and ventricular tachycardias (VT, n = 28). Recurrences were assessed during 19 ± 11 months follow-up. Overall, repeat procedures using MNS were successful in 89.0% as compared with 96.2% in the MAN group (P = ns). The overall recurrence rate was significantly lower using MNS (25.0 vs. 41.4%, P = 0.045). Acute success and recurrence rates for the MAN-MAN, MAN-MNS, MNS-MNS, and MNS-MAN groups were comparable. For the SVT subgroup a higher acute success rate was achieved using MAN (87.9 vs. 100.0%, P = 0.049). The use of MNS for SVT is associated with longer procedure times (205 ± 82 vs. 172 ± 69 min, P = 0.040). For AF procedure and fluoroscopy times were longer (257 ± 72 vs. 185 ± 64, P = 0.001; 59.5 ± 19.3 vs. 41.1 ± 18.3 min, P < 0.001). Less fluoroscopy was used for MNS-guided VT procedures (22.8 ± 14.7 vs. 41.2 ± 10.9, P = 0.011). Our data suggest that overall MNS is comparable with MAN in acute success after repeat catheter ablation. However, MNS is related to fewer recurrences as compared with MAN.

  11. Technical success, technique efficacy and complications of minimally-invasive imaging-guided percutaneous ablation procedures of breast cancer: A systematic review and meta-analysis.

    PubMed

    Mauri, Giovanni; Sconfienza, Luca Maria; Pescatori, Lorenzo Carlo; Fedeli, Maria Paola; Alì, Marco; Di Leo, Giovanni; Sardanelli, Francesco

    2017-08-01

    To systematically review studies concerning imaging-guided minimally-invasive breast cancer treatments. An online database search was performed for English-language articles evaluating percutaneous breast cancer ablation. Pooled data and 95% confidence intervals (CIs) were calculated. Technical success, technique efficacy, minor and major complications were analysed, including ablation technique subgroup analysis and effect of tumour size on outcome. Forty-five studies were analysed, including 1,156 patients and 1,168 lesions. Radiofrequency (n=577; 50%), microwaves (n=78; 7%), laser (n=227; 19%), cryoablation (n=156; 13%) and high-intensity focused ultrasound (HIFU, n=129; 11%) were used. Pooled technical success was 96% (95%CI 94-97%) [laser=98% (95-99%); HIFU=96% (90-98%); radiofrequency=96% (93-97%); cryoablation=95% (90-98%); microwave=93% (81-98%)]. Pooled technique efficacy was 75% (67-81%) [radiofrequency=82% (74-88); cryoablation=75% (51-90); laser=59% (35-79); HIFU=49% (26-74)]. Major complications pooled rate was 6% (4-8). Minor complications pooled rate was 8% (5-13%). Differences between techniques were not significant for technical success (p=0.449), major complications (p=0.181) or minor complications (p=0.762), but significant for technique efficacy (p=0.009). Tumour size did not impact on variables (p>0.142). Imaging-guided percutaneous ablation techniques of breast cancer have a high rate of technical success, while technique efficacy remains suboptimal. Complication rates are relatively low. • Imaging-guided ablation techniques for breast cancer are 96% technically successful. • Overall technique efficacy rate is 75% but largely inhomogeneous among studies. • Overall major and minor complication rates are low (6-8%).

  12. Ion separation effects in mixed-species ablators for inertial-confinement-fusion implosions

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Bellei, Claudio; Ross, J. Steven; Salmonson, Jay

    2015-02-01

    Recent efforts to demonstrate significant self-heating of the fuel and eventual ignition at the National Ignition Facility make use of plastic (CH) ablators [O. A. Hurricane et al., Phys. Plasmas 21, 056314 (2014), 10.1063/1.4874330]. Mainline simulation techniques for modeling CH capsule implosions treat the ablator as an average-atom fluid and neglect potential species separation phenomena. The mass-ablation process for a mixture is shown to lead to the potential for species separation, parasitic energy loss according to thermodynamic arguments, and reduced rocket efficiency. A generalized plasma barometric formula for a multispecies concentration gradient that includes collisionality and steady flows in spherical geometry is presented. A model based on plasma expansion into a vacuum is used to interpret reported experimental evidence for ablator species separation in an inertial-confinement-fusion target [J. S. Ross et al., Rev. Sci. Instrum. 83, 10E323 (2012)]. The possibility of "runaway" hydrogen ions in the thermoelectric field of the ablation front is conjectured.

  13. Ion separation effects in mixed-species ablators for inertial-confinement-fusion implosions.

    PubMed

    Amendt, Peter; Bellei, Claudio; Ross, J Steven; Salmonson, Jay

    2015-02-01

    Recent efforts to demonstrate significant self-heating of the fuel and eventual ignition at the National Ignition Facility make use of plastic (CH) ablators [O. A. Hurricane et al., Phys. Plasmas 21, 056314 (2014)]. Mainline simulation techniques for modeling CH capsule implosions treat the ablator as an average-atom fluid and neglect potential species separation phenomena. The mass-ablation process for a mixture is shown to lead to the potential for species separation, parasitic energy loss according to thermodynamic arguments, and reduced rocket efficiency. A generalized plasma barometric formula for a multispecies concentration gradient that includes collisionality and steady flows in spherical geometry is presented. A model based on plasma expansion into a vacuum is used to interpret reported experimental evidence for ablator species separation in an inertial-confinement-fusion target [J. S. Ross et al., Rev. Sci. Instrum. 83, 10E323 (2012)]. The possibility of "runaway" hydrogen ions in the thermoelectric field of the ablation front is conjectured.

  14. Doping He droplets by laser ablation with a pulsed supersonic jet source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Katzy, R.; Singer, M.; Izadnia, S.

    Laser ablation offers the possibility to study a rich number of atoms, molecules, and clusters in the gas phase. By attaching laser ablated materials to helium nanodroplets, one can gain highly resolved spectra of isolated species in a cold, weakly perturbed system. Here, we present a new setup for doping pulsed helium nanodroplet beams by means of laser ablation. In comparison to more well-established techniques using a continuous nozzle, pulsed nozzles show significant differences in the doping efficiency depending on certain experimental parameters (e.g., position of the ablation plume with respect to the droplet formation, nozzle design, and expansion conditions).more » In particular, we demonstrate that when the ablation region overlaps with the droplet formation region, one also creates a supersonic beam of helium atoms seeded with the sample material. The processes are characterized using a surface ionization detector. The overall doping signal is compared to that of conventional oven cell doping showing very similar dependence on helium stagnation conditions, indicating a comparable doping process. Finally, the ablated material was spectroscopically studied via laser induced fluorescence.« less

  15. Ablative skin resurfacing.

    PubMed

    Agrawal, Nidhi; Smith, Greg; Heffelfinger, Ryan

    2014-02-01

    Ablative laser resurfacing has evolved as a safe and effective treatment for skin rejuvenation. Although traditional lasers were associated with significant thermal damage and lengthy recovery, advances in laser technology have improved safety profiles and reduced social downtime. CO2 lasers remain the gold standard of treatment, and fractional ablative devices capable of achieving remarkable clinical improvement with fewer side effects and shorter recovery times have made it a more practical option for patients. Although ablative resurfacing has become safer, careful patient selection and choice of suitable laser parameters are essential to minimize complications and optimize outcomes. This article describes the current modalities used in ablative laser skin resurfacing and examines their efficacy, indications, and possible side effects. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  16. Three-Catheter Technique for Ablation of Left-Sided Accessory Pathways in Wolff-Parkinson-White is Less Expensive and Equally Successful When Compared to a Five-Catheter Technique.

    PubMed

    Capone, Christine A; Ceresnak, Scott R; Nappo, Lynn; Gates, Gregory J; Schechter, Clyde B; Pass, Robert H

    2015-12-01

    To compare the efficacy, safety, and cost-effectiveness of a three-catheter approach with a conventional five-catheter approach for the mapping and ablation of supraventricular tachycardia in pediatric patients with Wolff-Parkinson-White Syndrome (WPW) and concealed accessory pathways (APs). A retrospective review from 2008 to 2012 of patients less than 21 years with WPW who underwent a three-catheter radiofrequency (RF) ablation of a left-sided AP (ablation, right ventricular [RV] apical, and coronary sinus [CS] decapolar catheters) was performed. The three-catheter group was compared to a control group who underwent a standard five-catheter (ablation, RV apical, CS decapolar, His catheter, and right atrial catheter) ablation for the treatment of left-sided WPW or concealed AP. Demographics, ablation outcomes, and costs were compared between groups. Twenty-eight patients met inclusion criteria with 28 control patients. The groups did not differ in gender, age, weight, or body surface area. Locations of the AP on the mitral annulus were similar between the groups. All patients were ablated via transseptal approach. Note that 28 of 28 in the three-catheter group (100%) and 27 of 28 (96%) controls were acutely successfully ablated (P = 0.31). No complications were encountered. There was no difference in procedural time, time to loss of AP conduction, or number of RF applications. Use of the three-catheter technique resulted in a total savings of $2,465/case, which includes the $680 savings from using fewer catheters as well as the savings from a shortened procedure time. Ablation in patients with WPW and a left-sided AP can be performed using three catheters with similar efficacy and safety while offering significant cost savings compared to a conventional five-catheter approach. © 2015 Wiley Periodicals, Inc.

  17. Interactive Volumetry Of Liver Ablation Zones.

    PubMed

    Egger, Jan; Busse, Harald; Brandmaier, Philipp; Seider, Daniel; Gawlitza, Matthias; Strocka, Steffen; Voglreiter, Philip; Dokter, Mark; Hofmann, Michael; Kainz, Bernhard; Hann, Alexander; Chen, Xiaojun; Alhonnoro, Tuomas; Pollari, Mika; Schmalstieg, Dieter; Moche, Michael

    2015-10-20

    Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm's results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other). As evaluation metric for the statistical validation, the Dice Similarity Coefficient (DSC) has been calculated. The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation. The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.

  18. Interactive Volumetry Of Liver Ablation Zones

    NASA Astrophysics Data System (ADS)

    Egger, Jan; Busse, Harald; Brandmaier, Philipp; Seider, Daniel; Gawlitza, Matthias; Strocka, Steffen; Voglreiter, Philip; Dokter, Mark; Hofmann, Michael; Kainz, Bernhard; Hann, Alexander; Chen, Xiaojun; Alhonnoro, Tuomas; Pollari, Mika; Schmalstieg, Dieter; Moche, Michael

    2015-10-01

    Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm’s results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other). As evaluation metric for the statistical validation, the Dice Similarity Coefficient (DSC) has been calculated. The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation. The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.

  19. Ablative Therapies for Barrett's Esophagus

    PubMed Central

    Garman, Katherine S.; Shaheen, Nicholas J.

    2011-01-01

    Barrett's esophagus has gained increased clinical attention because of its association with esophageal adenocarcinoma, a cancer with increasing incidence and poor survival rates. The goals of ablating Barrett's esophagus are to decrease esophageal cancer rates and to improve overall survival and quality of life. Different techniques have been developed and tested for their effectiveness eradicating Barrett's epithelium. This review assesses the literature associated with different ablative techniques. The safety and efficacy of different techniques are discussed. This review concludes with recommendations for the clinician, including specific strategies for patient care decisions for patients with Barrett's esophagus with varying degrees of dysplasia. PMID:21373836

  20. Ablative therapy for liver tumours

    PubMed Central

    Dick, E A; Taylor-Robinson, S D; Thomas, H C; Gedroyc, W M W

    2002-01-01

    Established ablative therapies for the treatment of primary and secondary liver tumours, including percutaneous ethanol injection, cryotherapy, and radiofrequency ablation, are discussed. Newer techniques such as magnetic resonance imaging guided laser interstitial thermal therapy of liver tumours has produced a median survival rate of 40.8 months after treatment. The merits of this newly emerging technique are discussed, together with future developments, such as focused ultrasound therapy, which holds the promise of non-invasive thermoablation treatment on an outpatient basis. PMID:11950826

  1. Avoiding Complications in Bone and Soft Tissue Ablation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kurup, A. Nicholas, E-mail: kurup.anil@mayo.edu; Schmit, Grant D., E-mail: schmit.grant@mayo.edu; Morris, Jonathan M., E-mail: morris.jonathan@mayo.edu

    As with percutaneous ablation of tumors in the liver, lungs, and kidneys, ablation of bone and non-visceral soft tissue tumors carries risk, primarily from collateral damage to vital structures in proximity to the target tumor. Certain risks are of particular interest when ablating bone and non-visceral soft tissue tumors, namely neural or skin injury, bowel injury, fracture, and gas embolism from damaged applicators. Ablation of large volume tumors also carries special risk. Many techniques may be employed by the interventional radiologist to minimize complications when treating tumors in the musculoskeletal system. These methods include those to depict, displace, or monitormore » critical structures. Thus, measures to provide thermoprotection may be active, such as careful ablation applicator placement and use of various displacement techniques, as well as passive, including employment of direct temperature, radiographic, or neurophysiologic monitoring techniques. Cementoplasty should be considered in certain skeletal locations at risk of fracture. Patients treated with large volume tumors should be monitored for renal dysfunction and properly hydrated. Finally, ablation applicators should be cautiously placed in the constrained environment of intact bone.« less

  2. Is AF Ablation Cost Effective?

    PubMed Central

    Martin-Doyle, William; Reynolds, Matthew R.

    2010-01-01

    The use of catheter ablation to treat AF is increasing rapidly, but there is presently an incomplete understanding of its cost-effectiveness. AF ablation procedures involve significant up-front expenditures, but multiple randomized trials have demonstrated that ablation is more effective than antiarrhythmic drugs at maintaining sinus rhythm in a second-line and possibly first-line rhythm control setting. Although truly long-term data are limited, ablation, as compared with antiarrrhythmic drugs, also appears associated with improved symptoms and quality of life and a reduction in downstream hospitalization and other health care resource utilization. Several groups have developed cost effectiveness models comparing AF ablation primarily to antiarrhythmic drugs and the model results suggest that ablation likely falls within the range generally accepted as cost-effective in developed nations. This paper will review available information on the cost-effectiveness of catheter ablation for the treatment of atrial fibrillation, and discuss continued areas of uncertainty where further research is required. PMID:20936083

  3. 12-month efficacy of a single radiofrequency ablation on autonomously functioning thyroid nodules.

    PubMed

    Bernardi, Stella; Stacul, Fulvio; Michelli, Andrea; Giudici, Fabiola; Zuolo, Giulia; de Manzini, Nicolò; Dobrinja, Chiara; Zanconati, Fabrizio; Fabris, Bruno

    2017-09-01

    Radiofrequency ablation has been advocated as an alternative to radioiodine and/or surgery for the treatment of autonomously functioning benign thyroid nodules. However, only a few studies have measured radiofrequency ablation efficacy on autonomously functioning benign thyroid nodules. The aim of this work was to evaluate the 12-month efficacy of a single session of radiofrequency ablation (performed with the moving shot technique) on solitary autonomously functioning benign thyroid nodules. Thirty patients with a single, benign autonomously functioning benign thyroid nodules, who were either unwilling or ineligible to undergo surgery and radioiodine, were treated with radiofrequency ablation between April 2012 and May 2015. All the patients underwent a single radiofrequency ablation, performed with the 18-gauge needle and the moving shot technique. Clinical, laboratory, and ultrasound evaluations were scheduled at baseline, and after 1, 3, 6, and 12 months from the procedure. A single radiofrequency ablation reduced thyroid nodule volume by 51, 63, 69, and 75 % after 1, 3, 6, and 12 months, respectively. This was associated with a significant improvement of local cervical discomfort and cosmetic score. As for thyroid function, 33 % of the patients went into remission after 3 months, 43 % after 6 months, and 50 % after 12 months from the procedure. This study demonstrates that a single radiofrequency ablation allowed us to withdraw anti-thyroid medication in 50 % of the patients, who remained euthyroid afterwards. This study shows that a single radiofrequency ablation was effective in 50 % of patients with autonomously functioning benign thyroid nodules. Patients responded gradually to the treatment. It is possible that longer follow-up studies might show greater response rates.

  4. Glue septal ablation: A promising alternative to alcohol septal ablation

    PubMed Central

    Aytemir, Kudret; Oto, Ali

    2016-01-01

    Hypertrophic cardiomyopathy (HCM) is defined as myocardial hypertrophy in the absence of another cardiac or systemic disease capable of producing the magnitude of present hypertrophy. In about 70% of patients with HCM, there is left ventricular outflow tract (LVOT) obstruction (LVOTO) and this is known as obstructive type of hypertrophic cardiomyopathy (HOCM). Cases refractory to medical treatment have had two options either surgical septal myectomy or alcohol septal ablation (ASA) to alleviate LVOT gradient. ASA may cause some life-threatening complications including conduction disturbances and complete heart block, hemodynamic compromise, ventricular arrhythmias, distant and massive myocardial necrosis. Glue septal ablation (GSA) is a promising technique for the treatment of HOCM. Glue seems to be superior to alcohol due to some intrinsic advantageous properties of glue such as immediate polymerization which prevents the leak into the left anterior descending coronary artery and it is particularly useful in patients with collaterals to the right coronary artery in whom alcohol ablation is contraindicated. In our experience, GSA is effective and also a safe technique without significant complications. GSA decreases LVOT gradient immediately after the procedure and this reduction persists during 12 months of follow-up. It improves New York Heart Association functional capacity and decrease interventricular septal wall thickness. Further studies are needed in order to assess the long-term efficacy and safety of this technique. PMID:27011786

  5. Atrial Tachycardias Following Atrial Fibrillation Ablation

    PubMed Central

    Sághy, László; Tutuianu, Cristina; Szilágyi, Judith

    2015-01-01

    One of the most important proarrhythmic complications after left atrial (LA) ablation is regular atrial tachycardia (AT) or flutter. Those tachycardias that occur after atrial fibrillation (AF) ablation can cause even more severe symptoms than those from the original arrhythmia prior to the index ablation procedure since they are often incessant and associated with rapid ventricular response. Depending on the method and extent of LA ablation and on the electrophysiological properties of underlying LA substrate, the reported incidence of late ATs is variable. To establish the exact mechanism of these tachycardias can be difficult and controversial but correlates with the ablation technique and in the vast majority of cases the mechanism is reentry related to gaps in prior ablation lines. When tachycardias occur, conservative therapy usually is not effective, radiofrequency ablation procedure is mostly successful, but can be challenging, and requires a complex approach. PMID:25308808

  6. Interferometric analysis of the ablation profile in refractive surgery

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rodríguez, M. I.; López-Olazagasti, E.; Rosales, M. A.; Ramírez-Zavaleta, G.; Cantú, R.; Tepichín, E.

    2008-08-01

    In ophthalmology, the laser excimer corneal surface ablation used to correct the refractive eye defects, such as myopia, astigmatism and hyperopia and, more recently, presbyopia is known as refractive surgery. Typically, the characterization of the corresponding technique, as well as the laser accuracy, is performed by analyzing standard ablation profiles made on PMMA (polymethylmethacrylate) plates. A drawback of this technique is that those plates do not necessarily represent the dimensions of the cornea during the ablation. On the other hand, due to the time varying process of the eye aberrations, the direct eye refractometric measurements can produce some errors. We report in this work the interferometric analysis of the ablation profile obtained with refractive surgery, applied directly on a contact lens. In this case, the resultant ablation profile might be closer to the real profile as well as time invariant. We use, as a reference, a similar contact lens without ablation. The preliminary results of the characterization of the corresponding ablation profile are also presented.

  7. Similarities and differences in ablative and non-ablative iron oxide nanoparticle hyperthermia cancer treatment

    NASA Astrophysics Data System (ADS)

    Petryk, Alicia A.; Misra, Adwiteeya; Kastner, Elliot J.; Mazur, Courtney M.; Petryk, James D.; Hoopes, P. Jack

    2015-03-01

    The use of hyperthermia to treat cancer is well studied and has utilized numerous delivery techniques, including microwaves, radio frequency, focused ultrasound, induction heating, infrared radiation, warmed perfusion liquids (combined with chemotherapy), and recently, metallic nanoparticles (NP) activated by near infrared radiation (NIR) and alternating magnetic field (AMF) based platforms. It has been demonstrated by many research groups that ablative temperatures and cytotoxicity can be produced with locally NP-based hyperthermia. Such ablative NP techniques have demonstrated the potential for success. Much attention has also been given to the fact that NP may be administered systemically, resulting in a broader cancer therapy approach, a lower level of tumor NP content and a different type of NP cancer therapy (most likely in the adjuvant setting). To use NP based hyperthermia successfully as a cancer treatment, the technique and its goal must be understood and utilized in the appropriate clinical context. The parameters include, but are not limited to, NP access to the tumor (large vs. small quantity), cancer cell-specific targeting, drug carrying capacity, potential as an ionizing radiation sensitizer, and the material properties (magnetic characteristics, size and charge). In addition to their potential for cytotoxicity, the material properties of the NP must also be optimized for imaging, detection and direction. In this paper we will discuss the differences between, and potential applications for, ablative and non-ablative magnetic nanoparticle hyperthermia.

  8. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation of liver tumours.

    PubMed

    Wijlemans, J W; Bartels, L W; Deckers, R; Ries, M; Mali, W P Th M; Moonen, C T W; van den Bosch, M A A J

    2012-09-28

    Recent decades have seen a paradigm shift in the treatment of liver tumours from invasive surgical procedures to minimally invasive image-guided ablation techniques. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a novel, completely non-invasive ablation technique that has the potential to change the field of liver tumour ablation. The image guidance, using MR imaging and MR temperature mapping, provides excellent planning images and real-time temperature information during the ablation procedure. However, before clinical implementation of MR-HIFU for liver tumour ablation is feasible, several organ-specific challenges have to be addressed. In this review we discuss the MR-HIFU ablation technique, the liver-specific challenges for MR-HIFU tumour ablation, and the proposed solutions for clinical translation.

  9. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation of liver tumours

    PubMed Central

    Bartels, L.W.; Deckers, R.; Ries, M.; Mali, W.P.Th.M.; Moonen, C.T.W.; van den Bosch, M.A.A.J.

    2012-01-01

    Abstract Recent decades have seen a paradigm shift in the treatment of liver tumours from invasive surgical procedures to minimally invasive image-guided ablation techniques. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a novel, completely non-invasive ablation technique that has the potential to change the field of liver tumour ablation. The image guidance, using MR imaging and MR temperature mapping, provides excellent planning images and real-time temperature information during the ablation procedure. However, before clinical implementation of MR-HIFU for liver tumour ablation is feasible, several organ-specific challenges have to be addressed. In this review we discuss the MR-HIFU ablation technique, the liver-specific challenges for MR-HIFU tumour ablation, and the proposed solutions for clinical translation. PMID:23022541

  10. Maximum voltage gradient technique for optimization of ablation for typical atrial flutter with zero-fluoroscopy approach.

    PubMed

    Deutsch, Karol; Śledź, Janusz; Mazij, Mariusz; Ludwik, Bartosz; Labus, Michał; Karbarz, Dariusz; Pasicka, Bernadetta; Chrabąszcz, Michał; Śledź, Arkadiusz; Klank-Szafran, Monika; Vitali-Sendoz, Laura; Kameczura, Tomasz; Śpikowski, Jerzy; Stec, Piotr; Ujda, Marek; Stec, Sebastian

    2017-06-01

    Radiofrequency catheter ablation (RFCA) is an established effective method for the treatment of typical cavo-tricuspid isthmus (CTI)-dependent atrial flutter (AFL). The introduction of 3-dimensional electro-anatomic systems enables RFCA without fluoroscopy (No-X-Ray [NXR]). The aim of this study was to evaluate the feasibility and effectiveness of CTI RFCA during implementation of the NXR approach and the maximum voltage-guided (MVG) technique for ablation of AFL.Data were obtained from prospective standardized multicenter ablation registry. Consecutive patients with the first RFCA for CTI-dependent AFL were recruited. Two navigation approaches (NXR and fluoroscopy based as low as reasonable achievable [ALARA]) and 2 mapping and ablation techniques (MVG and pull-back technique [PBT]) were assessed. NXR + MVG (n  =  164; age: 63.7 ± 9.5; 30% women), NXR + PBT (n  =  55; age: 63.9 ± 10.7; 39% women); ALARA + MVG (n  =  36; age: 64.2 ± 9.6; 39% women); and ALARA + PBT (n  =  205; age: 64.7 ± 9.1; 30% women) were compared, respectively. All groups were simplified with a 2-catheter femoral approach using 8-mm gold tip catheters (Osypka AG, Germany or Biotronik, Germany) with 15 min of observation. The MVG technique was performed using step-by-step application by mapping the largest atrial signals within the CTI.Bidirectional block in CTI was achieved in 99% of all patients (P  =  NS, between groups). In NXR + MVG and NXR + PBT groups, the procedure time decreased (45.4 ± 17.6 and 47.2 ± 15.7 min vs. 52.6 ± 23.7 and 59.8 ± 24.0 min, P < .01) as compared to ALARA + MVG and ALARA + PBT subgroups. In NXR + MVG and NXR + PBT groups, 91% and 98% of the procedures were performed with complete elimination of fluoroscopy. The NXR approach was associated with a significant reduction in fluoroscopy exposure (from 0.2 ± 1.1 [NXR + PBT] and 0.3 ± 1.6 [NXR + MVG] to 7.7 ± 6.0 min [ALARA + MVG] and 9

  11. Maximum voltage gradient technique for optimization of ablation for typical atrial flutter with zero-fluoroscopy approach

    PubMed Central

    Deutsch, Karol; Śledź, Janusz; Mazij, Mariusz; Ludwik, Bartosz; Labus, Michał; Karbarz, Dariusz; Pasicka, Bernadetta; Chrabąszcz, Michał; Śledź, Arkadiusz; Klank-Szafran, Monika; Vitali-Sendoz, Laura; Kameczura, Tomasz; Śpikowski, Jerzy; Stec, Piotr; Ujda, Marek; Stec, Sebastian

    2017-01-01

    Abstract Radiofrequency catheter ablation (RFCA) is an established effective method for the treatment of typical cavo-tricuspid isthmus (CTI)-dependent atrial flutter (AFL). The introduction of 3-dimensional electro-anatomic systems enables RFCA without fluoroscopy (No-X-Ray [NXR]). The aim of this study was to evaluate the feasibility and effectiveness of CTI RFCA during implementation of the NXR approach and the maximum voltage-guided (MVG) technique for ablation of AFL. Data were obtained from prospective standardized multicenter ablation registry. Consecutive patients with the first RFCA for CTI-dependent AFL were recruited. Two navigation approaches (NXR and fluoroscopy based as low as reasonable achievable [ALARA]) and 2 mapping and ablation techniques (MVG and pull-back technique [PBT]) were assessed. NXR + MVG (n  =  164; age: 63.7 ± 9.5; 30% women), NXR + PBT (n  =  55; age: 63.9 ± 10.7; 39% women); ALARA + MVG (n  =  36; age: 64.2 ± 9.6; 39% women); and ALARA + PBT (n  =  205; age: 64.7 ± 9.1; 30% women) were compared, respectively. All groups were simplified with a 2-catheter femoral approach using 8-mm gold tip catheters (Osypka AG, Germany or Biotronik, Germany) with 15 min of observation. The MVG technique was performed using step-by-step application by mapping the largest atrial signals within the CTI. Bidirectional block in CTI was achieved in 99% of all patients (P  =  NS, between groups). In NXR + MVG and NXR + PBT groups, the procedure time decreased (45.4 ± 17.6 and 47.2 ± 15.7 min vs. 52.6 ± 23.7 and 59.8 ± 24.0 min, P < .01) as compared to ALARA + MVG and ALARA + PBT subgroups. In NXR + MVG and NXR + PBT groups, 91% and 98% of the procedures were performed with complete elimination of fluoroscopy. The NXR approach was associated with a significant reduction in fluoroscopy exposure (from 0.2 ± 1.1 [NXR + PBT] and 0.3 ± 1.6 [NXR + MVG] to 7.7 ± 6.0 min [ALARA

  12. Interactive Volumetry Of Liver Ablation Zones

    PubMed Central

    Egger, Jan; Busse, Harald; Brandmaier, Philipp; Seider, Daniel; Gawlitza, Matthias; Strocka, Steffen; Voglreiter, Philip; Dokter, Mark; Hofmann, Michael; Kainz, Bernhard; Hann, Alexander; Chen, Xiaojun; Alhonnoro, Tuomas; Pollari, Mika; Schmalstieg, Dieter; Moche, Michael

    2015-01-01

    Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm’s results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other). As evaluation metric for the statistical validation, the Dice Similarity Coefficient (DSC) has been calculated. The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation. The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow. PMID:26482818

  13. Alternate energy sources for catheter ablation.

    PubMed

    Wang, P J; Homoud, M K; Link, M S; Estes III, N A

    1999-07-01

    Because of the limitations of conventional radiofrequency ablation in creating large or linear lesions, alternative energy sources have been used as possible methods of catheter ablation. Modified radiofrequency energy, cryoablation, and microwave, laser, and ultrasound technologies may be able to create longer, deeper, and more controlled lesions and may be particularly suited for the treatment of ventricular tachycardias and for linear atrial ablation. Future studies will establish the efficacy of these new and promising technologies.

  14. Real-time thickness measurement of MCC ablator material

    NASA Technical Reports Server (NTRS)

    Greenway, R. Bryan, Jr.

    1994-01-01

    One of the most favorable characteristics of the Space Shuttle Program is the reusability of two of its primary components: the orbiter itself and the Solid Rocket Boosters (SRB). The SRB's provide the primary source of propulsion for the Space Shuttle during take-off after which they are recovered for refurbishment and reuse. During refurbishment, the SRB's are stripped of all remaining ablative (heat resistant) coating. A new layer is applied to the appropriate sections (nose cone, frustum, forward skirt, and aft skirt). It is the process of applying the ablative coating which provided the impetus for this project. The thickness of this protective layer is considered to be of primary importance to the level of thermal protection provided. The objectives of this effort are to investigate possible techniques for measuring the thickness of MCC, and if possible to test the specific capabilities of those considered good candidates for implementation. The system would be able to take measurements in real-time as close to the spray gun as possible. This will allow the information to be used in the control of the process without an inordinate time delay between a measurement and its appropriate response. The thickness of the deposited material is to be measured with less than 0.100 in if uncertainty. This is the defined tolerance window for the ablator thickness. Finally, it must operate within the confines of the chamber which encloses the turntable, robot, and spray system, and therefore is required to be insensitive to, or at least maintainable in, that environment.

  15. Phrenic nerve protection via packing of gauze into the pericardial space during ablation of cristal atrial tachycardia in a child.

    PubMed

    Takahashi, Kazuhiro; Fuchigami, Tai; Nabeshima, Taisuke; Sashinami, Arata; Nakayashiro, Mami

    2016-03-01

    The success of catheter ablation of focal atrial tachycardia is limited by possible collateral damage to the phrenic nerve. Protection of the phrenic nerve is required. Here we present a case of a 9-year-old girl having a history of an unsuccessful catheter ablation of a focal atrial tachycardia near the crista terminalis (because of proximity of the phrenic nerve) who underwent a successful ablation by means of a novel technique for phrenic nerve protection: packing of gauze into the pericardial space. This method is a viable approach for patients with a failed endocardial ablation due to the proximity of the phrenic nerve.

  16. In vivo comparison of simultaneous versus sequential injection technique for thermochemical ablation in a porcine model.

    PubMed

    Cressman, Erik N K; Shenoi, Mithun M; Edelman, Theresa L; Geeslin, Matthew G; Hennings, Leah J; Zhang, Yan; Iaizzo, Paul A; Bischof, John C

    2012-01-01

    To investigate simultaneous and sequential injection thermochemical ablation in a porcine model, and compare them to sham and acid-only ablation. This IACUC-approved study involved 11 pigs in an acute setting. Ultrasound was used to guide placement of a thermocouple probe and coaxial device designed for thermochemical ablation. Solutions of 10 M acetic acid and NaOH were used in the study. Four injections per pig were performed in identical order at a total rate of 4 mL/min: saline sham, simultaneous, sequential, and acid only. Volume and sphericity of zones of coagulation were measured. Fixed specimens were examined by H&E stain. Average coagulation volumes were 11.2 mL (simultaneous), 19.0 mL (sequential) and 4.4 mL (acid). The highest temperature, 81.3°C, was obtained with simultaneous injection. Average temperatures were 61.1°C (simultaneous), 47.7°C (sequential) and 39.5°C (acid only). Sphericity coefficients (0.83-0.89) had no statistically significant difference among conditions. Thermochemical ablation produced substantial volumes of coagulated tissues relative to the amounts of reagents injected, considerably greater than acid alone in either technique employed. The largest volumes were obtained with sequential injection, yet this came at a price in one case of cardiac arrest. Simultaneous injection yielded the highest recorded temperatures and may be tolerated as well as or better than acid injection alone. Although this pilot study did not show a clear advantage for either sequential or simultaneous methods, the results indicate that thermochemical ablation is attractive for further investigation with regard to both safety and efficacy.

  17. [Percutaneous lung thermo-ablation].

    PubMed

    Palussière, Jean; Catena, Vittorio; Gaubert, Jean-Yves; Buy, Xavier; de Baere, Thierry

    2017-05-01

    Percutaneous lung thermo-ablation has steadily been developed over the past 15years. Main indications are early stage non-small cell lung carcinoma (NSCLC) for non-surgical patients and slow evolving localized metastatic disease, either spontaneous or following a general treatment. Radiofrequency, being the most evaluated technique, offers a local control rate of about 80-90% for tumors <3 cm in diameter. With excellent tolerance and very few complications, radiofrequency may be proposed for patients with a chronic disease. Other ablation techniques under investigation such as microwaves and cryotherapy could allow overcoming radiofrequency limits. Furthermore, stereotactic radiotherapy proposed for the same indications is efficient. Comparative studies are warranted to differentiate these techniques in terms of efficacy, tolerance and cost-effectiveness. Copyright © 2017 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.

  18. Technique for CT Fluoroscopy-Guided Lumbar Medial Branch Blocks and Radiofrequency Ablation.

    PubMed

    Amrhein, Timothy J; Joshi, Anand B; Kranz, Peter G

    2016-09-01

    The purpose of this study is to describe the procedure for CT fluoroscopy-guided lumbar medial branch blocks and facet radiofrequency ablation. CT fluoroscopic guidance allows more-precise needle tip positioning and is an alternative method for performing medial branch blocks and facet radiofrequency ablation.

  19. Slow Pathway Radiofrequency Ablation Using Magnetic Navigation: A Description of Technique and Retrospective Case Analysis.

    PubMed

    Bhaskaran, Abhishek; Albarri, Maha; Ross, Neil; Al Raisi, Sara; Samanta, Rahul; Roode, Leonette; Nadri, Fazlur; Ng, Jeanette; Thomas, Stuart; Thiagalingam, Aravinda; Kovoor, Pramesh

    2017-12-01

    The Magnetic Navigation System (MNS) catheter was shown to be stable in the presence of significant cardiac wall motion and delivered more effective lesions compared to manual control. This stability could potentially make AV junctional re-entrant tachycardia (AVNRT) ablation safer. The aim of this study is to describe the method of mapping and ablation of AVNRT with MNS and 3-D electro-anatomical mapping system (CARTO, Biosense Webster, Diamond bar, CA, USA) anatomical mapping, with a view to improve the safety of ablation. The method of precise mapping and ablation with MNS is described. Consecutive AVNRT cases (n=30) from 2012 January to 2015 November, in which magnetic navigation was used, are analysed. Ablation was successful in 27 (90%) out of 30 patients. In three cases, ablation was abandoned due to the proximity of the three-dimensional His image to the potential ablation site. No complications, including AV nodal injury, occurred. The distance from the nearest His position to successful ablation site in both LAO and RAO projections of CARTO images was 26.4±8.8 and 27±7.7mm respectively. Only in two (9%) patients, ablation needed to be extended superior to the plane of coronary sinus ostium, towards the His bundle region, to achieve slow pathway modification. AVNRT ablation with MNS allows for accurate mapping of the AV node and stable ablation at a safe distance, which could help avoid AV nodal injury. We recommend this modality for younger patients with AVNRT. Copyright © 2017. Published by Elsevier B.V.

  20. Safe and rapid isolation of pulmonary veins using a novel circular ablation catheter and duty-cycled RF generator.

    PubMed

    Fredersdorf, Sabine; Weber, Stefan; Jilek, Clemens; Heinicke, Norbert; VON Bary, Christian; Jungbauer, Carsten; Riegger, Günter A; Hamer, Okka W; Jeron, Andreas

    2009-10-01

    Ablation of atrial fibrillation (AF) has been one of the most difficult and time-consuming electrophysiological procedures. Due to the rapidly increasing demand for ablation procedures, technical advances would be helpful to reduce complexity and procedure time in AF ablation. Therefore, we investigated the feasibility of a single-catheter technique for pulmonary vein (PV) isolation utilizing a decapolar catheter combined with a duty-cycled, unipolar-bipolar radiofrequency (RF) generator. AF mapping and ablation was performed in 21 consecutive patients (mean age 59 +/- 12 years, 9 males) with paroxysmal AF (n = 17) and persistent AF (n = 4). The ablation catheter was forwarded to the LA via single-transseptal puncture. All electrodes were energized in 2 to 5 applications per vein, followed by segmental RF applications, as needed, to achieve electrical isolation. To assess left atrial anatomy for purposes of catheter manipulation, and later evaluate the possibility of asymptomatic PV-stenosis, CT or MR imaging was performed both prior to ablation and at 6-month follow-up. Isolation could be achieved in 85/86 veins (99%). Procedure time for ablation was 81 +/- 13 minutes, and fluoroscopy time was 30 +/- 11 minutes. There were no procedural complications. Success rate at 6 months was 86% (18/21). MR or CT imaging excluded asymptomatic PV-stenosis. Mapping and ablation of PVs can be performed in a safe and efficient manner using a single-catheter technique, with short procedure times and minimal learning curve. Thus, this system may be of high interest not only for high volume but all centers performing AF ablation.

  1. Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

    PubMed Central

    Lee, Jeong Hyun; Valcavi, Roberto; Pacella, Claudio M.; Rhim, Hyunchul; Na, Dong Gyu

    2011-01-01

    Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation. PMID:21927553

  2. Laser-Ablation (U-Th)/He Geochronology

    NASA Astrophysics Data System (ADS)

    Hodges, K.; Boyce, J.

    2003-12-01

    ablation experiments results in considerably worse spatial resolution than that typically possible for 40Ar/39Ar laser microprobe dating, it is possible to site the LA-ICPMS ablation pit within a few microns of the pit used for He extraction, or to simply re-occupy and enlarge the original ablation pit. The potential effective spatial resolution of the technique is thus on the order of a few tens to roughly 100 microns. As a proof-of-concept exercise, we have applied this technique to fluorapatite from Cerro de Mercado, Durango, Mexico, which has a generally accepted (U-Th)/He age of 32.1 +/- 3.4 Ma (2 sigma) based on single-crystal fusion analyses reported by House et al. (2000, EPSL). Using the approach described above, we made 48 separate age measurements on a 12 mm polished section cut through a single crystal of Durango fluorapatite perpendicular to its c axis. The measured dates yield a mean of 34.9 +/- 5.1 Ma (2 sigma), with a total dispersion of dates comparable to that reported by House et al. Much of the apparent age variation observed in both studies is due to documented U+Th heterogeneities in single crystals of the Durango fluorapatite. Nevertheless, the consistency of the laser ablation and conventional results for this material is striking. Compared to conventional laser and furnace methods of (U-Th)/He geochronology, the laser microprobe approach offers substantially improved spatial resolution, and the ability to avoid (or at least minimize) alpha-ejection corrections. In addition, the method affords improved sample throughput, such that age estimates for homogeneous materials can be made with considerably higher precision based on a larger number of analyses.

  3. Epicardial Radiofrequency Ablation Failure During Ablation Procedures for Ventricular Arrhythmias: Reasons and Implications for Outcomes.

    PubMed

    Baldinger, Samuel H; Kumar, Saurabh; Barbhaiya, Chirag R; Mahida, Saagar; Epstein, Laurence M; Michaud, Gregory F; John, Roy; Tedrow, Usha B; Stevenson, William G

    2015-12-01

    Radiofrequency ablation (RFA) from the epicardial space for ventricular arrhythmias is limited or impossible in some cases. Reasons for epicardial ablation failure and the effect on outcome have not been systematically analyzed. We assessed reasons for epicardial RFA failure relative to the anatomic target area and the type of heart disease and assessed the effect of failed epicardial RFA on outcome after ablation procedures for ventricular arrhythmias in a large single-center cohort. Epicardial access was attempted during 309 ablation procedures in 277 patients and was achieved in 291 procedures (94%). Unlimited ablation in an identified target region could be performed in 181 cases (59%), limited ablation was possible in 22 cases (7%), and epicardial ablation was deemed not feasible in 88 cases (28%). Reasons for failed or limited ablation were unsuccessful epicardial access (6%), failure to identify an epicardial target (15%), proximity to a coronary artery (13%), proximity to the phrenic nerve (6%), and complications (<1%). Epicardial RFA was impeded in the majority of cases targeting the left ventricular summit region. Acute complications occurred in 9%. The risk for acute ablation failure was 8.3× higher (4.5-15.0; P<0.001) after no or limited epicardial RFA compared with unlimited RFA, and patients with unlimited epicardial RFA had better recurrence-free survival rates (P<0.001). Epicardial RFA for ventricular arrhythmias is often limited even when pericardial access is successful. Variability of success is dependent on the target area, and the presence of factors limiting ablation is associated with worse outcomes. © 2015 American Heart Association, Inc.

  4. Hybrid nanocomposite coatings from metal (Mg alloy)-drug deposited onto medical implant by laser adaptive ablation deposition technique

    NASA Astrophysics Data System (ADS)

    Serbezov, Valery; Sotirov, Sotir; Serbezov, Svetlin

    2013-03-01

    Drug-eluting medical implants are active implants whose function is to create healing effects. The current requirements for active medical coatings for Drug-eluting medical implants are to be biocompatible, biodegradable, polymer free, mechanically stable and enable a controlled release of one or more drugs and defined degradation. This brings hybrid nanocomposite coatings into focus especially in the field of cardiovascular implants. We studied the properties of Metal (Mg alloy)-Paclitaxel coatings obtained by novel Laser Adaptive Ablation Deposition Technique (LAAD) onto cardiovascular stents from 316 LVM stainless steel material. The morphology and topology of coatings were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Comparative measurements were made of the morphology and topology of hybrid, polymer free nanocomposite coatings deposited by LAAD and polymerdrug coatings deposited by classical spray technique. The coatings obtained by LAAD are homogeneous without damages and cracks. Metal nanoparticles with sizes from 40 nm to 230 nm were obtained in drug matrixes. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of metal nanoparticles presence in hybrid nanocomposites coatings. The new technology opens up possibilities to obtain new hybrid nanocomposite coatings with applications in medicine, pharmacy and biochemistry.

  5. [Catheter ablation for paroxysmal atrial fibrillation: new generation cryoballoon or contact force sensing radiofrequency ablation?].

    PubMed

    Nagy, Zsófia; Kis, Zsuzsanna; Som, Zoltán; Földesi, Csaba; Kardos, Attila

    2016-05-29

    Contact force sensing radiofrequency ablation and the new generation cryoballoon ablation are prevalent techniques for the treatment of paroxysmal atrial fibrillation. The authors aimed to compare the procedural and 1-year outcome of patients after radiofrequency and cryoballoon ablation. 96 patients with paroxysmal atrial fibrillation (radiofrequency ablation: 58, cryoballoon: 38 patients; 65 men and 31 women aged 28-70 years) were enrolled. At postprocedural 1, 3, 6 and 12 months ECG, Holter monitoring and telephone interviews were performed. Procedure and fluorosocopy time were: radiofrequency ablation, 118.5 ± 15 min and 15.8 ± 6 min; cryoballoon, 73.5 ± 16 min (p<0.05) and 13.8 ± 4.,1 min (p = 0.09), respectively. One year later freedom from atrial fibrillation was achieved in 76.5% of patients who underwent radiofrequency ablation and in 81% of patients treated with cryoballoon. Temporary phrenic nerve palsy occurred in two patients and pericardial tamponade developed in one patient. In this single center study freedom from paroxysmal atrial fibrillation was similar in the two groups with significant shorter procedure time in the cryoballoon group.

  6. Visualizing ex vivo radiofrequency and microwave ablation zones using electrode vibration elastography

    PubMed Central

    DeWall, Ryan J.; Varghese, Tomy; Brace, Chris L.

    2012-01-01

    Purpose: Electrode vibration elastography is a new shear wave imaging technique that can be used to visualize thermal ablation zones. Prior work has shown the ability of electrode vibration elastography to delineate radiofrequency ablations; however, there has been no previous study of delineation of microwave ablations or radiological–pathological correlations using multiple observers. Methods: Radiofrequency and microwave ablations were formed in ex vivo bovine liver tissue. Their visualization was compared on shear wave velocity and maximum displacement images. Ablation dimensions were compared to gross pathology. Elastographic imaging and gross pathology overlap and interobserver variability were quantified using similarity measures. Results: Elastographic imaging correlated with gross pathology. Correlation of area estimates was better in radiofrequency than in microwave ablations, with Pearson coefficients of 0.79 and 0.54 on shear wave velocity images and 0.90 and 0.70 on maximum displacement images for radiofrequency and microwave ablations, respectively. The absolute relative difference in area between elastographic imaging and gross pathology was 18.9% and 22.9% on shear wave velocity images and 16.0% and 23.1% on maximum displacement images for radiofrequency and microwave ablations, respectively. Conclusions: Statistically significant radiological–pathological correlation was observed in this study, but correlation coefficients were lower than other modulus imaging techniques, most notably in microwave ablations. Observers provided similar delineations for most thermal ablations. These results suggest that electrode vibration elastography is capable of imaging thermal ablations, but refinement of the technique may be necessary before it can be used to monitor thermal ablation procedures clinically. PMID:23127063

  7. Histopathology of breast cancer after magnetic resonance-guided high-intensity focused ultrasound and radiofrequency ablation.

    PubMed

    Knuttel, Floortje M; Waaijer, Laurien; Merckel, Laura G; van den Bosch, Maurice A A J; Witkamp, Arjen J; Deckers, Roel; van Diest, Paul J

    2016-08-01

    Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation and radiofrequency ablation (RFA) are being researched as possible substitutes for surgery in breast cancer patients. The histopathological appearance of ablated tissue has not been studied in great detail. This study aimed to compare histopathological features of breast cancer after MR-HIFU ablation and RFA. MR-HIFU ablation and RFA were performed in- and ex-vivo. Tumours in six mastectomy specimens were partially ablated with RFA or MR-HIFU. In-vivo MR-HIFU ablation was performed 3-6 days before excision; RFA was performed in the operation room. Tissue was fixed in formalin and processed to haematoxylin and eosin (H&E) and cytokeratin-8 (CK-8)-stained slides. Morphology and cell viability were assessed. Ex-vivo ablation resulted in clear morphological changes after RFA versus subtle differences after MR-HIFU. CK-8 staining was decreased or absent. H&E tended to underestimate the size of thermal damage. In-vivo MR-HIFU resulted in necrotic-like changes. Surprisingly, some ablated lesions were CK-8-positive. Histopathology after in-vivo RFA resembled ex-vivo RFA, with hyper-eosinophilic stroma and elongated nuclei. Lesion borders were sharp after MR-HIFU and indistinct after RFA. Histopathological differences between MR-HIFU-ablated tissue and RF-ablated tissue were demonstrated. CK-8 was more reliable for cell viability assessment than H&E when used directly after ablation, while H&E was more reliable in ablated tissue left in situ for a few days. Our results contribute to improved understanding of histopathological features in breast cancer lesions treated with minimally invasive ablative techniques. © 2016 John Wiley & Sons Ltd.

  8. Green and Fast Laser Fusion Technique for Bulk Silicate Rock Analysis by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry.

    PubMed

    Zhang, Chenxi; Hu, Zhaochu; Zhang, Wen; Liu, Yongsheng; Zong, Keqing; Li, Ming; Chen, Haihong; Hu, Shenghong

    2016-10-18

    Sample preparation of whole-rock powders is the major limitation for their accurate and precise elemental analysis by laser ablation inductively-coupled plasma mass spectrometry (ICPMS). In this study, a green, efficient, and simplified fusion technique using a high energy infrared laser was developed for major and trace elemental analysis. Fusion takes only tens of milliseconds for each sample. Compared to the pressed pellet sample preparation, the analytical precision of the developed laser fusion technique is higher by an order of magnitude for most elements in granodiorite GSP-2. Analytical results obtained for five USGS reference materials (ranging from mafic to intermediate to felsic) using the laser fusion technique generally agree with recommended values with discrepancies of less than 10% for most elements. However, high losses (20-70%) of highly volatile elements (Zn and Pb) and the transition metal Cu are observed. The achieved precision is within 5% for major elements and within 15% for most trace elements. Direct laser fusion of rock powders is a green and notably simple method to obtain homogeneous samples, which will significantly accelerate the application of laser ablation ICPMS for whole-rock sample analysis.

  9. PSF and MTF comparison of two different surface ablation techniques for laser visual correction

    NASA Astrophysics Data System (ADS)

    Cruz Félix, Angel Sinue; López Olazagasti, Estela; Rosales, Marco A.; Ibarra, Jorge; Tepichín Rodríguez, Eduardo

    2009-08-01

    It is well known that the Zernike expansion of the wavefront aberrations has been extensively used to evaluate the performance of image forming optical systems. Recently, these techniques were adopted in the field of Ophthalmology to evaluate the objective performance of the human ocular system. We have been working in the characterization and evaluation of the performance of normal human eyes; i.e., eyes which do not require any refractive correction (20/20 visual acuity). These data provide us a reference model to analyze Pre- and Post-Operated results from eyes that have been subjected to laser refractive surgery. Two different ablation techniques are analyzed in this work. These techniques were designed to correct the typical refractive errors known as myopia, hyperopia, and presbyopia. When applied to the corneal surface, these techniques provide a focal shift and, in principle, an improvement of the visual performance. These features can be suitably described in terms of the PSF and MTF of the corresponding Pre- and Post-Operated wavefront aberrations. We show the preliminary results of our comparison.

  10. Organized Atrial Tachycardias after Atrial Fibrillation Ablation

    PubMed Central

    Castrejón-Castrejón, Sergio; Ortega, Marta; Pérez-Silva, Armando; Doiny, David; Estrada, Alejandro; Filgueiras, David; López-Sendón, José L.; Merino, José L.

    2011-01-01

    The efficacy of catheter-based ablation techniques to treat atrial fibrillation is limited not only by recurrences of this arrhythmia but also, and not less importantly, by new-onset organized atrial tachycardias. The incidence of such tachycardias depends on the type and duration of the baseline atrial fibrillation and specially on the ablation technique which was used during the index procedure. It has been repeatedly reported that the more extensive the left atrial surface ablated, the higher the incidence of organized atrial tachycardias. The exact origin of the pathologic substrate of these trachycardias is not fully understood and may result from the interaction between preexistent regions with abnormal electrical properties and the new ones resultant from radiofrequency delivery. From a clinical point of view these atrial tachycardias tend to remit after a variable time but in some cases are responsible for significant symptoms. A precise knowledge of the most frequent types of these arrhythmias, of their mechanisms and components is necessary for a thorough electrophysiologic characterization if a new ablation procedure is required. PMID:21941669

  11. X-ray Micro-Tomography of Ablative Heat Shield Materials

    NASA Technical Reports Server (NTRS)

    Panerai, Francesco; Ferguson, Joseph; Borner, Arnaud; Mansour, Nagi N.; Barnard, Harold S.; MacDowell, Alastair A.; Parkinson, Dilworth Y.

    2016-01-01

    X-ray micro-tomography is a non-destructive characterization technique that allows imaging of materials structures with voxel sizes in the micrometer range. This level of resolution makes the technique very attractive for imaging porous ablators used in hypersonic entry systems. Besides providing a high fidelity description of the material architecture, micro-tomography enables computations of bulk material properties and simulations of micro-scale phenomena. This presentation provides an overview of a collaborative effort between NASA Ames Research Center and Lawrence Berkeley National Laboratory, aimed at developing micro-tomography experiments and simulations for porous ablative materials. Measurements are carried using x-rays from the Advanced Light Source at Berkeley Lab on different classes of ablative materials used in NASA entry systems. Challenges, strengths and limitations of the technique for imaging materials such as lightweight carbon-phenolic systems and woven textiles are discussed. Computational tools developed to perform numerical simulations based on micro-tomography are described. These enable computations of material properties such as permeability, thermal and radiative conductivity, tortuosity and other parameters that are used in ablator response models. Finally, we present the design of environmental cells that enable imaging materials under simulated operational conditions, such as high temperature, mechanical loads and oxidizing atmospheres.Keywords: Micro-tomography, Porous media, Ablation

  12. A Novel Microwave Catheter Can Perform Noncontact Circumferential Endocardial Ablation in a Model of Pulmonary Vein Isolation.

    PubMed

    Qian, Pierre; Barry, Michael Anthony; Nguyen, Trang; Ross, David; Kovoor, Pramesh; McEwan, Alistair; Thomas, Stuart; Thiagalingam, Aravinda

    2015-07-01

    Pulmonary vein isolation is an effective treatment for atrial fibrillation. Current endocardial ablation techniques require catheter contact for lesion formation. Inadequate or inconsistent catheter contact results in difficulty with achieving acute and long-term isolation and consequent atrial arrhythmia recurrence. Microwave energy produces radiant heating and therefore can be used for noncontact catheter ablation. We hypothesized that it is possible to design a microwave catheter to produce a circumferential transmural thermal lesion in an in vitro model of a pulmonary vein antrum. A monopole microwave catheter with a sideways firing axially symmetrical heating pattern was designed. Noncontact ablations were performed in a perfused pulmonary vein model constructed from microwave myocardial phantom embedded with a sheet of thermochromic liquid crystal to permit visualization and measurement of thermal lesions from color changes. 1200 J ablations were performed at 150 W for 80 seconds and 120 W for 100 seconds at high (0.8 L/min) and low (0.06 L/min) flow through the modeled pulmonary vein. Myocardial tissue was substituted for the phantom material and ablations repeated at 150 W for 180 seconds and stained with nitro-blue tetrazolium. The catheter was able to induce deep circumferential antral lesions in myocardial phantom and myocardial tissue. Higher power and shorter ablations delivering the same amount of microwave energy resulted in larger lesions with less surface sparing. A microwave catheter can be designed to produce a circumferential thermal lesion on noncontact ablation and may have possible applications for pulmonary vein isolation. © 2015 Wiley Periodicals, Inc.

  13. Hybrid laparoscopic and robotic ultrasound-guided radiofrequency ablation-assisted clampless partial nephrectomy.

    PubMed

    Nadler, Robert B; Perry, Kent T; Smith, Norm D

    2009-07-01

    To describe a clampless approach made possible by creating an avascular plane of tissue with radiofrequency ablation. Laparoscopic partial nephrectomy is slowly gaining acceptance as a method to treat small (<4 cm) and select moderate (<7 cm) renal masses. The intricacies of laparoscopic suturing, which result in prolonged warm ischemia times, have delayed the widespread acceptance of this technique among urologists. Laparoscopic suturing to close the collecting system was done using the da Vinci robot. An avascular plane of tissue from coagulation necrosis was achieved with the Habib 4X radiofrequency ablation device and the Rita 1500X generator. Typically, we used a power setting of 50 W but have found settings as low as 25 W necessary to provide hemostasis for larger vessels. The tumor was then sharply excised with a negative margin using robotic scissors and electrocautery to facilitate tissue cutting. Retrograde injection of methylthioninium chloride and saline through an externalized ureteral catheter allowed for precise sutured closure of the collecting system. FloSeal and BioGlue were then applied, making surgical bolsters or parenchymal sutures unnecessary. Intraoperative histologic evaluation of the surgical margin and repeat resection of the tumor bed was possible because the renal hilum was not clamped, and no warm ischemia was used. This technique, which combines the improving technologies of robotic surgery, intraoperative laparoscopic ultrasonography, and radiofrequency ablation, might make more surgeons comfortable with the intricacies of laparoscopic suturing and eliminate prolonged warm ischemia times. Overall, this method should result in more patients being able to undergo minimally invasive laparoscopic partial nephrectomy.

  14. Selective Angiography Using the Radiofrequency Catheter: An Alternative Technique for Mapping and Ablation in the Aortic Cusps.

    PubMed

    Roca-Luque, Ivo; Rivas, Nuria; Francisco, Jaume; Perez, Jordi; Acosta, Gabriel; Oristrell, Gerard; Terricabres, Maria; Garcia-Dorado, David; Moya, Angel

    2017-01-01

    Ablation in aortic cusps could be necessary in up to 15% of the patients, especially in para-Hisian atrial tachycardia and ventricular arrhythmias arising from outflow tracts. Risk of coronary damage has led to recommendation of systematic coronary angiography (CA) during the procedure. Other image tests as intravascular (ICE) or transesophageal echocardiography (TEE) have been proposed. Both methods have limitations: additional vascular access for ICE and need for additional CA in some patients in case of TEE. We describe an alternative method to assess relation of catheter tip and coronary ostia during ablation in aortic cusps without additional vascular accesses by performing selective angiography with the ablation catheter. We prospectively evaluated 12 consecutive patients (69.3 ± 8.5, 6 female) who underwent ablation in right (1), left (5), and noncoronary cusps (6). We performed angiography through the ablation cooled tip radiofrequency catheter at the ablation site. Ablation was effective in 91.6% of the patients (3 patients needed additional ablation out of coronary cusps: pulmonary cusp, right ventricular outflow tract (RVOT), and coronary sinus and 1 patient underwent a second procedure because recurrence). No complications occurred neither during procedure nor follow-up (6.2 ± 3.8 months). No technical problems occurred with the ablation catheter after contrast injection. Selective angiography through a cooled-tip radiofrequency ablation catheter is feasible to assess relation of coronary ostia and ablation site when ablation in aortic cusps. It allows continuous real-time assessment of this relation, avoids the need for additional vascular accesses and no complications occurred in our series. © 2016 Wiley Periodicals, Inc.

  15. The effect of asteroid topography on surface ablation deflection

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.; Scheeres, Daniel J.

    2017-02-01

    Ablation techniques for deflecting hazardous asteroids deposit energy into the asteroid's surface, causing an effective thrust on the asteroid as the ablating material leaves normal to the surface. Although it has long been recognized that surface topography plays an important role in determining the deflection capabilities, most studies to date have ignored this aspect of the model. This paper focuses on understanding the topography for real asteroid shapes, and how this topography can change the deflection performance of an ablation technique. The near Earth asteroids Golevka, Bennu, and Itokawa are used as the basis for this study, as all three have high-resolution shape models available. This paper shows that naive targeting of an ablation method without accounting for the surface topography can lower the deflection performance by up to 20% in the cases studied in terms of the amount of acceleration applied in the desired direction. If the ablation thrust level is assumed to be 100 N, as used elsewhere in the literature, this misapplication of thrust translates to tens of kilometers per year in decreased semimajor axis change. However, if the ablation method can freely target any visible point on the surface of the asteroid, almost all of this performance can be recovered.

  16. The contemporary role of ablative treatment approaches in the management of renal cell carcinoma (RCC): focus on radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), and cryoablation.

    PubMed

    Klatte, Tobias; Kroeger, Nils; Zimmermann, Uwe; Burchardt, Martin; Belldegrun, Arie S; Pantuck, Allan J

    2014-06-01

    Currently, most of renal tumors are small, low grade, with a slow growth rate, a low metastatic potential, and with up to 30 % of these tumors being benign on the final pathology. Moreover, they are often diagnosed in elderly patients with preexisting medical comorbidities in whom the underlying medical conditions may pose a greater risk of death than the small renal mass. Concerns regarding overdiagnosis and overtreatment of patients with indolent small renal tumors have led to an increasing interest in minimally invasive, ablative as an alternative to extirpative interventions for selected patients. To provide an overview about the state of the art in radiofrequency ablation (RFA), high-intensity focused ultrasound, and cryoablation in the clinical management of renal cell carcinoma. A PubMed wide the literature search of was conducted. International consensus panels recommend ablative techniques in patients who are unfit for surgery, who are not considered candidates for or elect against elective surveillance, and who have small renal masses. The most often used techniques are cryoablation and RFA. These ablative techniques offer potentially curative outcomes while conferring several advantages over extirpative surgery, including improved patient procedural tolerance, faster recovery, preservation of renal function, and reduction in the risk of intraoperative and postsurgical complications. While it is likely that outcomes associated with ablative modalities will improve with further advances in technology, their application will expand to more elective indications as longer-term efficacy data become available. Ablative techniques pose a valid treatment option in selected patients.

  17. No-Touch Radiofrequency Ablation: A Comparison of Switching Bipolar and Switching Monopolar Ablation in Ex Vivo Bovine Liver

    PubMed Central

    Chang, Won; Lee, Sang Min; Han, Joon Koo

    2017-01-01

    Objective To evaluate the feasibility, efficiency, and safety of no-touch switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) using ex vivo bovine livers. Materials and Methods A pork loin cube was inserted as a tumor mimicker in the bovine liver block; RFA was performed using the no-touch technique in the SM (group A1; 10 minutes, n = 10, group A2; 15 minutes, n = 10) and SB (group B; 10 minutes, n = 10) modes. The groups were compared based on the creation of confluent necrosis with sufficient safety margins, the dimensions, and distance between the electrode and ablation zone margin (DEM). To evaluate safety, small bowel loops were placed above the liver surface and 30 additional ablations were performed in the same groups. Results Confluent necroses with sufficient safety margins were created in all specimens. SM RFA created significantly larger volumes of ablation compared to SB RFA (all p < 0.001). The DEM of group B was significantly lower than those of groups A1 and A2 (all p < 0.001). Although thermal injury to the small bowel was noted in 90%, 100%, and 30% of the cases in groups A1, A2, and B, respectively, full depth injury was noted only in 60% of group A2 cases. Conclusion The no-touch RFA technique is feasible in both the SB and SM modes; however, SB RFA appears to be more advantageous compared to SM RFA in the creation of an ablation zone while avoiding the unnecessary creation of an adjacent parenchymal ablation zone or adjacent small bowel injuries. PMID:28246508

  18. Ablation of Rotor and Focal Sources Reduces Late Recurrence of Atrial Fibrillation Compared to Trigger Ablation Alone

    PubMed Central

    Narayan, Sanjiv M.; Baykaner, Tina; Clopton, Paul; Schricker, Amir; Lalani, Gautam; Krummen, David E.; Shivkumar, Kalyanam; Miller, John M.

    2014-01-01

    Objectives To determine if ablation that targets patient-specific AF-sustaining substrates (rotors or focal sources) is more durable than trigger ablation alone at preventing late AF recurrences. Background Late recurrence substantially limits the efficacy of pulmonary vein (PV) isolation for AF, and is associated with PV reconnection and the emergence of new triggers. Methods We performed 3 year follow-up of the CONFIRM trial, in which 92 consecutive AF patients (70.7% persistent) underwent novel computational mapping to reveal a median of 2 (IQR 1–2) rotors or focal sources in 97.7% of patients during AF. Ablation comprised source (Focal Impulse and Rotor Modulation, FIRM) then conventional ablation in n=27 (FIRM-guided), and conventional ablation alone in n=65 (FIRM-blinded). Patients were followed with implanted ECG monitors when possible (85.2% FIRM guided, 23.1% FIRM-blinded). Results On 890 days follow-up (median; IQR 224–1563) compared FIRM-blinded therapy, patients receiving FIRM-guided ablation maintained higher freedom from AF after 1.2±0.4 procedures (median 1, IQR 1–1) (77.8% vs 38.5%; p=0.001) and a single procedure (p>0.001), and higher freedom from all atrial arrhythmias (p=0.003). Freedom from AF was higher when ablation directly or coincidentally passed through sources than when it missed sources (p>0.001). CONCLUSIONS FIRM-guided ablation is more durable than conventional trigger-based ablation at preventing 3 year AF recurrence. Future studies should investigate how ablation of patient-specific AF-sustaining rotors and focal sources alters the natural history of arrhythmia recurrence. PMID:24632280

  19. Comparison of remote magnetic navigation ablation and manual ablation of idiopathic ventricular arrhythmia after failed manual ablation.

    PubMed

    Kawamura, Mitsuharu; Scheinman, Melvin M; Tseng, Zian H; Lee, Byron K; Marcus, Gregory M; Badhwar, Nitish

    2017-01-01

    Catheter ablation for idiopathic ventricular arrhythmia (VA) is effective and safe, but efficacy is frequently limited due to an epicardial origin and difficult anatomy. The remote magnetic navigation (RMN) catheter has a flexible catheter design allowing access to difficult anatomy. We describe the efficacy of the RMN for ablation of idiopathic VA after failed manual ablation. Among 235 patients with idiopathic VA referred for catheter ablation, we identified 51 patients who were referred for repeat ablation after a failed manual ablation. We analyzed the clinical characteristics, including the successful ablation site and findings at electrophysiology study, in repeat procedures conducted using RMN as compared with manual ablation. Among these patients, 22 (43 %) underwent repeat ablation with the RMN and 29 (57 %) underwent repeat ablation with a manual ablation. Overall, successful ablation rate was significantly higher using RMN as compared with manual ablation (91 vs. 69 %, P = 0.02). Fluoroscopy time in the RMN was 17 ± 12 min as compared with 43 ± 18 min in the manual ablation (P = 0.009). Successful ablation rate in the posterior right ventricular outflow tract (RVOT) plus posterior-tricuspid annulus was higher with RMN as compared with manual ablation (92 vs. 50 %, P = 0.03). Neither groups exhibited any major complications. The RMN is more effective in selected patients with recurrent idiopathic VA after failed manual ablation and is associated with less fluoroscopy time. The RMN catheters have a flexible design enabling them to access otherwise difficult anatomy including the posterior tricuspid annulus and posterior RVOT.

  20. Comparison of Solomon technique with selective laser ablation for twin-twin transfusion syndrome: a systematic review.

    PubMed

    Dhillon, R K; Hillman, S C; Pounds, R; Morris, R K; Kilby, M D

    2015-11-01

    To compare the Solomon and selective techniques for fetoscopic laser ablation (FLA) for the treatment of twin-twin transfusion syndrome (TTTS) in monochorionic-diamniotic twin pregnancies. This was a systematic review conducted in accordance with the PRISMA statement. Electronic searches were performed for relevant citations published from inception to September 2014. Selected studies included pregnancies undergoing FLA for TTTS that reported on recurrence of TTTS, occurrence of twin anemia-polycythemia sequence (TAPS) or survival. From 270 possible citations, three studies were included, two cohort studies and one randomized controlled trial (RCT), which directly compared the Solomon and selective techniques for FLA. The odds ratios (OR) of recurrent TTTS when using the Solomon vs the selective technique in the two cohort studies (n = 249) were 0.30 (95% CI, 0.00-4.46) and 0.45 (95% CI, 0.07-2.20). The RCT (n = 274) demonstrated a statistically significant reduction in risk of recurrent TTTS with the Solomon technique (OR, 0.21 (95% CI, 0.04-0.98); P = 0.03). The ORs for the development of TAPS following the Solomon and the selective techniques were 0.20 (95% CI, 0.00-2.46) and 0.61 (95% CI, 0.05-5.53) in the cohort studies and 0.16 (95% CI, 0.05-0.49) in the RCT, with statistically significant differences for the RCT only (P < 0.001). Observational evidence suggested overall better survival with the Solomon technique, which was statistically significant for survival of at least one twin. The RCT did not demonstrate a significant difference in survival between the two techniques, most probably owing to the small sample size and lack of power. This systematic review of observational, comparative cohort and RCT data suggests a trend towards a reduction in TAPS and recurrent TTTS and an increase in twin survival, with no increase in the occurrence of complications or adverse events, when using the Solomon compared to the selective technique for the treatment of TTTS

  1. Development of Naphthalene PLIF for Visualizing Ablation Products From a Space Capsule Heat Shield

    NASA Technical Reports Server (NTRS)

    Combs, C. S.; Clemens, N. T.; Danehy, P. M.

    2014-01-01

    The Orion Multi-Purpose Crew Vehicle (MPCV) will use an ablative heat shield. To better design this heat shield and others that will undergo planetary entry, an improved understanding of the ablation process would be beneficial. Here, a technique developed at The University of Texas at Austin that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to enable visualization of the ablation products in a hypersonic flow is applied. Although high-temperature ablation is difficult and expensive to recreate in a laboratory environment, low-temperature sublimation creates a limited physics problem that can be used to explore ablation-product transport in a hypersonic flow-field. In the current work, a subscale capsule reentry vehicle model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel. The PLIF technique provides images of the spatial distribution of sublimated naphthalene in the heat-shield boundary layer, separated shear layer, and backshell recirculation region. Visualizations of the capsule shear layer using both naphthalene PLIF and Schlieren imaging compared favorably. PLIF images have shown high concentrations of naphthalene in the capsule separated flow region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure. It was shown that, in general, the capsule shear layer appears to be more unsteady at lower angels of attack. The PLIF images demonstrated that during a wind tunnel run, as the model heated up, the rate of naphthalene ablation increased, since the PLIF signal increased steadily over the course of a run. Additionally, the shear layer became increasingly unsteady over the course of a wind tunnel run, likely because of increased surface roughness but also possibly because of the increased blowing. Regions with a relatively low concentration of naphthalene were also identified in the capsule backshell

  2. Microwave Ablation of Porcine Kidneys in vivo: Effect of two Different Ablation Modes ('Temperature Control' and 'Power Control') on Procedural Outcome

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sommer, C. M., E-mail: christof.sommer@med.uni-heidelberg.de; Arnegger, F.; Koch, V.

    2012-06-15

    Purpose: This study was designed to analyze the effect of two different ablation modes ('temperature control' and 'power control') of a microwave system on procedural outcome in porcine kidneys in vivo. Methods: A commercially available microwave system (Avecure Microwave Generator; MedWaves, San Diego, CA) was used. The system offers the possibility to ablate with two different ablation modes: temperature control and power control. Thirty-two microwave ablations were performed in 16 kidneys of 8 pigs. In each animal, one kidney was ablated twice by applying temperature control (ablation duration set point at 60 s, ablation temperature set point at 96 Degree-Signmore » C, automatic power set point; group I). The other kidney was ablated twice by applying power control (ablation duration set point at 60 s, ablation temperature set point at 96 Degree-Sign C, ablation power set point at 24 W; group II). Procedural outcome was analyzed: (1) technical success (e.g., system failures, duration of the ablation cycle), and (2) ablation geometry (e.g., long axis diameter, short axis diameter, and circularity). Results: System failures occurred in 0% in group I and 13% in group II. Duration of the ablation cycle was 60 {+-} 0 s in group I and 102 {+-} 21 s in group II. Long axis diameter was 20.3 {+-} 4.6 mm in group I and 19.8 {+-} 3.5 mm in group II (not significant (NS)). Short axis diameter was 10.3 {+-} 2 mm in group I and 10.5 {+-} 2.4 mm in group II (NS). Circularity was 0.5 {+-} 0.1 in group I and 0.5 {+-} 0.1 in group II (NS). Conclusions: Microwave ablations performed with temperature control showed fewer system failures and were finished faster. Both ablation modes demonstrated no significant differences with respect to ablation geometry.« less

  3. 2D elemental mapping of sections of human kidney stones using laser ablation inductively-coupled plasma-mass spectrometry: Possibilities and limitations

    NASA Astrophysics Data System (ADS)

    Vašinová Galiová, Michaela; Čopjaková, Renata; Škoda, Radek; Štěpánková, Kateřina; Vaňková, Michaela; Kuta, Jan; Prokeš, Lubomír; Kynický, Jindřich; Kanický, Viktor

    2014-10-01

    A 213 nm Nd:YAG-based laser ablation (LA) system coupled to quadrupole-based inductively coupled plasma-mass spectrometer and an ArF* excimer-based LA-system coupled to a double-focusing sector field inductively coupled plasma-mass spectrometer were employed to study the spatial distribution of various elements in kidney stones (uroliths). Sections of the surfaces of uroliths were ablated according to line patterns to investigate the elemental profiles for the different urolith growth zones. This exploratory study was mainly focused on the distinguishing of the main constituents of urinary calculus fragments by means of LA-ICP-mass spectrometry. Changes in the ablation rate for oxalate and phosphate phases related to matrix density and hardness are discussed. Elemental association was investigated on the basis of 2D mapping. The possibility of using NIST SRM 1486 Bone Meal as an external standard for calibration was tested. It is shown that LA-ICP-MS is helpful for determination of the mineralogical composition and size of all phases within the analyzed surface area, for tracing down elemental associations and for documenting the elemental content of urinary stones. LA-ICP-MS results (elemental contents and maps) are compared to those obtained with electron microprobe analysis and solution analysis ICP-MS.

  4. A New Radiofrequency Ablation Procedure to Treat Sacroiliac Joint Pain.

    PubMed

    Cheng, Jianguo; Chen, See Loong; Zimmerman, Nicole; Dalton, Jarrod E; LaSalle, Garret; Rosenquist, Richard

    2016-01-01

    Low back pain may arise from disorders of the sacroiliac joint in up to 30% of patients. Radiofrequency ablation (RFA) of the nerves innervating the sacroiliac joint has been shown to be a safe and efficacious strategy. We aimed to develop a new RFA technique to relieve low back pain secondary to sacroiliac joint disorders. Methodology development with validation through prospective observational non-randomized trial (PONRT). Academic multidisciplinary health care system, Ohio, USA. We devised a guide-block to facilitate accurate placement of multiple electrodes to simultaneously ablate the L5 dorsal ramus and lateral branches of the S1, S2, and S3 dorsal rami. This was achieved by bipolar radiofrequency ablation (b-RFA) to create a strip lesion from the lateral border of the base of the sacral superior articular process (L5-S1 facet joint) to the lateral border of the S3 sacral foramen. We applied this technique in 31 consecutive patients and compared the operating time, x-ray exposure time and dose, and clinical outcomes with patients (n = 62) who have been treated with the cooled radiofrequency technique. Patients' level of pain relief was reported as < 50%, 50 - 80%, and > 80% pain relief at one, 3, 6, and 12 months after the procedure. The relationship between RFA technique and duration of pain relief was evaluated using interval-censored multivariable Cox regression. The new technique allowed reduction of operating time by more than 50%, x-ray exposure time and dose by more than 80%, and cost by more than $1,000 per case. The percent of patients who achieved > 50% pain reduction was significantly higher in the b-RFA group at 3, 6, and 12 months follow-up, compared to the cooled radiofrequency group. No complications were observed in either group. Although the major confounding factors were taken into account in the analysis, use of historical controls does not balance observed and unobserved potential confounding variables between groups so that the reported

  5. Evolution of the ablation region after magnetic resonance-guided high-intensity focused ultrasound ablation in a Vx2 tumor model.

    PubMed

    Wijlemans, Joost W; Deckers, Roel; van den Bosch, Maurice A A J; Seinstra, Beatrijs A; van Stralen, Marijn; van Diest, Paul J; Moonen, Chrit T W; Bartels, Lambertus W

    2013-06-01

    Volumetric magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU) is a completely noninvasive image-guided thermal ablation technique. Recently, there has been growing interest in the use of MR-HIFU for noninvasive ablation of malignant tumors. Of particular interest for noninvasive ablation of malignant tumors is reliable treatment monitoring and evaluation of response. At this point, there is limited evidence on the evolution of the ablation region after MR-HIFU treatment. The purpose of the present study was to comprehensively characterize the evolution of the ablation region after volumetric MR-HIFU ablation in a Vx2 tumor model using MR imaging, MR temperature data, and histological data. Vx2 tumors in the hind limb muscle of New Zealand White rabbits (n = 30) were ablated using a clinical MR-HIFU system. Twenty-four animals were available for analyses. Magnetic resonance imaging was performed before and immediately after ablation; MR temperature mapping was performed during the ablation. The animals were distributed over 7 groups with different follow-up lengths. Depending on the group, animals were reimaged and then killed on day 0, 1, 3, 7, 14, 21, or 28 after ablation. For all time points, the size of nonperfused areas (NPAs) on contrast-enhanced T1-weighted (CE-T1-w) images was compared with lethal thermal dose areas (ie, the tissue area that received a thermal dose of 240 equivalent minutes or greater [EM] at 43°C) and with the necrotic tissue areas on histology sections. The NPA on CE-T1-w imaging showed an increase in median size from 266 ± 148 to 392 ± 178 mm(2) during the first day and to 343 ± 170 mm(2) on day 3, followed by a gradual decrease to 113 ± 103 mm(2) on day 28. Immediately after ablation, the NPA was 1.6 ± 1.4 times larger than the area that received a thermal dose of 240 EM or greater in all animals. The median size of the necrotic area on histology was 1.7 ± 0.4 times larger than the NPA immediately after

  6. Hard tissue ablation with a spray-assisted mid-IR laser

    NASA Astrophysics Data System (ADS)

    Kang, H. W.; Rizoiu, I.; Welch, A. J.

    2007-12-01

    The objective of this study was to understand the dominant mechanism(s) for dental enamel ablation with the application of water spray. A free-running Er,Cr:YSGG (yttrium, scandium, gallium, garnet) laser was used to ablate human enamel tissue at various radiant exposures. During dental ablation, distilled water was sprayed on the sample surface, and these results were compared to ablation without a spray (dry ablation). In order to identify dominant ablation mechanisms, transient acoustic waves were compared to ablation thresholds and the volume of material removed. The ablation profile and depth were measured using optical coherence tomography (OCT). Irregular surface modification, charring and peripheral cracks were associated with dry ablation, whereas craters for spray samples were relatively clean without thermal damage. In spite of a 60% higher ablation threshold for spray associated irradiations owing to water absorption, acoustic peak pressures were six times higher and ablation volume was up to a factor of 2 larger compared to dry ablation. The enhanced pressure and ablation performance of the spray-assisted process was the result of rapid water vaporization, material ejection with recoil stress, interstitial water explosion and possibly liquid-jet formation. With water cooling and abrasive/disruptive mechanical effects, the spray ablation can be a safe and efficient modality for dental treatment.

  7. Possibilities of LA-ICP-MS technique for the spatial elemental analysis of the recent fish scales: Line scan vs. depth profiling

    NASA Astrophysics Data System (ADS)

    Holá, Markéta; Kalvoda, Jiří; Nováková, Hana; Škoda, Radek; Kanický, Viktor

    2011-01-01

    LA-ICP-MS and solution based ICP-MS in combination with electron microprobe are presented as a method for the determination of the elemental spatial distribution in fish scales which represent an example of a heterogeneous layered bone structure. Two different LA-ICP-MS techniques were tested on recent common carp ( Cyprinus carpio) scales: A line scan through the whole fish scale perpendicular to the growth rings. The ablation crater of 55 μm width and 50 μm depth allowed analysis of the elemental distribution in the external layer. Suitable ablation conditions providing a deeper ablation crater gave average values from the external HAP layer and the collagen basal plate. Depth profiling using spot analysis was tested in fish scales for the first time. Spot analysis allows information to be obtained about the depth profile of the elements at the selected position on the sample. The combination of all mentioned laser ablation techniques provides complete information about the elemental distribution in the fish scale samples. The results were compared with the solution based ICP-MS and EMP analyses. The fact that the results of depth profiling are in a good agreement both with EMP and PIXE results and, with the assumed ways of incorporation of the studied elements in the HAP structure, suggests a very good potential for this method.

  8. [Thoracoscopic, epicardial ablation of atrial fibrillation using the COBRA Fusion system as the first part of hybrid ablation].

    PubMed

    Budera, P; Osmančík, P; Talavera, D; Fojt, R; Kraupnerová, A; Žďárská, J; Vaněk, T; Straka, Z

    2017-01-01

    Treatment of persistent and long-standing persistent atrial fibrillation is not successfully managed by methods of catheter ablation or pharmacotherapy. Hybrid ablation (i.e. combination of minimally invasive surgical ablation, followed by electrophysiological assessment and subsequent endocardial catheter ablation to complete the entire intended procedure) presents an ever more used and very promising treatment method. Patients underwent thoracoscopic ablation of pulmonary veins and posterior wall of the left atrium (the box-lesion) with use of the COBRA Fusion catheter; thoracoscopic occlusion of the left atrial appendage using the AtriClip system was also done in later patients. After 23 months, electrophysiological assessment and catheter ablation followed. In this article we summarize a strategy of the surgical part of the hybrid procedure performed in our centre. We describe the surgery itself (including possible periprocedural complications) and we also present our short-term results, especially with respect to subsequent electrophysiological findings. Data of the first 51 patients were analyzed. The first 25 patients underwent unilateral ablation; the mean time of surgery was 102 min. Subsequent 26 patients underwent the bilateral procedure with the mean surgery time of 160 min. Serious complications included 1 stroke, 1 phrenic nerve palsy and 2 surgical re-explorations for bleeding. After 1 month, 65% of patients showed sinus rhythm. The box-lesion was found complete during electrophysiological assessment in 38% of patients and after catheter ablation, 96% of patients were discharged in sinus rhythm. The surgical part of the hybrid procedure with use of the minimally invasive approach and the COBRA Fusion catheter is a well-feasible method with a low number of periprocedural complications. For electrophysiologists, it provides a very good basis for successful completion of the hybrid ablation.Key words: atrial fibrillation hybrid ablation - thoracoscopy

  9. Fracture in Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Agrawal, Parul; Chavez-Garcia, Jose; Pham, John

    2013-01-01

    This paper describes the development of a novel technique to understand the failure mechanisms inside thermal protection materials. The focus of this research is on the class of materials known as phenolic impregnated carbon ablators. It has successfully flown on the Stardust spacecraft and is the thermal protection system material chosen for the Mars Science Laboratory and SpaceX Dragon spacecraft. Although it has good thermal properties, structurally, it is a weak material. To understand failure mechanisms in carbon ablators, fracture tests were performed on FiberForm(Registered TradeMark) (precursor), virgin, and charred ablator materials. Several samples of these materials were tested to investigate failure mechanisms at a microstructural scale. Stress-strain data were obtained simultaneously to estimate the tensile strength and toughness. It was observed that cracks initiated and grew in the FiberForm when a critical stress limit was reached such that the carbon fibers separated from the binder. However, both for virgin and charred carbon ablators, crack initiation and growth occurred in the matrix (phenolic) phase. Both virgin and charred carbon ablators showed greater strength values compared with FiberForm samples, confirming that the presence of the porous matrix helps in absorbing the fracture energy.

  10. Global Endometrial Ablation in the Presence of Essure® Microinserts

    PubMed Central

    Aldape, Diana; Chudnoff, Scott G; Levie, Mark D

    2013-01-01

    Abnormal uterine bleeding (AUB) affects 30% of women at some time during their reproductive years and is one of the most common reasons a woman sees a gynecologist. Many women are turning to endometrial ablation to manage their AUB. This article reviews the data relating to the available endometrial ablation techniques performed with hysteroscopic sterilization, and focuses on data from patients who had Essure® (Conceptus, San Carlos, CA) coils placed prior to performance of endometrial ablation. Reviewed specifically are data regarding safety and efficacy of these two procedures when combined. Data submitted to the US Food and Drug Administration for the three devices currently approved are reviewed, as well as all published case series. Articles included were selected based on a PubMed search for endometrial ablation (also using the brand names of the different techniques currently available), hysteroscopic sterilization, and Essure. PMID:24358407

  11. New Possibilities for the Accurate in Situ Determination of Chalcophile and Siderophile Trace Elements by Laser Ablation Collision and Reaction Cell ICP-MS

    NASA Astrophysics Data System (ADS)

    Mason, P. R.

    2004-05-01

    Our knowledge of how chalcophile and siderophile elements partition in minerals is limited, mainly due to the lack of suitable techniques for their accurate in situ determination. Host minerals (e.g. sulphides) are typically of small size (<30 μ m) and highly heterogeneous in composition, requiring analysis of high spatial resolution. Concentrations of chalcophile elements in silicates and oxides are low (sub μ gg-1) and thus challenging to measure. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), offering high sensitivity and good spatial resolution (10-100 μ m) is thus highly suited for this purpose. Unfortunately, the widespread use of this technique has been limited by enhanced problems specific to chalcophile and siderophile elements. These include inaccuracy due to the presence of spectral interferences, elemental fractionation during ablation/ionization and the lack of suitable calibration standards. Polyatomic spectral interferences, present either as a background component (e.g. O2+, ArAr+) or based around the recombination of matrix elements with argon (e.g. ArS+, ArNi+) hinder accurate analysis. These depend upon the relative concentrations of major matrix components and trace elements to be measured and are significant in many relevant minerals (e.g. sulphides). The use of a collision and reaction cells in ICP-MS is a new method for selective interference attenuation, significantly improving detection limits for elements such as Fe, S and Se by between 1 and 4 orders of magnitude. ArNi+ and ArCu+ interferences in sulphides can be attenuated by at least an order of magnitude leading to improved accuracy for the measurement of the Platinum Group elements Rh and Ru. Sulphur isotopes can be measured interference-free at m/z=32 and 34 by eliminating background O2+. These improvements open up new possibilities for the use of LA-ICP-MS in trace element and isotopic studies at the lowest concentration levels or where sample

  12. Sampling modulation technique in radio-frequency helium glow discharge emission source by use of pulsed laser ablation.

    PubMed

    Naeem, Tariq Mahmood; Matsuta, Hideyuki; Wagatsuma, Kazuaki

    2004-05-01

    An emission excitation source comprising a high-frequency diode-pumped Q-switched Nd:YAG laser and a radio-frequency powered glow discharge lamp is proposed. In this system sample atoms ablated by the laser irradiation are introduced into the lamp chamber and subsequently excited by the helium glow discharge plasma. The pulsed operation of the laser can produce a cyclic variation in the emission intensities of the sample atoms whereas the plasma gas species emit the radiation continuously. The salient feature of the proposed technique is the selective detection of the laser modulation signal from the rest of the continuous background emissions, which can be achieved with the phase sensitive detection of the lock-in amplifier. The arrangement may be used to estimate the emission intensity of the laser ablated atom, free from the interference of other species present in the plasma. The experiments were conducted with a 13.56 MHz radio-frequency (rf) generator operated at 80 W power to produce plasma and the laser at a wavelength of 1064 nm (pulse duration:34 ns, repetition rate:7 kHz and average pulse energy of about 0.36 mJ) was employed for sample ablation. The measurements resulted in almost complete removal of nitrogen molecular bands (N(2)(+) 391.44 nm). Considerable reduction (about 75%) in the emission intensity of a carbon atomic line (C I 193.03 nm) was also observed.

  13. Miniaturization of Microwave Ablation Antennas

    NASA Astrophysics Data System (ADS)

    Luyen, Hung

    Microwave ablation (MWA) is a promising minimally invasive technique for the treatment of various types of cancers as well as non-oncological diseases. In MWA, an interstitial antenna is typically used to deliver microwave energy to the diseased tissue and heat it up to lethal temperature levels that induce cell death. The desired characteristics of the interstitial antenna include a narrow diameter to minimize invasiveness of the treatment, a low input reflection coefficient at the operating frequency, and a localized heating zone. Most interstitial MWA antennas are fed by coaxial cables and designed for operation at either 915 MHz or 2.45 GHz. Coax-fed MWA antennas are commonly equipped with coaxial baluns to achieve localized heating. However, the conventional implementation of coaxial baluns increases the overall diameters of the antennas and therefore make them more invasive. It is highly desirable to develop less invasive antennas with shorter active lengths and smaller diameters for MWA applications. In this work, we demonstrate the feasibility of using higher frequency microwaves for tissue ablation and present several techniques for decreasing diameters of MWA antennas. First, we investigated MWA at higher frequencies by conducting numerical and experimental studies to compare ablation performance at 10 GHz and 1.9 GHz. Simulation and ex vivo ablation experiment results demonstrate comparable ablation zone dimensions achieved at these two frequencies. Operating at higher frequencies enables interstitial antennas with shorter active lengths. This can be combined with smaller-diameter antenna designs to create less invasive applicators or allow integration of multiple radiating elements on a single applicator to have better control and customization of the heating patterns. Additionally, we present three different coax-fed antenna designs and a non-coaxial-based balanced antenna that have smaller-diameter configurations than conventional coax-fed balun

  14. Inertial confinement fusion ablator physics experiments on Saturn and Nova

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Olson, R.E.; Porter, J.L.; Chandler, G.A.

    1997-05-01

    The Saturn pulsed power accelerator [R. B. Spielman {ital et al.}, in {ital Proceedings of the 2nd International Conference on Dense} Z-{ital pinches}, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3] at Sandia National Laboratories (SNL) and the Nova laser [J. T. Hunt and D. R. Speck, Opt. Eng. {bold 28}, 461 (1989)] at Lawrence Livermore National Laboratory (LLNL) have been used to explore techniques for studying the behavior of ablator material in x-ray radiation environments comparable in magnitude, spectrum, and duration to those thatmore » would be experienced in National Ignition Facility (NIF) hohlraums [J. D. Lindl, Phys. Plasmas {bold 2}, 3933 (1995)]. The large x-ray outputs available from the Saturn pulsed-power-driven z pinch have enabled us to drive hohlraums of full NIF ignition scale size at radiation temperatures and time scales comparable to those required for the low-power foot pulse of an ignition capsule. The high-intensity drives available in the Nova laser have allowed us to study capsule ablator physics in smaller-scale hohlraums at radiation temperatures and time scales relevant to the peak power pulse for an ignition capsule. Taken together, these experiments have pointed the way to possible techniques for testing radiation-hydrodynamics code predictions of radiation flow, opacity, equation of state, and ablator shock velocity over the range of radiation environments that will be encountered in a NIF hohlraum. {copyright} {ital 1997 American Institute of Physics.}« less

  15. Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron.

    PubMed

    Helber, Bernd; Chazot, Olivier; Hubin, Annick; Magin, Thierry E

    2016-06-09

    Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties. The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale

  16. Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

    PubMed Central

    Helber, Bernd; Chazot, Olivier; Hubin, Annick; Magin, Thierry E.

    2016-01-01

    Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties. The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale

  17. Ultrafast laser ablation for targeted atherosclerotic plaque removal

    NASA Astrophysics Data System (ADS)

    Lanvin, Thomas; Conkey, Donald B.; Descloux, Laurent; Frobert, Aurelien; Valentin, Jeremy; Goy, Jean-Jacques; Cook, Stéphane; Giraud, Marie-Noelle; Psaltis, Demetri

    2015-07-01

    Coronary artery disease, the main cause of heart disease, develops as immune cells and lipids accumulate into plaques within the coronary arterial wall. As a plaque grows, the tissue layer (fibrous cap) separating it from the blood flow becomes thinner and increasingly susceptible to rupturing and causing a potentially lethal thrombosis. The stabilization and/or treatment of atherosclerotic plaque is required to prevent rupturing and remains an unsolved medical problem. Here we show for the first time targeted, subsurface ablation of atherosclerotic plaque using ultrafast laser pulses. Excised atherosclerotic mouse aortas were ablated with ultrafast near-infrared (NIR) laser pulses. The physical damage was characterized with histological sections of the ablated atherosclerotic arteries from six different mice. The ultrafast ablation system was integrated with optical coherence tomography (OCT) imaging for plaque-specific targeting and monitoring of the resulting ablation volume. We find that ultrafast ablation of plaque just below the surface is possible without causing damage to the fibrous cap, which indicates the potential use of ultrafast ablation for subsurface atherosclerotic plaque removal. We further demonstrate ex vivo subsurface ablation of a plaque volume through a catheter device with the high-energy ultrafast pulse delivered via hollow-core photonic crystal fiber.

  18. Treatment Planning and Image Guidance for Radiofrequency Ablations of Large Tumors

    PubMed Central

    Ren, Hongliang; Campos-Nanez, Enrique; Yaniv, Ziv; Banovac, Filip; Abeledo, Hernan; Hata, Nobuhiko; Cleary, Kevin

    2014-01-01

    This article addresses the two key challenges in computer-assisted percutaneous tumor ablation: planning multiple overlapping ablations for large tumors while avoiding critical structures, and executing the prescribed plan. Towards semi-automatic treatment planning for image-guided surgical interventions, we develop a systematic approach to the needle-based ablation placement task, ranging from pre-operative planning algorithms to an intra-operative execution platform. The planning system incorporates clinical constraints on ablations and trajectories using a multiple objective optimization formulation, which consists of optimal path selection and ablation coverage optimization based on integer programming. The system implementation is presented and validated in phantom studies and on an animal model. The presented system can potentially be further extended for other ablation techniques such as cryotherapy. PMID:24235279

  19. Preparation of starch stabilized silver nanoparticles with spatial self-phase modulation properties by laser ablation technique

    NASA Astrophysics Data System (ADS)

    Zamiri, Reza; Azmi, B. Z.; Darroudi, Majid; Sadrolhosseini, Amir R.; Husin, M. S.; Zaidan, A. W.; Mahdi, M. A.

    2011-01-01

    Silver nanoparticles inside the starch solution have been successfully fabricated by laser ablation of a silver plate immersed in starch solution. The ablation has been done using a Q-switched Nd:YAG laser at 10 Hz repetition rate. The starch solution allows for the formation of silver nanoparticles with uniform particle diameters and well dispersed. The ablation was performed at different time durations to study the influence of the laser ablation time on efficiency of particle formation and sizes. The Spatial Self-phase modulation phenomena which can determine the nonlinear optical property of the samples were also investigated for starch solutions containing silver nanoparticles.

  20. Observing laser ablation dynamics with sub-picosecond temporal resolution

    NASA Astrophysics Data System (ADS)

    Tani, Shuntaro; Kobayashi, Yohei

    2017-04-01

    Laser ablation is one of the most fundamental processes in laser processing, and the understanding of its dynamics is of key importance for controlling and manipulating the outcome. In this study, we propose a novel way of observing the dynamics in the time domain using an electro-optic sampling technique. We found that an electromagnetic field was emitted during the laser ablation process and that the amplitude of the emission was closely correlated with the ablated volume. From the temporal profile of the electromagnetic field, we analyzed the motion of charged particles with subpicosecond temporal resolution. The proposed method can provide new access to observing laser ablation dynamics and thus open a new way to optimize the laser processing.

  1. Left Atrial Anatomy Relevant to Catheter Ablation

    PubMed Central

    Sánchez-Quintana, Damián; Cabrera, José Angel; Saremi, Farhood

    2014-01-01

    The rapid development of interventional procedures for the treatment of arrhythmias in humans, especially the use of catheter ablation techniques, has renewed interest in cardiac anatomy. Although the substrates of atrial fibrillation (AF), its initiation and maintenance, remain to be fully elucidated, catheter ablation in the left atrium (LA) has become a common therapeutic option for patients with this arrhythmia. Using ablation catheters, various isolation lines and focal targets are created, the majority of which are based on gross anatomical, electroanatomical, and myoarchitectual patterns of the left atrial wall. Our aim was therefore to review the gross morphological and architectural features of the LA and their relations to extracardiac structures. The latter have also become relevant because extracardiac complications of AF ablation can occur, due to injuries to the phrenic and vagal plexus nerves, adjacent coronary arteries, or the esophageal wall causing devastating consequences. PMID:25057427

  2. Image-Guided Spinal Ablation: A Review

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tsoumakidou, Georgia, E-mail: gtsoumakidou@yahoo.com; Koch, Guillaume, E-mail: guillaume.koch@chru-strasbourg.fr; Caudrelier, Jean, E-mail: jean.caudrelier@chru-strasbourg.fr

    2016-09-15

    The image-guided thermal ablation procedures can be used to treat a variety of benign and malignant spinal tumours. Small size osteoid osteoma can be treated with laser or radiofrequency. Larger tumours (osteoblastoma, aneurysmal bone cyst and metastasis) can be addressed with radiofrequency or cryoablation. Results on the literature of spinal microwave ablation are scarce, and thus it should be used with caution. A distinct advantage of cryoablation is the ability to monitor the ice-ball by intermittent CT or MRI. The different thermal insulation, temperature and electrophysiological monitoring techniques should be applied. Cautious pre-procedural planning and intermittent intra-procedural monitoring of themore » ablation zone can help reduce neural complications. Tumour histology, patient clinical-functional status and life-expectancy should define the most efficient and least disabling treatment option.« less

  3. Percutaneous thermal ablation of lung tumors - Radiofrequency, microwave and cryotherapy: Where are we going?

    PubMed

    Palussière, J; Catena, V; Buy, X

    2017-09-01

    Main indications of percutaneous pulmonary thermal ablation are early stage non-small cell lung carcinoma (NSCLC) for patients who are not amenable to surgery and slow-evolving localized metastatic disease, either spontaneous or following a general treatment. Radiofrequency ablation (RFA) is the most evaluated technique. This technique offers a local control rate ranging between 80 and 90% for tumors <3cm in diameter. Other more recently used ablation techniques such as microwaves and cryotherapy could overcome some limitations of RFA. One common characteristic of these techniques is an excellent tolerance with very few complications. This article reviews the differences between these techniques when applied to lung tumors, indications, results and complications. Future potential associations with immunotherapy will be discussed. Copyright © 2017. Published by Elsevier Masson SAS.

  4. Artificial ascites and pneumoperitoneum to facilitate thermal ablation of liver tumors: a pictorial essay.

    PubMed

    Bhagavatula, Sharath K; Chick, Jeffrey F B; Chauhan, Nikunj R; Shyn, Paul B

    2017-02-01

    Image-guided percutaneous thermal ablation is increasingly utilized in the treatment of hepatic malignancies. Peripherally located hepatic tumors can be difficult to access or located adjacent to critical structures that can be injured. As a result, ablation of peripheral tumors may be avoided or may be performed too cautiously, leading to inadequate ablation coverage. In these cases, separating the tumor from adjacent critical structures can increase the efficacy and safety of procedures. Artificial ascites and artificial pneumoperitoneum are techniques that utilize fluid and gas, respectively, to insulate critical structures from the thermal ablation zone. Induction of artificial ascites and artificial pneumoperitoneum can enable complete ablation of otherwise inaccessible hepatic tumors, improve tumor visualization, minimize unintended thermal injury to surrounding organs, and reduce post-procedural pain. This pictorial essay illustrates and discusses the proper technique and clinical considerations for successful artificial ascites and pneumoperitoneum creation to facilitate safe peripheral hepatic tumor ablation.

  5. Laser ablated hydantoin: A high resolution rotational study.

    PubMed

    Alonso, Elena R; Kolesniková, Lucie; Alonso, José L

    2017-09-28

    Laser ablation techniques coupled with broadband and narrowband Fourier transform microwave spectroscopies have allowed the high resolution rotational study of solid hydantoin, an important target in astrochemistry as a possible precursor of glycine. The complicated hyperfine structure arising from the presence of two 14 N nuclei in non-equivalent positions has been resolved and interpreted in terms of the nuclear quadrupole coupling interactions. The results reported in this work provide a solid base for the interstellar searches of hydantoin in the astrophysical surveys. The values of the nuclear quadrupole coupling constants have been also discussed in terms of the electronic environment around the respective nitrogen atom.

  6. Trace contaminant determination in fish scale by laser-ablation technique

    NASA Astrophysics Data System (ADS)

    Lee, Ida; Coutant, C. C.; Arakawa, E. T.

    1993-10-01

    Laser ablation on rings of fish scale has been used to analyze the historical accumulation of polychlorinated biphenyls (PCB) in striped bass in the Watts Bar Reservoir. Rings on a fish scale grow in a pattern that forms a record of the fish's chemical intake. In conjunction with the migration patterns of fish monitored by ecologists, relative PCB concentrations in the seasonal rings of fish scale can be used to study the PCB distribution in the reservoir. In this study, a tightly-focused laser beam from a XeCl excimer laser was used to ablate and ionize a small portion of a fish scale placed in a vacuum chamber. The ions were identified and quantified by a time-of-flight mass spectrometer. Studies of this type can provide valuable information for the Department of Energy (DOE) off-site clean-up efforts as well as identifying the impacts of other sources to local aquatic populations.

  7. Femtosecond laser lithotripsy: feasibility and ablation mechanism.

    PubMed

    Qiu, Jinze; Teichman, Joel M H; Wang, Tianyi; Neev, Joseph; Glickman, Randolph D; Chan, Kin Foong; Milner, Thomas E

    2010-01-01

    Light emitted from a femtosecond laser is capable of plasma-induced ablation of various materials. We tested the feasibility of utilizing femtosecond-pulsed laser radiation (lambda=800 nm, 140 fs, 0.9 mJ/pulse) for ablation of urinary calculi. Ablation craters were observed in human calculi of greater than 90% calcium oxalate monohydrate (COM), cystine (CYST), or magnesium ammonium phosphate hexahydrate (MAPH). Largest crater volumes were achieved on CYST stones, among the most difficult stones to fragment using Holmium:YAG (Ho:YAG) lithotripsy. Diameter of debris was characterized using optical microscopy and found to be less than 20 microm, substantially smaller than that produced by long-pulsed Ho:YAG ablation. Stone retropulsion, monitored by a high-speed camera system with a spatial resolution of 15 microm, was negligible for stones with mass as small as 0.06 g. Peak shock wave pressures were less than 2 bars, measured by a polyvinylidene fluoride (PVDF) needle hydrophone. Ablation dynamics were visualized and characterized with pump-probe imaging and fast flash photography and correlated to shock wave pressures. Because femtosecond-pulsed laser ablates urinary calculi of soft and hard compositions, with micron-sized debris, negligible stone retropulsion, and small shock wave pressures, we conclude that the approach is a promising candidate technique for lithotripsy.

  8. Catheter ablation as a treatment of atrioventricular block.

    PubMed

    Tuohy, Stephen; Saliba, Walid; Pai, Manjunath; Tchou, Patrick

    2018-01-01

    Symptomatic second-degree atrioventricular (AV) block is typically treated by implantation of a pacemaker. An otherwise healthy AV conduction system can nevertheless develop AV block due to interference from junctional extrasystoles. When present with a high burden, these can produce debilitating symptoms from AV block despite an underlying normal AV node and His-Purkinje system properties. The purpose of this study was to describe a catheter ablation approach for alleviating symptomatic AV block due to a ventricular nodal pathway interfering with AV conduction. Common clinical monitoring techniques such as Holter and event recorders were used. Standard electrophysiological study techniques using multipolar recording and ablation catheters were utilized during procedures. A 55-year-old woman presented with highly symptomatic, high-burden second-degree AV block due to concealed and manifest junctional premature beats. Electrophysiological characteristics indicated interference of AV conduction due to a concealed ventricular nodal pathway as the cause of the AV block. The patient's AV nodal and His-Purkinje system conduction characteristics were otherwise normal. Radiofrequency catheter ablation of the pathway was successful in restoring normal AV conduction and eliminating her clinical symptoms. Pathways inserting into the AV junction can interfere with AV conduction. When present at a high burden, this type of AV block can be highly symptomatic. Catheter ablation techniques can be used to alleviate this type of AV block and restore normal AV conduction. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  9. Ablation article and method

    NASA Technical Reports Server (NTRS)

    Erickson, W. D.; Sullivan, E. M. (Inventor)

    1973-01-01

    An ablation article, such as a conical heat shield, having an ablating surface is provided with at least one discrete area of at least one seed material, such as aluminum. When subjected to ablation conditions, the seed material is ablated. Radiation emanating from the ablated seed material is detected to analyze ablation effects without disturbing the ablation surface. By providing different seed materials having different radiation characteristics, the ablating effects on various areas of the ablating surface can be analyzed under any prevailing ablation conditions. The ablating article can be provided with means for detecting the radiation characteristics of the ablated seed material to provide a self-contained analysis unit.

  10. Skin pre-ablation and laser assisted microjet injection for deep tissue penetration.

    PubMed

    Jang, Hun-Jae; Yeo, Seonggu; Yoh, Jack J

    2017-04-01

    For conventional needless injection, there still remain many unresolved issues such as the potential for cross-contamination, poor reliability of targeted delivery dose, and significantly painstaking procedures. As an alternative, the use of microjets generated with Er:YAG laser for delivering small doses with controlled penetration depths has been reported. In this study, a new system with two stages is evaluated for effective transdermal drug delivery. First, the skin is pre-ablated to eliminate the hard outer layer and second, laser-driven microjet penetrates the relatively weaker and freshly exposed epidermis. Each stage of operation shares a single Er:YAG laser that is suitable for skin ablation as well as for the generation of a microjet. In this study, pig skin is selected for quantification of the injection depth based on the two-stage procedure, namely pre-ablation and microjet injection. The three types of pre-ablation devised here consists of bulk ablation, fractional ablation, and fractional-rotational ablation. The number of laser pulses are 12, 18, and 24 for each ablation type. For fractional-rotational ablation, the fractional beams are rotated by 11.25° at each pulse. The drug permeation in the skin is evaluated using tissue marking dyes. The depth of penetration is quantified by a cross sectional view of the single spot injections. Multi-spot injections are also carried out to control the dose and spread of the drug. The benefits of a pre-ablation procedure prior to the actual microjet injection to the penetration is verified. The four possible combinations of injection are (a) microjet only; (b) bulk ablation and microjet injection; (c) fractional ablation and microjet injection; and (d) fractional-rotational ablation and microjet injection. Accordingly, the total depth increases with injection time for all cases. In particular, the total depth of penetration attained via fractional pre-ablation increased by 8 ∼ 11% and that of fractional

  11. Influence of the Liquid on Femtosecond Laser Ablation of Iron

    NASA Astrophysics Data System (ADS)

    Kanitz, A.; Hoppius, J. S.; Gurevich, E. L.; Ostendorf, A.

    Ultrashort pulse laser ablation has become a very important industrial method for highly precise material removal ranging from sensitive thin film processing to drilling and cutting of metals. Over the last decade, a new method to produce pure nanoparticles emerged from this technique: Pulsed Laser Ablation in Liquids (PLAL). By this method, the ablation of material by a laser beam is used to generate a metal vapor within the liquid in order to obtain nanoparticles from its recondensation process. It is well known that the liquid significantly alters the ablation properties of the substrate, in our case iron. For example, the ablation rate and crater morphology differ depending on the used liquid. We present our studies on the efficiency and quality of ablated grooves in water, methanol, acetone, ethanol and toluene. The produced grooves are investigated by means of white-light interferometry, EDX and SEM.

  12. Microwave ablation of hepatocellular carcinoma

    PubMed Central

    Poggi, Guido; Tosoratti, Nevio; Montagna, Benedetta; Picchi, Chiara

    2015-01-01

    Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s’, RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s’, showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA. PMID:26557950

  13. Overview of the CHarring Ablator Response (CHAR) Code

    NASA Technical Reports Server (NTRS)

    Amar, Adam J.; Oliver, A. Brandon; Kirk, Benjamin S.; Salazar, Giovanni; Droba, Justin

    2016-01-01

    An overview of the capabilities of the CHarring Ablator Response (CHAR) code is presented. CHAR is a one-, two-, and three-dimensional unstructured continuous Galerkin finite-element heat conduction and ablation solver with both direct and inverse modes. Additionally, CHAR includes a coupled linear thermoelastic solver for determination of internal stresses induced from the temperature field and surface loading. Background on the development process, governing equations, material models, discretization techniques, and numerical methods is provided. Special focus is put on the available boundary conditions including thermochemical ablation and contact interfaces, and example simulations are included. Finally, a discussion of ongoing development efforts is presented.

  14. Overview of the CHarring Ablator Response (CHAR) Code

    NASA Technical Reports Server (NTRS)

    Amar, Adam J.; Oliver, A. Brandon; Kirk, Benjamin S.; Salazar, Giovanni; Droba, Justin

    2016-01-01

    An overview of the capabilities of the CHarring Ablator Response (CHAR) code is presented. CHAR is a one-, two-, and three-dimensional unstructured continuous Galerkin finite-element heat conduction and ablation solver with both direct and inverse modes. Additionally, CHAR includes a coupled linear thermoelastic solver for determination of internal stresses induced from the temperature field and surface loading. Background on the development process, governing equations, material models, discretization techniques, and numerical methods is provided. Special focus is put on the available boundary conditions including thermochemical ablation, surface-to-surface radiation exchange, and flowfield coupling. Finally, a discussion of ongoing development efforts is presented.

  15. Laser Ablation for Cancer: Past, Present and Future

    PubMed Central

    Schena, Emiliano; Saccomandi, Paola; Fong, Yuman

    2017-01-01

    Laser ablation (LA) is gaining acceptance for the treatment of tumors as an alternative to surgical resection. This paper reviews the use of lasers for ablative and surgical applications. Also reviewed are solutions aimed at improving LA outcomes: hyperthermal treatment planning tools and thermometric techniques during LA, used to guide the surgeon in the choice and adjustment of the optimal laser settings, and the potential use of nanoparticles to allow biologic selectivity of ablative treatments. Promising technical solutions and a better knowledge of laser-tissue interaction should allow LA to be used in a safe and effective manner as a cancer treatment. PMID:28613248

  16. Molybdenum oxide nanocolloids prepared by an external field-assisted laser ablation in water

    NASA Astrophysics Data System (ADS)

    Spadaro, Salvatore; Bonsignore, Martina; Fazio, Enza; Cimino, Francesco; Speciale, Antonio; Trombetta, Domenico; Barreca, Francesco; Saija, Antonina; Neri, Fortunato

    2018-01-01

    he synthesis of extremely stable molybdenum oxide nanocolloids by pulsed laser ablation was studied. This green technique ensures the formation of contaminant-free nanostructures and the absence of by-products. A focused picosecond pulsed laser beam was used to ablate a solid molybdenum target immersed in deionized water. Molybdenum oxide nearly spherical nanoparticles with dimensions within few nanometers (20-100 nm) are synthesized when the ablation processes were carried out, in water, at room temperature and 80°C. The application of an external electric field during the ablation process induces a nanostructures reorganization, as indicated by Scanning-Transmission Electron Microscopy images analysis. The ablation products were also characterized by some spectroscopic techniques: conventional UV-vis optical absorption, atomic absorption, dynamic light scattering, micro-Raman and X-ray photoelectron spectroscopies. Finally, NIH/3T3 mouse fibroblasts were used to evaluate cell viability by the sulforhodamine B assay

  17. Microwave Ablation: Comparison of Simultaneous and Sequential Activation of Multiple Antennas in Liver Model Systems

    PubMed Central

    Harari, Colin M.; Magagna, Michelle; Bedoya, Mariajose; Lee, Fred T.; Lubner, Meghan G.; Hinshaw, J. Louis; Ziemlewicz, Timothy

    2016-01-01

    Purpose To compare microwave ablation zones created by using sequential or simultaneous power delivery in ex vivo and in vivo liver tissue. Materials and Methods All procedures were approved by the institutional animal care and use committee. Microwave ablations were performed in both ex vivo and in vivo liver models with a 2.45-GHz system capable of powering up to three antennas simultaneously. Two- and three-antenna arrays were evaluated in each model. Sequential and simultaneous ablations were created by delivering power (50 W ex vivo, 65 W in vivo) for 5 minutes per antenna (10 and 15 minutes total ablation time for sequential ablations, 5 minutes for simultaneous ablations). Thirty-two ablations were performed in ex vivo bovine livers (eight per group) and 28 in the livers of eight swine in vivo (seven per group). Ablation zone size and circularity metrics were determined from ablations excised postmortem. Mixed effects modeling was used to evaluate the influence of power delivery, number of antennas, and tissue type. Results On average, ablations created by using the simultaneous power delivery technique were larger than those with the sequential technique (P < .05). Simultaneous ablations were also more circular than sequential ablations (P = .0001). Larger and more circular ablations were achieved with three antennas compared with two antennas (P < .05). Ablations were generally smaller in vivo compared with ex vivo. Conclusion The use of multiple antennas and simultaneous power delivery creates larger, more confluent ablations with greater temperatures than those created with sequential power delivery. © RSNA, 2015 PMID:26133361

  18. Microwave Ablation: Comparison of Simultaneous and Sequential Activation of Multiple Antennas in Liver Model Systems.

    PubMed

    Harari, Colin M; Magagna, Michelle; Bedoya, Mariajose; Lee, Fred T; Lubner, Meghan G; Hinshaw, J Louis; Ziemlewicz, Timothy; Brace, Christopher L

    2016-01-01

    To compare microwave ablation zones created by using sequential or simultaneous power delivery in ex vivo and in vivo liver tissue. All procedures were approved by the institutional animal care and use committee. Microwave ablations were performed in both ex vivo and in vivo liver models with a 2.45-GHz system capable of powering up to three antennas simultaneously. Two- and three-antenna arrays were evaluated in each model. Sequential and simultaneous ablations were created by delivering power (50 W ex vivo, 65 W in vivo) for 5 minutes per antenna (10 and 15 minutes total ablation time for sequential ablations, 5 minutes for simultaneous ablations). Thirty-two ablations were performed in ex vivo bovine livers (eight per group) and 28 in the livers of eight swine in vivo (seven per group). Ablation zone size and circularity metrics were determined from ablations excised postmortem. Mixed effects modeling was used to evaluate the influence of power delivery, number of antennas, and tissue type. On average, ablations created by using the simultaneous power delivery technique were larger than those with the sequential technique (P < .05). Simultaneous ablations were also more circular than sequential ablations (P = .0001). Larger and more circular ablations were achieved with three antennas compared with two antennas (P < .05). Ablations were generally smaller in vivo compared with ex vivo. The use of multiple antennas and simultaneous power delivery creates larger, more confluent ablations with greater temperatures than those created with sequential power delivery. © RSNA, 2015.

  19. Precise ablation of dental hard tissues with ultra-short pulsed lasers. Preliminary exploratory investigation on adequate laser parameters.

    PubMed

    Bello-Silva, Marina Stella; Wehner, Martin; Eduardo, Carlos de Paula; Lampert, Friedrich; Poprawe, Reinhart; Hermans, Martin; Esteves-Oliveira, Marcella

    2013-01-01

    This study aimed to evaluate the possibility of introducing ultra-short pulsed lasers (USPL) in restorative dentistry by maintaining the well-known benefits of lasers for caries removal, but also overcoming disadvantages, such as thermal damage of irradiated substrate. USPL ablation of dental hard tissues was investigated in two phases. Phase 1--different wavelengths (355, 532, 1,045, and 1,064 nm), pulse durations (picoseconds and femtoseconds) and irradiation parameters (scanning speed, output power, and pulse repetition rate) were assessed for enamel and dentin. Ablation rate was determined, and the temperature increase measured in real time. Phase 2--the most favorable laser parameters were evaluated to correlate temperature increase to ablation rate and ablation efficiency. The influence of cooling methods (air, air-water spray) on ablation process was further analyzed. All parameters tested provided precise and selective tissue ablation. For all lasers, faster scanning speeds resulted in better interaction and reduced temperature increase. The most adequate results were observed for the 1064-nm ps-laser and the 1045-nm fs-laser. Forced cooling caused moderate changes in temperature increase, but reduced ablation, being considered unnecessary during irradiation with USPL. For dentin, the correlation between temperature increase and ablation efficiency was satisfactory for both pulse durations, while for enamel, the best correlation was observed for fs-laser, independently of the power used. USPL may be suitable for cavity preparation in dentin and enamel, since effective ablation and low temperature increase were observed. If adequate laser parameters are selected, this technique seems to be promising for promoting the laser-assisted, minimally invasive approach.

  20. Study of low-cost fabrication of ablative heat shields

    NASA Technical Reports Server (NTRS)

    Norwood, L. B.

    1972-01-01

    The major objectives were accomplished in three tasks: (1) modification of the ablative material composition for ease of fabrication as well as thermal and mechanical performance; (2) scaled-up, simplified, manufacturing techniques which resulted in cost reductions; and (3) the identification of a significant design problem caused by the differential pressure buildup imposed on mechanically attached ablative heat shield panels during launch.

  1. Bipolar radiofrequency ablation of liver metastases during laparotomy. First clinical experiences with a new multipolar ablation concept.

    PubMed

    Ritz, Joerg-Peter; Lehmann, Kai S; Reissfelder, Christoph; Albrecht, Thomas; Frericks, Bernd; Zurbuchen, Urte; Buhr, Heinz J

    2006-01-01

    Radiofrequency ablation (RFA) is a promising method for local treatment of liver malignancies. Currently available systems for radiofrequency ablation use monopolar current, which carries the risk of uncontrolled electrical current paths, collateral damages and limited effectiveness. To overcome this problem, we used a newly developed internally cooled bipolar application system in patients with irresectable liver metastases undergoing laparotomy. The aim of this study was to clinically evaluate the safety, feasibility and effectiveness of this new system with a novel multipolar application concept. Patients with a maximum of five liver metastases having a maximum diameter of 5 cm underwent laparotomy and abdominal exploration to control resectability. In cases of irresectability, RFA with the newly developed bipolar application system was performed. Treatment was carried out under ultrasound guidance. Depending on tumour size, shape and location, up to three applicators were simultaneously inserted in or closely around the tumour, never exceeding a maximum probe distance of 3 cm. In the multipolar ablation concept, the current runs alternating between all possible pairs of consecutively activated electrodes with up to 15 possible electrode combinations. Post-operative follow-up was evaluated by CT or MRI controls 24-48 h after RFA and every 3 months. In a total of six patients (four male, two female; 61-68 years), ten metastases (1.0-5.5 cm) were treated with a total of 14 RF applications. In four metastases three probes were used, and in another four and two metastases, two and one probes were used, respectively. During a mean ablation time of 18.8 min (10-31), a mean energy of 48.8 kJ (12-116) for each metastases was applied. No procedure-related complications occurred. The patients were released from the hospital between 7 and 12 days post-intervention (median 9 days). The post-interventional control showed complete tumour ablation in all cases. Bipolar

  2. Recent Advances in Tumor Ablation for Hepatocellular Carcinoma

    PubMed Central

    Kang, Tae Wook; Rhim, Hyunchul

    2015-01-01

    Image-guided tumor ablation for early stage hepatocellular carcinoma (HCC) is an accepted non-surgical treatment that provides excellent local tumor control and favorable survival benefit. This review summarizes the recent advances in tumor ablation for HCC. Diagnostic imaging and molecular biology of HCC has recently undergone marked improvements. Second-generation ultrasonography (US) contrast agents, new computed tomography (CT) techniques, and liver-specific contrast agents for magnetic resonance imaging (MRI) have enabled the early detection of smaller and inconspicuous HCC lesions. Various imaging-guidance tools that incorporate imaging-fusion between real-time US and CT/MRI, that are now common for percutaneous tumor ablation, have increased operator confidence in the accurate targeting of technically difficult tumors. In addition to radiofrequency ablation (RFA), various therapeutic modalities including microwave ablation, irreversible electroporation, and high-intensity focused ultrasound ablation have attracted attention as alternative energy sources for effective locoregional treatment of HCC. In addition, combined treatment with RFA and chemoembolization or molecular agents may be able to overcome the limitation of advanced or large tumors. Finally, understanding of the biological mechanisms and advances in therapy associated with tumor ablation will be important for successful tumor control. All these advances in tumor ablation for HCC will result in significant improvement in the prognosis of HCC patients. In this review, we primarily focus on recent advances in molecular tumor biology, diagnosis, imaging-guidance tools, and therapeutic modalities, and refer to the current status and future perspectives for tumor ablation for HCC. PMID:26674766

  3. Automated planning of ablation targets in atrial fibrillation treatment

    NASA Astrophysics Data System (ADS)

    Keustermans, Johannes; De Buck, Stijn; Heidbüchel, Hein; Suetens, Paul

    2011-03-01

    Catheter based radio-frequency ablation is used as an invasive treatment of atrial fibrillation. This procedure is often guided by the use of 3D anatomical models obtained from CT, MRI or rotational angiography. During the intervention the operator accurately guides the catheter to prespecified target ablation lines. The planning stage, however, can be time consuming and operator dependent which is suboptimal both from a cost and health perspective. Therefore, we present a novel statistical model-based algorithm for locating ablation targets from 3D rotational angiography images. Based on a training data set of 20 patients, consisting of 3D rotational angiography images with 30 manually indicated ablation points, a statistical local appearance and shape model is built. The local appearance model is based on local image descriptors to capture the intensity patterns around each ablation point. The local shape model is constructed by embedding the ablation points in an undirected graph and imposing that each ablation point only interacts with its neighbors. Identifying the ablation points on a new 3D rotational angiography image is performed by proposing a set of possible candidate locations for each ablation point, as such, converting the problem into a labeling problem. The algorithm is validated using a leave-one-out-approach on the training data set, by computing the distance between the ablation lines obtained by the algorithm and the manually identified ablation points. The distance error is equal to 3.8+/-2.9 mm. As ablation lesion size is around 5-7 mm, automated planning of ablation targets by the presented approach is sufficiently accurate.

  4. Guidance of aortic ablation using optical coherence tomography.

    PubMed

    Patel, Nirlep A; Li, Xingde; Stamper, Debra L; Fujimoto, James G; Brezinski, Mark E

    2003-04-01

    There is a significant need for an imaging modality that is capable of providing guidance for intravascular procedures, as current technologies suffer from significant limitations. In particular, laser ablation of in-stent restenosis, revascularization of chronic total occlusions, and pulmonary vein ablation could benefit from guidance. Optical coherence tomography (OCT), a recently introduced technology, is similar to ultrasound except that it measures the back-reflection of infrared light instead of sound. This study examines the ability of OCT to guide vascular laser ablation. Aorta samples underwent laser ablation using an argon laser at varying power outputs and were monitored with OCT collecting images at 4 frames. Samples were compared to the corresponding histopathology. Arterial layers could be differentiated in the images sequences. This allowed correlation of changes in the OCT image with power and duration in addition to histopathology. OCT provides real-time guidance of arterial ablation. At 4 frames, OCT was successfully able to show the microstructural changes in the vessel wall during laser ablation. Since current ablation procedures often injure surrounding tissue, the ability to minimize collateral damage to the adjoining tissue represents a useful advantage of this system. This study suggests a possible role for OCT in the guidance of intravascular procedures.

  5. Mucosal ablation in Barrett's esophagus.

    PubMed

    Walker, S J; Selvasekar, C R; Birbeck, N

    2002-01-01

    Barrett's esophagus is a prevalent, premalignant condition affecting the gastroesophageal junction and distal esophagus. Ablation plus antireflux therapy has recently been advocated to prevent the development of adenocarcinoma or to treat those unfit or unwilling to undergo esophagectomy. The present article, based on a search of Medline/ISI databases and cross-referencing of relevant articles, reviews the literature on this subject. A number of techniques have been used to remove the affected mucosa, including laser, electrocoagulation, argon plasma coagulation and photodynamic therapy but, as yet, none has been shown to be superior. Depending on the method used, ablation results in complete removal of Barrett's esophagus in approximately one third of patients and a partial response in nearly two-thirds. The resultant squamous mucosa is apparently 'normal' but may regress. To promote and maintain regeneration, antireflux therapy must be sufficient to reduce repetitive injury to the esophageal mucosa. Whether ablation reduces the cancer risk or delays its occurrence is unknown, though recent data suggests benefit. Complications are infrequent and usually mild. Regular follow-up endoscopy and deep biopsies continue to be necessary. Careful data from much larger populations with long-term follow-up is required before ablation reaches the stage of broad clinical application.

  6. Toward single-cell analysis by plume collimation in laser ablation electrospray ionization mass spectrometry.

    PubMed

    Stolee, Jessica A; Vertes, Akos

    2013-04-02

    Ambient ionization methods for mass spectrometry have enabled the in situ and in vivo analysis of biological tissues and cells. When an etched optical fiber is used to deliver laser energy to a sample in laser ablation electrospray ionization (LAESI) mass spectrometry, the analysis of large single cells becomes possible. However, because in this arrangement the ablation plume expands in three dimensions, only a small portion of it is ionized by the electrospray. Here we show that sample ablation within a capillary helps to confine the radial expansion of the plume. Plume collimation, due to the altered expansion dynamics, leads to greater interaction with the electrospray plume resulting in increased ionization efficiency, reduced limit of detection (by a factor of ~13, reaching 600 amol for verapamil), and extended dynamic range (6 orders of magnitude) compared to conventional LAESI. This enhanced sensitivity enables the analysis of a range of metabolites from small cell populations and single cells in the ambient environment. This technique has the potential to be integrated with flow cytometry for high-throughput metabolite analysis of sorted cells.

  7. Bimodal electric tissue ablation (BETA) - in-vivo evaluation of the effect of applying direct current before and during radiofrequency ablation of porcine liver.

    PubMed

    Cockburn, J F; Maddern, G J; Wemyss-Holden, S A

    2007-03-01

    To examine the effect of applying increasing amounts of direct current (DC) before and during alternating current radiofrequency ablation of porcine liver. Using a Radiotherapeutics RF3000 generator, a 9 V AC/DC transformer and a 16 G plain aluminium tube as an electrode, a control group of 24 porcine hepatic radiofrequency ablation zones was compared with 24 zones created using a bimodal electric tissue ablation (BETA) technique in three pigs. All ablations were terminated when tissue impedance rose to greater than 999 Omega or radiofrequency energy input fell below 5 W on three successive measurements taken at 1 min intervals. BETA ablations were performed in two phases: an initial phase of variable duration DC followed by a second phase during which standard radiofrequency ablation was applied simultaneously with DC. During this second phase, radiofrequency power input was regulated by the feedback circuitry of the RF3000 generator according to changes in tissue impedance. The diameters (mm) of each ablation zone were measured by two observers in two planes perpendicular to the plane of needle insertion. The mean short axis diameter of each ablation zone was subjected to statistical analysis. With increased duration of prior application of DC, there was a progressive increase in the diameter of the ablation zone (p<0.001). This effect increased sharply up to 300 s of pre-treatment after which a further increase in diameter occurred, but at a much lesser rate. A maximum ablation zone diameter of 32 mm was produced (control diameters 10-13 mm). Applying a 9 V DC to porcine liver in vivo, and continuing this DC application during subsequent radiofrequency ablation, results in larger ablation zone diameters compared with radiofrequency ablation alone.

  8. Experimental investigation of the dynamics of pellet ablation on the Texas Experimental Tokamak

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Durst, R.D.

    1988-01-01

    Rapid fluctuations in the ablation of hydrogen pellets in the Texas Experimental Tokamak were studied using fast photographic techniques. It is proposed that the fluctuations are a type of relaxation oscillation driven by the motion of the particle across the magnetic field. This is shown to be consistent with a time-dependent model of plasma shielding due to Kaufmann et al. A technique to include this effect in calculations of pellet ablation is discussed. Spatially resolved measurements of the temperature and density in the pellet-ablation cloud were obtained by line-to-continuum ratios and Stark broadening, respectively. Typical parameters in the pellet-ablation cloudmore » are 5-6 eV and 1.0-1.5 {times} 10{sup 17} cm{sup {minus}3}. The flow along the magnetic field is found to be isobaric. The heating of the expanding ablatant is strongly asymmetric, being stronger on the side facing the electron-drift direction. This may be due to suprathermal electrons.« less

  9. Endometrial ablation in the management of abnormal uterine bleeding.

    PubMed

    Laberge, Philippe; Leyland, Nicholas; Murji, Ally; Fortin, Claude; Martyn, Paul; Vilos, George; Leyland, Nicholas; Wolfman, Wendy; Allaire, Catherine; Awadalla, Alaa; Dunn, Sheila; Heywood, Mark; Lemyre, Madeleine; Marcoux, Violaine; Potestio, Frank; Rittenberg, David; Singh, Sukhbir; Yeung, Grace

    2015-04-01

    Abnormal uterine bleeding (AUB) is the direct cause of a significant health care burden for women, their families, and society as a whole. Up to 30% of women will seek medical assistance for the problem during their reproductive years. To provide current evidence-based guidelines on the techniques and technologies used in endometrial ablation (EA), a minimally invasive technique for the management of AUB of benign origin. Members of the guideline committee were selected on the basis of individual expertise to represent a range of practical and academic experience in terms of both location in Canada and type of practice, as well as subspecialty expertise and general background in gynaecology. The committee reviewed all available evidence in the English medical literature, including published guidelines, and evaluated surgical and patient outcomes for the various EA techniques. Recommendations were established by consensus. Published literature was retrieved through searches of MEDLINE and The Cochrane Library in 2013 and 2014 using appropriate controlled vocabulary and key words (endometrial ablation, hysteroscopy, menorrhagia, heavy menstrual bleeding, AUB, hysterectomy). RESULTS were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies written in English from January 2000 to November 2014. Searches were updated on a regular basis and incorporated in the guideline to December 2014. Grey (unpublished) literature was identifies through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1). This document reviews the evidence regarding the available techniques and technologies for EA

  10. Fetoscopic laser ablation of placental anastomoses in twin-twin transfusion syndrome using 'Solomon technique'.

    PubMed

    Ruano, R; Rodo, C; Peiro, J L; Shamshirsaz, A A; Haeri, S; Nomura, M L; Salustiano, E M A; de Andrade, K K; Sangi-Haghpeykar, H; Carreras, E; Belfort, M A

    2013-10-01

    To document perinatal outcomes following use of the 'Solomon technique' in the selective photocoagulation of placental anastomoses for severe twin-twin transfusion syndrome (TTTS). Between January 2010 and July 2012, data were collected from 102 consecutive monochorionic twin pregnancies complicated by severe TTTS that underwent fetoscopic laser ablation at four different centers. We compared outcomes between subjects that underwent selective laser coagulation using the Solomon technique (cases) and those that underwent selective laser coagulation without this procedure (controls). Of the 102 pregnancies examined, 26 (25.5%) underwent the Solomon technique and 76 (74.5%) did not. Of the 204 fetuses, 139 (68.1%) survived up to 30 days of age. At least one twin survived in 82 (80.4%) pregnancies and both twins survived in 57 (55.9%) pregnancies. When compared with the control group, the Solomon-technique group had a significantly higher survival rate for both twins (84.6 vs 46.1%; P < 0.01) and a higher overall neonatal survival rate (45/52 (86.5%) vs 94/152 (61.8%); P < 0.01). Use of the Solomon technique remained independently associated with dual twin survival (adjusted odds ratio (aOR), 11.35 (95% CI, 3.11-53.14); P = 0.0007) and overall neonatal survival rate (aOR, 4.65 (95% CI, 1.59-13.62); P = 0.005) on multivariable analysis. There were no cases of recurrent TTTS or twin anemia-polycythemia sequence (TAPS) in the Solomon-technique group. Use of the Solomon technique following selective laser coagulation of placental anastomoses appears to improve twin survival and may reduce the risk of recurrent TTTS and TAPS. Our data support the idea of performing a randomized controlled trial to evaluate the effectiveness of the Solomon technique. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.

  11. Development of Naphthalene PLIF for Making Quantitative Measurements of Ablation Products Transport in Supersonic Flows

    NASA Astrophysics Data System (ADS)

    Combs, Christopher; Clemens, Noel

    2014-11-01

    Ablation is a multi-physics process involving heat and mass transfer and codes aiming to predict ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. Low-temperature sublimating ablators such as naphthalene can be used to create a limited physics problem and simulate ablation at relatively low temperature conditions. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of naphthalene to visualize the transport of ablation products in a supersonic flow. In the current work, naphthalene PLIF will be used to make quantitative measurements of the concentration of ablation products in a Mach 5 turbulent boundary layer. For this technique to be used for quantitative research in supersonic wind tunnel facilities, the fluorescence properties of naphthalene must first be investigated over a wide range of state conditions and excitation wavelengths. The resulting calibration of naphthalene fluorescence will be applied to the PLIF images of ablation from a boundary layer plug, yielding 2-D fields of naphthalene mole fraction. These images may help provide data necessary to validate computational models of ablative thermal protection systems for reentry vehicles. Work supported by NASA Space Technology Research Fellowship Program under grant NNX11AN55H.

  12. Nonequilibrium Ablation of Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih K.; Gokcen, Tahir

    2012-01-01

    In previous work, an equilibrium ablation and thermal response model for Phenolic Impregnated Carbon Ablator was developed. In general, over a wide range of test conditions, model predictions compared well with arcjet data for surface recession, surface temperature, in-depth temperature at multiple thermocouples, and char depth. In this work, additional arcjet tests were conducted at stagnation conditions down to 40 W/sq cm and 1.6 kPa. The new data suggest that nonequilibrium effects become important for ablation predictions at heat flux or pressure below about 80 W/sq cm or 10 kPa, respectively. Modifications to the ablation model to account for nonequilibrium effects are investigated. Predictions of the equilibrium and nonequilibrium models are compared with the arcjet data.

  13. Advances in local ablation of malignant liver lesions

    PubMed Central

    Eisele, Robert M

    2016-01-01

    Local ablation of liver tumors matured during the recent years and is now proven to be an effective tool in the treatment of malignant liver lesions. Advances focus on the improvement of local tumor control by technical innovations, individual selection of imaging modalities, more accurate needle placement and the free choice of access to the liver. Considering data found in the current literature for conventional local ablative treatment strategies, virtually no single technology is able to demonstrate an unequivocal superiority. Hints at better performance of microwave compared to radiofrequency ablation regarding local tumor control, duration of the procedure and potentially achievable larger size of ablation areas favour the comparably more recent treatment modality; image fusion enables more patients to undergo ultrasound guided local ablation; magnetic resonance guidance may improve primary success rates in selected patients; navigation and robotics accelerate the needle placement and reduces deviation of needle positions; laparoscopic thermoablation results in larger ablation areas and therefore hypothetically better local tumor control under acceptable complication rates, but seems to be limited to patients with no, mild or moderate adhesions following earlier surgical procedures. Apart from that, most techniques appear technically feasible, albeit demanding. Which technology will in the long run become accepted, is subject to future work. PMID:27099433

  14. CuInGaSe{sub 2} nanoparticles by pulsed laser ablation in liquid medium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mendivil, M.I.; García, L.V.; Krishnan, B.

    2015-12-15

    Highlights: • CIGS nanocolloids were synthesized using PLAL technique. • Characterized their morphology, structure, composition and optical properties. • Morphologies were dependent on ablation wavelength and liquid medium. • Optical absorption and bandgap of these nanocolloids were tunable. - Abstract: Pulsed laser ablation in liquid medium (PLALM) is a nanofabrication technique to produce complex nanostructures. CuInGaSe{sub 2} (CIGS) is an alloy with applications in photovoltaic industry. In this work, we studied the effects of laser ablation wavelength, energy fluence and liquid medium on the properties of the CIGS nanoparticles synthesized by PLALM. The nanoparticles obtained were analyzed by transmission electronmore » microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy. XPS results confirmed the chemical states and composition of the ablated products. TEM analysis showed different morphologies for the nanomaterials obtained in different liquid media and ablation wavelengths. The optical properties for these CIGS nanocolloids were analyzed using UV–vis absorption spectroscopy. The results demonstrated the use of PLALM as a useful synthesis technique for nanoparticles of quaternary photovoltaic materials.« less

  15. Ablative Thermal Response Analysis Using the Finite Element Method

    NASA Technical Reports Server (NTRS)

    Dec John A.; Braun, Robert D.

    2009-01-01

    A review of the classic techniques used to solve ablative thermal response problems is presented. The advantages and disadvantages of both the finite element and finite difference methods are described. As a first step in developing a three dimensional finite element based ablative thermal response capability, a one dimensional computer tool has been developed. The finite element method is used to discretize the governing differential equations and Galerkin's method of weighted residuals is used to derive the element equations. A code to code comparison between the current 1-D tool and the 1-D Fully Implicit Ablation and Thermal Response Program (FIAT) has been performed.

  16. Efficacy of microwave ablation versus radiofrequency ablation for the treatment of hepatocellular carcinoma in patients with chronic liver disease: a randomised controlled phase 2 trial.

    PubMed

    Vietti Violi, Naïk; Duran, Rafael; Guiu, Boris; Cercueil, Jean-Pierre; Aubé, Christophe; Digklia, Antonia; Pache, Isabelle; Deltenre, Pierre; Knebel, Jean-François; Denys, Alban

    2018-05-01

    Radiofrequency ablation is the recommended treatment for patients with hepatocellular carcinoma who have lesions smaller than 3 cm and are therefore not candidates for surgery. Microwave ablation is a more recent technique with certain theoretical advantages that have not yet been confirmed clinically. We aimed to compare the efficacy of both techniques in the treatment of hepatocellular carcinoma lesions of 4 cm or smaller. We did a randomised controlled, single-blinded phase 2 trial at four tertiary university centres in France and Switzerland. Patients with chronic liver disease and hepatocellular carcinoma with up to three lesions of 4 cm or smaller who were not eligible for surgery were randomised to receive microwave ablation (experimental group) or radiofrequency ablation (control group). Randomisation was centralised and done by use of a fixed block method (block size 4). Patients were randomly assigned by a co-investigator by use of the sealed opaque envelope method and were masked to the treatment; physicians were not masked to treatment, since the devices used were different. The primary outcome was the proportion of lesions with local tumour progression at 2 years of follow-up. Local tumour progression was defined as the appearance of a new nodule with features typical of hepatocellular carcinoma in the edge of the ablation zone. All analyses were done in the per-protocol population. The study is completed, but patients will continue to be followed up for 5 years. This study is registered with ClinicalTrials.gov, number NCT02859753. Between Nov 15, 2011, and Feb 27, 2015, 152 patients were randomly assigned: 76 patients to receive microwave ablation and 76 patients to receive radiofrequency ablation. For the per-protocol analysis, five patients were excluded from the microwave ablation group as were three patients from the radiofrequency ablation group. Median follow-up was 26 months (IQR 18-29) in the microwave ablation group and 25 months (18-34) in

  17. Efficacy and survival analysis of percutaneous radiofrequency versus microwave ablation for hepatocellular carcinoma: an Egyptian multidisciplinary clinic experience.

    PubMed

    Abdelaziz, Ashraf; Elbaz, Tamer; Shousha, Hend Ibrahim; Mahmoud, Sherif; Ibrahim, Mostafa; Abdelmaksoud, Ahmed; Nabeel, Mohamed

    2014-12-01

    Hepatocellular carcinoma (HCC) is a primary tumor of the liver with poor prognosis. For early stage HCC, treatment options include surgical resection, liver transplantation, and percutaneous ablation. Percutaneous ablative techniques (radiofrequency and microwave techniques) emerged as best therapeutic options for nonsurgical patients. We aimed to determine the safety and efficacy of radiofrequency and microwave procedures for ablation of early stage HCC lesions and prospectively follow up our patients for survival analysis. One Hundred and 11 patients with early HCC are managed in our multidisciplinary clinic using either radiofrequency or microwave ablation. Patients are assessed for efficacy and safety. Complete ablation rate, local recurrence, and overall survival analysis are compared between both procedures. Radiofrequency ablation group (n = 45) and microwave ablation group (n = 66) were nearly comparable as regards the tumor and patients characteristics. Complete ablation was achieved in 94.2 and 96.1% of patients managed by radiofrequency and microwave ablation techniques, respectively (p value 0.6) with a low rate of minor complications (11.1 and 3.2, respectively) including subcapsular hematoma, thigh burn, abdominal wall skin burn, and pleural effusion. Ablation rates did not differ between ablated lesions ≤ 3 and 3-5 cm. A lower incidence of local recurrence was observed in microwave group (3.9 vs. 13.5% in radiofrequency group, p value 0.04). No difference between both groups as regards de novo lesions, portal vein thrombosis, and abdominal lymphadenopathy. The overall actuarial probability of survival was 91.6% at 1 year and 86.1% at 2 years with a higher survival rates noticed in microwave group but still without significant difference (p value 0.49). Radiofrequency and microwave ablations led to safe and equivalent ablation and survival rates (with superiority for microwave ablation as regards the incidence of local recurrence).

  18. [INVITED] Control of femtosecond pulsed laser ablation and deposition by temporal pulse shaping

    NASA Astrophysics Data System (ADS)

    Garrelie, Florence; Bourquard, Florent; Loir, Anne--Sophie; Donnet, Christophe; Colombier, Jean-Philippe

    2016-04-01

    This study explores the effects of temporal laser pulse shaping on femtosecond pulsed laser deposition (PLD). The potential of laser pulses temporally tailored on ultrafast time scales is used to control the expansion and the excitation degree of ablation products including atomic species and nanoparticles. The ablation plume generated by temporally shaped femtosecond pulsed laser ablation of aluminum and graphite targets is studied by in situ optical diagnostic methods. Taking advantage of automated pulse shaping techniques, an adaptive procedure based on spectroscopic feedback regulates the irradiance for the enhancement of typical plasma features. Thin films elaborated by unshaped femtosecond laser pulses and by optimized sequence indicate that the nanoparticles generation efficiency is strongly influenced by the temporal shaping of the laser irradiation. The ablation processes leading either to the generation of the nanoparticles either to the formation of plasma can be favored by using a temporal shaping of the laser pulse. Insights are given on the possibility to control the quantity of the nanoparticles. The temporal laser pulse shaping is shown also to strongly modify the laser-induced plasma contents and kinetics for graphite ablation. Temporal pulse shaping proves its capability to reduce the number of slow radicals while increasing the proportion of monomers, with the addition of ionized species in front of the plume. This modification of the composition and kinetics of plumes in graphite ablation using temporal laser pulse shaping is discussed in terms of modification of the structural properties of deposited Diamond-Like Carbon films (DLC). This gives rise to a better understanding of the growth processes involved in femtosecond-PLD and picosecond-PLD of DLC suggesting the importance of neutral C atoms, which are responsible for the subplantation process.

  19. Preparation of antibacterial textile using laser ablation method

    NASA Astrophysics Data System (ADS)

    Shahidi, Sheila; Rashidian, M.; Dorranian, D.

    2018-02-01

    A facile in situ laser ablation synthesis of Copper nanoparticles on cotton fabric is reported in this paper. This synthetic method is a laser ablation based fabrication of Cu nanoparticles on cotton fabric for improved performance and antibacterial activity. The treated cotton fabric was characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, UV-Visible spectroscopic techniques and antibacterial counting test. Very good antibacterial behavior of treated fabrics achieved. This fabric can be used as medical and industrial textiles.

  20. State-of-the-art and emerging technologies for atrial fibrillation ablation.

    PubMed

    Dewire, Jane; Calkins, Hugh

    2010-03-01

    Catheter ablation is an important treatment modality for patients with atrial fibrillation (AF). Although the superiority of catheter ablation over antiarrhythmic drug therapy has been demonstrated in middle-aged patients with paroxysmal AF, the role the procedure in other patient subgroups-particularly those with long-standing persistent AF-has not been well defined. Furthermore, although AF ablation can be performed with reasonable efficacy and safety by experienced operators, long-term success rates for single procedures are suboptimal. Fortunately, extensive ongoing research will improve our understanding of the mechanisms of AF, and considerable funds are being invested in developing new ablation technologies to improve patient outcomes. These technologies include ablation catheters designed to electrically isolate the pulmonary veins with improved safety, efficacy, and speed, catheters designed to deliver radiofrequency energy with improved precision, robotic systems to address the technological demands of the procedure, improved imaging and electrical mapping systems, and MRI-guided ablation strategies. The tools, technologies, and techniques that will ultimately stand the test of time and become the standard approach to AF ablation in the future remain unclear. However, technological advances are sure to result in the necessary improvements in the safety and efficacy of AF ablation procedures.

  1. Visualization of Capsule Reentry Vehicle Heat Shield Ablation Using Naphthalene PLIF

    NASA Technical Reports Server (NTRS)

    Combs, Christopher S.; Clemens, Noel T.; Danehy, Paul M.

    2014-01-01

    The Orion Multi-Purpose Crew Vehicle (MPCV) will use an ablative heat shield and improved understanding of the ablation process would be beneficial for design purposes. Given that ablation is a multi-physics process involving heat and mass transfer, codes aiming to predict heat shield ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to visualize the transport of ablation products in a supersonic flow. Since ablation at reentry temperatures can be difficult to recreate in a laboratory setting it is desirable to create a limited physics problem and simulate the ablation process at relatively low temperature conditions using naphthalene. A scaled Orion MPCV model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel at various angles of attack in the current work. PLIF imaging reveals the distribution of the ablation products as they are transported into the heat-shield boundary layer and over the capsule shoulders into the separated shear layer and backshell recirculation region. Visualizations of the capsule shear layer using both naphthalene PLIF and Schlieren imaging compared favorably. High concentrations of naphthalene in the capsule separated flow region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure were observed using the naphthalene PLIF technique. The capsule shear layer was also shown to generally appear to be more turbulent at lower angles of attack. Furthermore, the PLIF signal increased steadily over the course of a run indicating that during a wind tunnel run the model heated up and the rate of naphthalene ablation increased. The shear layer showed increasing signs of turbulence over the course of a wind tunnel run

  2. Use of CT Hounsfield unit density to identify ablated tumor after laparoscopic radiofrequency ablation of hepatic tumors.

    PubMed

    Berber, E; Foroutani, A; Garland, A M; Rogers, S J; Engle, K L; Ryan, T L; Siperstein, A E

    2000-09-01

    When attempting to interpret CT scans after radiofrequency thermal ablation (RFA) of liver tumors, it is sometimes difficult to distinguish ablated from viable tumor tissue. Identification of the two types of tissue is specially problematic for lesions that are hypodense before ablation. The aim of this study was to determine whether quantitative Hounsfield unit (HU) density measurements can be used to document the lack of tumor perfusion and thereby identify ablated tissue. Liver spiral CT scans of 13 patients with 51 lesions undergoing laparoscopic RFA for metastatic liver tumors within a 2-year time period were reviewed. HU density of the lesions as well as normal liver were measured pre- and postoperatively in each CT phase (noncontrast, arterial, portovenous). Statistical analyses were performed using Student's paired t-test and ANOVA. Normal liver parenchyma, which was used as a control, showed a similar increase with contrast injection in both pre- and postprocedure CT scans (56.4 +/- 2.4 vs 57.1 +/- 2.4 HU, respectively; p = 0.3). In contrast, ablated liver lesions showed a preablation increase of 45.7 +/- 3.4 HU but only a minimal postablation increase of 6.6 +/- 0.7 HU (p < 0.0001). This was true for highly vascular tumors (neuroendocrine) as well as hypovascular ones (adenocarcinoma). This is the first study to define quantitative radiological criteria using HU density for the evaluation of ablated tissues. A lack of increase in HU density with contrast injection indicates necrotic tissue, whereas perfused tissue shows an increase in HU density. This technique can be used in the evaluation of patients undergoing RFA.

  3. Picosecond laser ablation of polyamide electrospun nanofibers

    NASA Astrophysics Data System (ADS)

    Götze, Marco; Krimig, Olaf; Kürbitz, Tobias; Henning, Sven; Heilmann, Andreas; Hillrichs, Georg

    2017-02-01

    Electrospun nanofibers mats have a great potential in tissue engineering and regenerative medicine. Their high porosity and enormous volume to surface ratio stimulate the growth and adhesion of mammalian cells and serve as a stable support structure. These suitable properties can be further optimized by structuring of the nanofibers. Ultrashort pulsed lasers can be used for modifying of the electrospun nanofibers without significant heat exposure. It seems also possible to generate very fine cuts from the fiber mats. In this study, polyamide electrospun nanofibers samples were processed with picosecond UV-laser irradiation (λ = 355 nm, τ = 15 ps). The samples were processed in dry, wet and immersed condition. To optimize cutting and structuring of nanofiber tissue flakes, the influence of different laser parameters on line widths, edge quality, heat-affected zone (HAZ) and the contamination of the fibers by ablated particles (debris) were examined. One additional aim was the minimization of the flake size. It was possible to generate nanofiber flakes in the sub-millimeter range. The quality of the nanofiber flakes could be improved by ablation near the ablation threshold of the material. For cutting under wet conditions shrinking of the flakes has to be taken into account.

  4. Remote magnetic navigation for mapping and ablating right ventricular outflow tract tachycardia.

    PubMed

    Thornton, Andrew S; Jordaens, Luc J

    2006-06-01

    Navigation, mapping, and ablation in the right ventricular outflow tract (RVOT) can be difficult. Catheter navigation using external magnetic fields may allow more accurate mapping and ablation. The purpose of this study was to assess the feasibility of RVOT tachycardia ablation using remote magnetic navigation. Mapping and ablation were performed in eight patients with outflow tract ventricular arrhythmias. Tachycardia mapping was undertaken with a 64-polar basket catheter, followed by remote activation and pace-mapping using a magnetically enabled catheter. The area of interest was localized on the basket catheter in seven patients in whom an RVOT arrhythmia was identified. Remote navigation of the magnetic catheter to this area was followed by pace-mapping. Ablation was performed at the site of perfect pace-mapping, with earliest activation if possible. Acute success was achieved in all patients (median four applications). Median procedural time was 144 minutes, with 13.4 minutes of patient fluoroscopy time and 3.8 minutes of physician fluoroscopy time. No complications occurred. One recurrence occurred during follow-up (mean 366 days). RVOT tachycardias can be mapped and ablated using remote magnetic navigation, initially guided by a basket catheter. Precise activation and pace-mapping are possible. Remote magnetic navigation permitted low fluoroscopy exposure for the physician. Long-term results are promising.

  5. Microwave ablation versus radiofrequency ablation in the kidney: high-power triaxial antennas create larger ablation zones than similarly sized internally cooled electrodes.

    PubMed

    Laeseke, Paul F; Lee, Fred T; Sampson, Lisa A; van der Weide, Daniel W; Brace, Christopher L

    2009-09-01

    To determine whether microwave ablation with high-power triaxial antennas creates significantly larger ablation zones than radiofrequency (RF) ablation with similarly sized internally cooled electrodes. Twenty-eight 12-minute ablations were performed in an in vivo porcine kidney model. RF ablations were performed with a 200-W pulsed generator and either a single 17-gauge cooled electrode (n = 9) or three switched electrodes spaced 1.5 cm apart (n = 7). Microwave ablations were performed with one (n = 7), two (n = 3), or three (n = 2) 17-gauge triaxial antennas to deliver 90 W continuous power per antenna. Multiple antennas were powered simultaneously. Temperatures 1 cm from the applicator were measured during two RF and microwave ablations each. Animals were euthanized after ablation and ablation zone diameter, cross-sectional area, and circularity were measured. Comparisons between groups were performed with use of a mixed-effects model with P values less than .05 indicating statistical significance. No adverse events occurred during the procedures. Three-electrode RF (mean area, 14.7 cm(2)) and single-antenna microwave (mean area, 10.9 cm(2)) ablation zones were significantly larger than single-electrode RF zones (mean area, 5.6 cm(2); P = .001 and P = .0355, respectively). No significant differences were detected between single-antenna microwave and multiple-electrode RF. Ablation zone circularity was similar across groups (P > .05). Tissue temperatures were higher during microwave ablation (maximum temperature of 123 degrees C vs 100 degrees C for RF). Microwave ablation with high-power triaxial antennas created larger ablation zones in normal porcine kidneys than RF ablation with similarly sized applicators.

  6. Microwave ablation in primary and secondary liver tumours: technical and clinical approaches.

    PubMed

    Meloni, Maria Franca; Chiang, Jason; Laeseke, Paul F; Dietrich, Christoph F; Sannino, Angela; Solbiati, Marco; Nocerino, Elisabetta; Brace, Christopher L; Lee, Fred T

    2017-02-01

    Thermal ablation is increasingly being utilised in the treatment of primary and metastatic liver tumours, both as curative therapy and as a bridge to transplantation. Recent advances in high-powered microwave ablation systems have allowed physicians to realise the theoretical heating advantages of microwave energy compared to other ablation modalities. As a result there is a growing body of literature detailing the effects of microwave energy on tissue heating, as well as its effect on clinical outcomes. This article will discuss the relevant physics, review current clinical outcomes and then describe the current techniques used to optimise patient care when using microwave ablation systems.

  7. Assessment of liver ablation using cone beam computed tomography.

    PubMed

    Abdel-Rehim, Mohamed; Ronot, Maxime; Sibert, Annie; Vilgrain, Valérie

    2015-01-14

    To investigate the feasibility and accuracy of cone beam computed tomography (CBCT) in assessing the ablation zone after liver tumor ablation. Twenty-three patients (17 men and 6 women, range: 45-85 years old, mean age 65 years) with malignant liver tumors underwent ultrasound-guided percutaneous tumor ablation [radiofrequency (n = 14), microwave (n = 9)] followed by intravenous contrast-enhanced CBCT. Baseline multidetector computed tomography (MDCT) and peri-procedural CBCT images were compared. CBCT image quality was assessed as poor, good, or excellent. Image fusion was performed to assess tumor coverage, and quality of fusion was rated as bad, good, or excellent. Ablation zone volumes on peri-procedural CBCT and post-procedural MDCT were compared using the non-parametric paired Wilcoxon t-test. Rate of primary ablation effectiveness was 100%. There were no complications related to ablation. Local tumor recurrence and new liver tumors were found 3 mo after initial treatment in one patient (4%). The ablation zone was identified in 21/23 (91.3%) patients on CBCT. The fusion of baseline MDCT and peri-procedural CBCT images was feasible in all patients and showed satisfactory tumor coverage (at least 5-mm margin). CBCT image quality was poor, good, and excellent in 2 (9%), 8 (35%), and 13 (56%), patients respectively. Registration quality between peri-procedural CBCT and post-procedural MDCT images was good to excellent in 17/23 (74%) patients. The median ablation volume on peri-procedural CBCT and post-procedural MDCT was 30 cm(3) (range: 4-95 cm(3)) and 30 cm(3) (range: 4-124 cm(3)), respectively (P-value > 0.2). There was a good correlation (r = 0.79) between the volumes of the two techniques. Contrast-enhanced CBCT after tumor ablation of the liver allows early assessment of the ablation zone.

  8. Microwave ablation at 10.0 GHz achieves comparable ablation zones to 1.9 GHz in ex vivo bovine liver.

    PubMed

    Luyen, Hung; Gao, Fuqiang; Hagness, Susan C; Behdad, Nader

    2014-06-01

    We demonstrate the feasibility of using high-frequency microwaves for tissue ablation by comparing the performance of a 10 GHz microwave ablation system with that of a 1.9 GHz system. Two sets of floating sleeve dipole antennas operating at these frequencies were designed and fabricated for use in ex vivo experiments with bovine livers. Combined electromagnetic and transient thermal simulations were conducted to analyze the performance of these antennas. Subsequently, a total of 16 ablation experiments (eight at 1.9 GHz and eight at 10.0 GHz) were conducted at a power level of 42 W for either 5 or 10 min. In all cases, the 1.9 and 10 GHz experiments resulted in comparable ablation zone dimensions. Temperature monitoring probes revealed faster heating rates in the immediate vicinity of the 10.0 GHz antenna compared to the 1.9 GHz antenna, along with a slightly delayed onset of heating farther from the 10 GHz antenna, suggesting that heat conduction plays a greater role at higher microwave frequencies in achieving a comparably sized ablation zone. The results obtained from these experiments agree very well with the combined electromagnetic/thermal simulation results. These simulations and experiments show that using lower frequency microwaves does not offer any significant advantages, in terms of the achievable ablation zones, over using higher frequency microwaves. Indeed, it is demonstrated that high-frequency microwave antennas may be used to create reasonably large ablation zones. Higher frequencies offer the advantage of smaller antenna size, which is expected to lead to less invasive interstitial devices and may possibly lead to the development of more compact multielement arrays with heating properties not available from single-element antennas.

  9. Radiofrequency ablation of hepatocellular carcinoma: Mono or multipolar?

    PubMed

    Cartier, Victoire; Boursier, Jérôme; Lebigot, Jérôme; Oberti, Frédéric; Fouchard-Hubert, Isabelle; Aubé, Christophe

    2016-03-01

    Thermo-ablation by radiofrequency is recognized as a curative treatment for early-stage hepatocellular carcinoma. However, local recurrence may occur because of incomplete peripheral tumor destruction. Multipolar radiofrequency has been developed to increase the size of the maximal ablation zone. We aimed to compare the efficacy of monopolar and multipolar radiofrequency for the treatment of hepatocellular carcinoma and determine factors predicting failure. A total of 171 consecutive patients with 214 hepatocellular carcinomas were retrospectively included. One hundred fifty-eight tumors were treated with an expandable monopolar electrode and 56 with a multipolar technique using several linear bipolar electrodes. Imaging studies at 6 weeks after treatment, then every 3 months, assessed local effectiveness. Radiofrequency failure was defined as persistent residual tumor after two sessions (primary radiofrequency failure) or local tumor recurrence during follow-up. This study received institutional review board approval (number 2014/77). Imaging showed complete tumor ablation in 207 of 214 lesions after the first session of radiofrequency. After a second session, only two cases of residual viable tumor were observed. During follow-up, there were 46 local tumor recurrences. Thus, radiofrequency failure occurred in 48/214 (22.4%) cases. By multivariate analysis, technique (P < 0.001) and tumor size (P = 0.023) were independent predictors of radiofrequency failure. Failure rate was lower with the multipolar technique for tumors < 25 mm (P = 0.023) and for tumors between 25 and 45 mm (P = 0.082). There was no difference for tumors ≥ 45 mm (P = 0.552). Compared to monopolar radiofrequency, multipolar radiofrequency improves tumor ablation with a subsequent lower rate of local tumor recurrence. © 2015 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

  10. Laser ablation mechanism of transparent layers on semiconductors with ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Rublack, Tino; Hartnauer, Stefan; Mergner, Michael; Muchow, Markus; Seifert, Gerhard

    2011-12-01

    Transparent dielectric layers on semiconductors are used as anti-reflection coatings both for photovoltaic applications and for mid-infrared optical elements. We have shown recently that selective ablation of such layers is possible using ultrashort laser pulses at wavelengths being absorbed by the semiconductor. To get a deeper understanding of the ablation mechanism, we have done ablation experiments for different transparent materials, in particular SiO2 and SixNy on silicon, using a broad range of wavelengths ranging from UV to IR, and pulse durations between 50 and 2000 fs. The characterization of the ablated regions was done by light microscopy and atomic force microscopy (AFM). Utilizing laser wavelengths above the silicon band gap, selective ablation of the dielectric layer without noticeable damage of the opened silicon surface is possible. In contrast, ultrashort pulses (1-2 ps) at mid-infrared wavelengths already cause damage in the silicon at lower intensities than in the dielectric layer, even when a vibrational resonance (e.g. at λ = 9.26 μm for SiO2) is addressed. The physical processes behind this, on the first glance counterintuitive, observation will be discussed.

  11. [Thermal balloon endometrial ablation for dysfunctional uterine bleeding: technical aspects and results. A prospective cohort study of 152 cases].

    PubMed

    Kdous, Moez; Jacob, Denis; Gervaise, Amélie; Risk, Elie; Sauvanet, Eric

    2008-05-01

    Thermal balloon endometrial ablation is a new operative technique recently proposed in the treatment of dysfunctional uterine bleeding. To evaluate the efficacy of thermal balloon endometrial ablation in the treatment of dysfunctional uterine bleeding, and to identify the possible predictive factors for a successful outcome. A prospective study was conducted including 152 patients with chronic abnormal uterine bleeding refractory to medical treatment. All patients were treated by thermal balloon endometrial ablation (Thermachoice, Gynecare) between January 1, 1996 and December 31, 2003. patients were included if their uterine cavities sounded to less than 12 cm and had undergone hysteroscopy, pelvic ultrasound and endometrial biopsie showing no structural or (pre) malignant endometrial abnormalities. A balloon catheter was placed through the cervix and after inflation in the endometrial cavity with 5% dextrose in water, was heated to 87 +/- 5 degrees C. No one required cervical dilatation. Balloon pressures were 160 to 170 mm Hg. All patients underwent 8 minutes of therapy. The average patient was 47 years (range: 30-62 years) and was followed for a mean of 3 years and 7 months (range: 6 months - 8 years). 31.6% of women reported amennorhea, 16.5% hypomenorrhea and 21% eumenorrhea. Menorrhagea persisted in 11.2% of patients. No intraoperative complications and minor postoperative morbidity occured in 10.5% of patients. Three prgnancy complicated by spontaneous abortions were reported after the treatment. A total of 78% of women reported overall satisfaction with the endometrial ablation procedure and 18% were dissatisfied. 17.8% of patients underwent hysterectomy within 1 to 5 years of balloon endometrial ablation. Increasing age and menopause were significantly associated with increased odds of success (p < 0.05). Thermal balloon endometrial ablation is a simple, easy, effective, and minimally invasive procedure in menhorragic women with no desire for further

  12. Experimental investigation of the laser ablation process on wood surfaces

    NASA Astrophysics Data System (ADS)

    Panzner, M.; Wiedemann, G.; Henneberg, K.; Fischer, R.; Wittke, Th.; Dietsch, R.

    1998-05-01

    Processing of wood by conventional mechanical tools like saws or planes leaves behind a layer of squeezed wood only slightly adhering to the solid wood surface. Laser ablation of this layer could improve the durability of coatings and glued joints. For technical applications, thorough knowledge about the laser ablation process is necessary. Results of ablation experiments by excimer lasers, Nd:YAG lasers, and TEA-CO 2 lasers on surfaces of different wood types and cut orientations are shown. The process of ablation was observed by a high-speed camera system and optical spectroscopy. The influence of the experimental parameters are demonstrated by SEM images and measurement of the ablation rate depending on energy density. Thermal effects like melting and also carbonizing of cellulose were found for IR- and also UV-laser wavelengths. Damage of the wood surface after laser ablation was weaker for excimer lasers and CO 2-TEA lasers. This can be explained by the high absorption of wood in the ultraviolet and middle infrared spectral range. As an additional result, this technique provides an easy way for preparing wood surfaces with excellently conserved cellular structure.

  13. Robotically assisted ablation produces more rapid and greater signal attenuation than manual ablation.

    PubMed

    Koa-Wing, Michael; Kojodjojo, Pipin; Malcolme-Lawes, Louisa C; Salukhe, Tushar V; Linton, Nick W F; Grogan, Aaron P; Bergman, Dale; Lim, Phang Boon; Whinnett, Zachary I; McCarthy, Karen; Ho, Siew Yen; O'Neill, Mark D; Peters, Nicholas S; Davies, D Wyn; Kanagaratnam, Prapa

    2009-12-01

    Robotic remote catheter ablation potentially provides improved catheter-tip stability, which should improve the efficiency of radiofrequency energy delivery. Percentage reduction in electrogram peak-to-peak voltage has been used as a measure of effectiveness of ablation. We tested the hypothesis that improved catheter-tip stability of robotic ablation can diminish signals to a greater degree than manual ablation. In vivo NavX maps of 7 pig atria were constructed. Separate lines of ablation were performed robotically and manually, recording pre- and postablation peak-to-peak voltages at 10, 20, 30, and 60 seconds and calculating signal amplitude reduction. Catheter ablation settings were constant (25W, 50 degrees , 17 mL/min, 20-30 g catheter tip pressure). The pigs were sacrificed and ablation lesions correlated with NavX maps. Robotic ablation reduced signal amplitude to a greater degree than manual ablation (49 +/- 2.6% vs 29 +/- 4.5% signal reduction after 1 minute [P = 0.0002]). The mean energy delivered (223 +/- 184 J vs 231 +/- 190 J, P = 0.42), power (19 +/- 3.5 W vs 19 +/- 4 W, P = 0.84), and duration of ablation (15 +/- 9 seconds vs 15 +/- 9 seconds, P = 0.89) was the same for manual and robotic. The mean peak catheter-tip temperature was higher for robotic (45 +/- 5 degrees C vs 42 +/- 3 degrees C [P < 0.0001]). The incidence of >50% signal reduction was greater for robotic (37%) than manual (21%) ablation (P = 0.0001). Robotically assisted ablation appears to be more effective than manual ablation at signal amplitude reduction, therefore may be expected to produce improved clinical outcomes.

  14. Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

    PubMed

    Wu, Po-Hung; Brace, Chris L

    2016-08-21

    Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal ablation. We hypothesized that contrast material delivered concurrently with thermal ablation may become trapped in the ablation zone, and set out to determine whether such an effect would impact ablation visualization. CECT images were acquired during microwave ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after ablation to evaluate whether contrast was trapped inside of the ablation zone. Visualization was compared between groups using post-ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the ablation boundary and background to quantitate ablation conspicuity. In Group A, attenuation decreased during ablation due to thermal expansion of tissue water and water vaporization. The ablation zone was difficult to visualize (CNR  =  1.57  ±  0.73, boundary gradient  =  0.7  ±  0.4 HU mm(-1)), leading to ablation diameter underestimation compared to gross pathology. Group B ablations saw attenuation increase, suggesting that iodine was trapped inside the ablation zone. However, because the normally perfused liver increased even more, Group B ablations were more visible than Group A (CNR  =  2.04  ±  0.84, boundary gradient  =  6.3  ±  1.1 HU mm(-1)) and allowed accurate estimation of the ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the ablation zone boundary was not highly visible (boundary gradient  =  3.9  ±  1.1 HU mm(-1)). Our results demonstrate that despite iodinated contrast being trapped in the ablation zone, ablation visibility

  15. Ablation enhancement of silicon by ultrashort double-pulse laser ablation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhao, Xin; Shin, Yung C.

    In this study, the ultrashort double-pulse ablation of silicon is investigated. An atomistic simulation model is developed to analyze the underlying physics. It is revealed that the double-pulse ablation could significantly increase the ablation rate of silicon, compared with the single pulse ablation with the same total pulse energy, which is totally different from the case of metals. In the long pulse delay range (over 1 ps), the enhancement is caused by the metallic transition of melted silicon with the corresponding absorption efficiency. At ultrashort pulse delay (below 1 ps), the enhancement is due to the electron excitation by the first pulse.more » The enhancement only occurs at low and moderate laser fluence. The ablation is suppressed at high fluence due to the strong plasma shielding effect.« less

  16. Magnetic Resonance Imaging-Guided High-Intensity Focused Ultrasound Ablation of Uterine Fibroids: Effect of Bowel Interposition on Procedure Feasibility and a Unique Bowel Displacement Technique.

    PubMed

    Kim, Young-Sun; Lim, Hyo Keun; Rhim, Hyunchul

    2016-01-01

    To evaluate the effect of bowel interposition on assessing procedure feasibility, and the usefulness and limiting conditions of bowel displacement techniques in magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) ablation of uterine fibroids. Institutional review board approved this study. A total of 375 screening MR exams and 206 MR-HIFU ablations for symptomatic uterine fibroids performed between August 2010 and March 2015 were retrospectively analyzed. The effect of bowel interposition on procedure feasibility was assessed by comparing pass rates in periods before and after adopting a unique bowel displacement technique (bladder filling, rectal filling and subsequent bladder emptying; BRB maneuver). Risk factors for BRB failure were evaluated using logistic regression analysis. Overall pass rates of pre- and post-BRB periods were 59.0% (98/166) and 71.7% (150/209), and in bowel-interposed cases they were 14.6% (7/48) and 76.4% (55/72), respectively. BRB maneuver was technically successful in 81.7% (49/60). Through-the-bladder sonication was effective in eight of eleven BRB failure cases, thus MR-HIFU could be initiated in 95.0% (57/60). A small uterus on treatment day was the only significant risk factor for BRB failure (B = 0.111, P = 0.017). The BRB maneuver greatly reduces the fraction of patients deemed ineligible for MR-HIFU ablation of uterine fibroids due to interposed bowels, although care is needed when the uterus is small.

  17. [Ablation on the undersurface of a LASIK flap. Instrument and method for continuous eye tracking].

    PubMed

    Taneri, S; Azar, D T

    2007-02-01

    The risk of iatrogenic keratectasia after laser in situ keratomileusis (LASIK) increases with thinner posterior stromal beds. Ablations on the undersurface of a LASIK flap could only be performed without the guidance of an eye tracker, which may lead to decentration. A new method for laser ablation with flying spot lasers on the undersurface of a LASIK flap was developed that enables the use of an active eye tracker by utilizing a novel instrument. The first clinical results are reported. Patients wishing an enhancement procedure were eligible for a modified repeat LASIK procedure if the flaps cut in the initial procedure were thick enough to perform the intended additional ablation on the undersurface leaving at least 90 microm of flap thickness behind. (1) The horizontal axis and the center of the entrance pupil were marked on the epithelial side of the flap using gentian violet dye. (2) The flap was reflected on a newly designed flap holder which had a donut-shaped black marking. (3) The eye tracker was centered on the mark visible in transparency on the flap. (4) Ablation with a flying spot Bausch & Lomb Technolas 217z laser was performed on the undersurface of the flap with a superior hinge taking into account that in astigmatic ablations the cylinder axis had to be mirrored according to the formula: axis on the undersurface=180 degrees -axis on the stromal bed. (5) The flap was repositioned. Detection of the marking on the modified flap holder and continuous tracking instead of the real pupil was possible in all of the 12 eyes treated with this technique. It may be necessary to cover the real pupil during ablation in order not to confuse the eye tracker. Ablation could be performed without decentration or loss of best spectacle-corrected visual acuity. Refractive results in minor corrections were good without nomogram adjustment. Using this novel flap holder with a marking that is tracked instead of the real pupil, centered ablations with a flying spot laser

  18. Intraoperative microwave ablation of pulmonary malignancies with tumor permittivity feedback control: ablation and resection study in 10 consecutive patients.

    PubMed

    Wolf, Farrah J; Aswad, Bassam; Ng, Thomas; Dupuy, Damian E

    2012-01-01

    To determine histologic changes induced by microwave ablation (MWA) in patients with pulmonary malignancy by using an ablation system with tumor permittivity feedback control, enabling real-time modulation of energy power and frequency. Institutional review board approval and patient informed consent were obtained for this prospective HIPAA-complaint ablation and resection study. Between March 2009 and January 2010, 10 patients (four women, six men; mean age, 71 years; age range, 52-82 years) underwent intraoperative MWA of pulmonary malignancies. Power (10-32 W) and frequency (908-928 MHz) were continuously adjusted by the generator to maintain a temperature of 110°-120°C at the 14-gauge antenna tip for one 10-minute application. After testing for an air leak, tumors were resected surgically. Gross inspection, slicing, and hematoxylin-eosin (10 specimens) and nicotinamide adenine dinucleotide (six specimens) staining were performed. Tumors included adenocarcinomas (n = 5), squamous cell carcinomas (n = 3), and metastases from endometrial (n = 1) and colorectal (n = 1) primary carcinomas. Mean maximum tumor diameter was 2.4 cm (range, 0.9-5.0 cm), and mean maximum volume was 8.6 cm(3) (range, 0.5-52.7 cm(3)). One air leak was detected. Five of 10 specimens were grossly measurable, revealing a mean maximum ablation zone diameter of 4.8 cm (range, 3.0-6.5 cm) and a mean maximum ablation zone volume of 15.1 cm(3) (range, 7.3-25.1 cm(3)). At hematoxylin-eosin staining, coagulation necrosis was observed in all ablation zones, extended into the normal lung in nine of 10 specimens, and up to blood vessel walls without evidence of vessel (>4 mm) thrombosis. Nicotinamide adenine dinucleotide staining enabled confirmation of no viability within ablation zones extending into normal lung in five of six specimens. MWA with tumor permittivity feedback control results in cytotoxic intratumoral temperatures and extension of ablation zones into aerated peritumoral pulmonary

  19. Endometrial Ablation

    MedlinePlus

    ... or lighter levels. If ablation does not control heavy bleeding, further treatment or surgery may be needed. ... ablation is used to treat many causes of heavy bleeding. In most cases, women with heavy bleeding ...

  20. Systematic review of ablative neurosurgical techniques for the treatment of trigeminal neuralgia.

    PubMed

    Lopez, Benjamin C; Hamlyn, Peter J; Zakrzewska, Joanna M

    2004-04-01

    There are no randomized controlled trials comparing retrogasserian percutaneous radiofrequency thermocoagulation, glycerol rhizolysis, balloon compression of the gasserian ganglion, and stereotactic radiosurgery, nor are there systematic reviews using predefined quality criteria. The objective of this study was to systematically identify all of the studies reporting outcomes and complications of ablative techniques for treatment of trigeminal neuralgia, from the development of electronic databases, and to evaluate them with predefined quality criteria. Inclusion criteria for the outcome analysis included thorough demographic documentation, defined diagnostic and outcome criteria, a minimum of 30 patients treated and median/mean follow-up times of 12 months, not more than 20% of patients lost to follow-up monitoring, Kaplan-Meier actuarial analysis of individual procedures, less than 10% of patients retreated because of failure or early recurrence, and a minimal dose of 70 Gy for stereotactic radiosurgery. High-quality studies with no actuarial analysis were used for the evaluation of complications. Of 175 studies identified, 9 could be used to evaluate rates of complete pain relief on a yearly basis and 22 could be used to evaluate complications. In mixed series, radiofrequency thermocoagulation offered higher rates of complete pain relief, compared with glycerol rhizolysis and stereotactic radiosurgery, although it demonstrated the greatest number of complications. Radiofrequency thermocoagulation offers the highest rates of complete pain relief, although further data on balloon microcompression are required. It is essential that uniform outcome measures and actuarial methods be universally adopted for the reporting of surgical results. Randomized controlled trials are required to reliably evaluate new surgical techniques.

  1. 2D shear-wave ultrasound elastography (SWE) evaluation of ablation zone following radiofrequency ablation of liver lesions: is it more accurate?

    PubMed Central

    Bo, Xiao W; Li, Xiao L; Guo, Le H; Li, Dan D; Liu, Bo J; Wang, Dan; He, Ya P; Xu, Xiao H

    2016-01-01

    (all p > 0.05). Conclusion: The quantitative 2D-SWE of VTIQ is useful for the depiction of the ablation zone after RFA and it facilitates discrimination of different areas in the ablation zone qualitatively and quantitatively. This elastography technique might be useful for the therapeutic response evaluation instantly after RFA. Advances in knowledge: A new quantitative 2D-SWE (i.e. VTIQ) for evaluation treatment response after RFA is demonstrated. It facilitates discrimination of the different areas in the ablation zone qualitatively and quantitatively and may be useful for the therapeutic response evaluation instantly after RFA in the future. PMID:26933911

  2. Low temperature ablation models made by pressure/vacuum application

    NASA Technical Reports Server (NTRS)

    Fischer, M. C.; Heier, W. C.

    1970-01-01

    Method developed employs high pressure combined with strong vacuum force to compact ablation models into desired conical shape. Technique eliminates vapor hazard and results in high material density providing excellent structural integrity.

  3. Toward standardized mapping for left atrial analysis and cardiac ablation guidance

    NASA Astrophysics Data System (ADS)

    Rettmann, M. E.; Holmes, D. R.; Linte, C. A.; Packer, D. L.; Robb, R. A.

    2014-03-01

    In catheter-based cardiac ablation, the pulmonary vein ostia are important landmarks for guiding the ablation procedure, and for this reason, have been the focus of many studies quantifying their size, structure, and variability. Analysis of pulmonary vein structure, however, has been limited by the lack of a standardized reference space for population based studies. Standardized maps are important tools for characterizing anatomic variability across subjects with the goal of separating normal inter-subject variability from abnormal variability associated with disease. In this work, we describe a novel technique for computing flat maps of left atrial anatomy in a standardized space. A flat map of left atrial anatomy is created by casting a single ray through the volume and systematically rotating the camera viewpoint to obtain the entire field of view. The technique is validated by assessing preservation of relative surface areas and distances between the original 3D geometry and the flat map geometry. The proposed methodology is demonstrated on 10 subjects which are subsequently combined to form a probabilistic map of anatomic location for each of the pulmonary vein ostia and the boundary of the left atrial appendage. The probabilistic map demonstrates that the location of the inferior ostia have higher variability than the superior ostia and the variability of the left atrial appendage is similar to the superior pulmonary veins. This technique could also have potential application in mapping electrophysiology data, radio-frequency ablation burns, or treatment planning in cardiac ablation therapy.

  4. [Evaluation and results of ablative therapies in prostate cancer].

    PubMed

    Renard-Penna, R; Sanchez-Salas, R; Barret, E; Cosset, J M; de Vergie, S; Sapetti, J; Ingels, A; Gangi, A; Lang, H; Cathelineau, X

    2017-11-01

    To perform a state of the art about methods of evaluation and present results in ablative therapies for localized prostate cancer. A review of the scientific literature was performed in Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of keywords. Publications obtained were selected based on methodology, language and relevance. After selection, 102 articles were analysed. Analyse the results of ablative therapies is presently difficult considering the heterogeneity of indications, techniques and follow-up. However, results from the most recent and homogeneous studies are encouraging. Oncologically, postoperative biopsies (the most important criteria) are negative (without any tumor cells in the treated area) in 75 to 95%. Functionally, urinary and sexual pre-operative status is spared (or recovered early) in more than 90% of the patients treated. More and more studies underline also the correlation between the results and the technique used considering the volume of the gland and, moreover, the "index lesion" localization. The post-treatment pathological evaluation by biopsies (targeted with MRI or, perhaps in a near future, with innovative ultrasonography) is the corner stone of oncological evaluation of ablative therapies. Ongoing trials will allow to standardize the follow-up and determine the best indication and the best techniques in order to optimize oncological and functional results for each patient treated. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  5. Modeling and estimation of tip contact force for steerable ablation catheters.

    PubMed

    Khoshnam, Mahta; Skanes, Allan C; Patel, Rajni V

    2015-05-01

    The efficacy of catheter-based cardiac ablation procedures can be significantly improved if real-time information is available concerning contact forces between the catheter tip and cardiac tissue. However, the widely used ablation catheters are not equipped for force sensing. This paper proposes a technique for estimating the contact forces without direct force measurements by studying the changes in the shape of the deflectable distal section of a conventional 7-Fr catheter (henceforth called the "deflectable distal shaft," the "deflectable shaft," or the "shaft" of the catheter) in different loading situations. First, the shaft curvature when the tip is moving in free space is studied and based on that, a kinematic model for the deflectable shaft in free space is proposed. In the next step, the shaft shape is analyzed in the case where the tip is in contact with the environment, and it is shown that the curvature of the deflectable shaft provides useful information about the loading status of the catheter and can be used to define an index for determining the range of contact forces exerted by the ablation tip. Experiments with two different steerable ablation catheters show that the defined index can detect the range of applied contact forces correctly in more than 80% of the cases. Based on the proposed technique, a framework for obtaining contact force information by using the shaft curvature at a limited number of points along the deflectable shaft is constructed. The proposed kinematic model and the force estimation technique can be implemented together to describe the catheter's behavior before contact, detect tip/tissue contact, and determine the range of contact forces. This study proves that the flexibility of the catheter's distal shaft provides a means of estimating the force exerted on tissue by the ablation tip.

  6. Assessment of Ablative Therapies in Swine: Response of Respiratory Diaphragm to Varying Doses.

    PubMed

    Singal, Ashish; Mattison, Lars M; Soule, Charles L; Ballard, John R; Rudie, Eric N; Cressman, Erik N K; Iaizzo, Paul A

    2018-03-28

    Ablation is a common procedure for treating patients with cancer, cardiac arrhythmia, and other conditions, yet it can cause collateral injury to the respiratory diaphragm. Collateral injury can alter the diaphragm's properties and/or lead to respiratory dysfunction. Thus, it is important to understand the diaphragm's physiologic and biomechanical properties in response to ablation therapies, in order to better understand ablative modalities, minimize complications, and maximize the safety and efficacy of ablative procedures. In this study, we analyzed physiologic and biomechanical properties of swine respiratory diaphragm muscle bundles when exposed to 5 ablative modalities. To assess physiologic properties, we performed in vitro tissue bath studies and measured changes in peak force and baseline force. To assess biomechanical properties, we performed uniaxial stress tests, measuring force-displacement responses, stress-strain characteristics, and avulsion forces. After treating the muscle bundles with all 5 ablative modalities, we observed dose-dependent sustained reductions in peak force and transient increases in baseline force-but no consistent dose-dependent biomechanical responses. These data provide novel insights into the effects of various ablative modalities on the respiratory diaphragm, insights that could enable improvements in ablative techniques and therapies.

  7. Radiofrequency ablation for hepatic hemangiomas: A consensus from a Chinese panel of experts

    PubMed Central

    Gao, Jun; Fan, Rui-Fang; Yang, Jia-Yin; Cui, Yan; Ji, Jian-Song; Ma, Kuan-Sheng; Li, Xiao-Long; Zhang, Long; Xu, Chong-Liang; Kong, Xin-Liang; Ke, Shan; Ding, Xue-Mei; Wang, Shao-Hong; Yang, Meng-Meng; Song, Jin-Jin; Zhai, Bo; Nin, Chun-Ming; Guo, Shi-Gang; Xin, Zong-Hai; Lu, Jun; Dong, Yong-Hong; Zhu, Hua-Qiang; Sun, Wen-Bing

    2017-01-01

    Recent studies have shown that radiofrequency (RF) ablation therapy is a safe, feasible, and effective procedure for hepatic hemangiomas, even huge hepatic hemangiomas. RF ablation has the following advantages in the treatment of hepatic hemangiomas: minimal invasiveness, definite efficacy, high safety, fast recovery, relatively simple operation, and wide applicability. It is necessary to formulate a widely accepted consensus among the experts in China who have extensive expertise and experience in the treatment of hepatic hemangiomas using RF ablation, which is important to standardize the application of RF ablation for the management of hepatic hemangiomas, regarding the selection of patients with suitable indications to receive RF ablation treatment, the technical details of the techniques, therapeutic effect evaluations, management of complications, etc. A final consensus by a Chinese panel of experts who have the expertise of using RF ablation to treat hepatic hemangiomas was reached by means of literature review, comprehensive discussion, and draft approval. PMID:29093616

  8. Low-threshold ablation of enamel and dentin using Nd:YAG laser assisted with chromophore with different pulse shapes

    NASA Astrophysics Data System (ADS)

    Bonora, Stefano; Benazzato, Paolo; Stefani, Alessandro; Villoresi, Paolo

    2004-05-01

    Neodimium laser treatment has several drawbacks when used in the hard tissue cutting, because of the low absorption of the dental tissues at its wavelength. This investigation proved that the Nd:YAG radiation is a powerful ablation tool if it is used with the dye assisted method. Several in vitro tests on enamel and dentin were accomplished changing some laser parameters to have different pulse shapes and durations from 125μs up to 1.4ms. The importance of short time high power peaks, typical of crystal lasers, in the ablation process was investigated. The pulse shapes were analyzed by their intensity in space and time profiles. A first set of results found the optimum dye concentration be used in all the following tests. Furthermore the ablation threshold for this technique was found for each different pulse shapes and durations. A low energy ablation method was found to avoid temperature increase and surface cracks formation. In vitro temperature analysis was reported comparing the differences between no dye application laser treatment and with a dye spray applied. A strong reduction of the temperature increase was found in the dye assisted method. A discussion on the general findings and their possible clinical applications is presented.

  9. Specific Impulse Definition for Ablative Laser Propulsion

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Gregory, Don A.

    2004-01-01

    The term "specific impulse" is so ingrained in the field of rocket propulsion that it is unlikely that any fundamental argument would be taken seriously for its removal. It is not an ideal measure but it does give an indication of the amount of mass flow (mass loss/time), as in fuel rate, required to produce a measured thrust over some time period This investigation explores the implications of being able to accurately measure the ablation rate and how the language used to describe the specific impulse results may have to change slightly, and recasts the specific impulse as something that is not a time average. It is not currently possible to measure the ablation rate accurately in real time so it is generally just assumed that a constant amount of material will be removed for each laser pulse delivered The specific impulse dependence on the ablation rate is determined here as a correction to the classical textbook definition.

  10. Orbit Modification of Earth-Crossing Asteroids/Comets Using Rendezvous Spacecraft and Laser Ablation

    NASA Technical Reports Server (NTRS)

    Park, Sang-Young; Mazanek, Daniel D.

    2005-01-01

    This report describes the approach and results of an end-to-end simulation to deflect a long-period comet (LPC) by using a rapid rendezvous spacecraft and laser ablation system. The laser energy required for providing sufficient deflection DELTA V and an analysis of possible intercept/rendezvous spacecraft trajectories are studied in this analysis. These problems minimize a weighted sum of the flight time and required propellant by using an advanced propulsion system. The optimal thrust-vector history and propellant mass to use are found in order to transfer a spacecraft from the Earth to a targeted celestial object. One goal of this analysis is to formulate an optimization problem for intercept/rendezvous spacecraft trajectories. One approach to alter the trajectory of the object in a highly controlled manner is to use pulsed laser ablative propulsion. A sufficiently intense laser pulse ablates the surface of a near-Earth object (NEO) by causing plasma blowoff. The momentum change from a single laser pulse is very small. However, the cumulative effect is very effective because the laser can interact with the object over long periods of time. The laser ablation technique can overcome the mass penalties associated with other nondisruptive approaches because no propellant is required to generate the DELTA V (the material of the celestial object is the propellant source). Additionally, laser ablation is effective against a wide range of surface materials and does not require any landing or physical attachment to the object. For diverting distant asteroids and comets, the power and optical requirements of a laser ablation system on or near the Earth may be too extreme to contemplate in the next few decades. A hybrid solution would be for a spacecraft to carry a laser as a payload to a particular celestial body. The spacecraft would require an advanced propulsion system capable of rapid rendezvous with the object and an extremely powerful electrical generator, which is

  11. Improving Thermal Ablation Delineation With Electrode Vibration Elastography Using a Bidirectional Wave Propagation Assumption

    PubMed Central

    DeWall, Ryan J.; Varghese, Tomy

    2013-01-01

    Thermal ablation procedures are commonly used to treat hepatic cancers and accurate ablation representation on shear wave velocity images is crucial to ensure complete treatment of the malignant target. Electrode vibration elastography is a shear wave imaging technique recently developed to monitor thermal ablation extent during treatment procedures. Previous work has shown good lateral boundary delineation of ablated volumes, but axial delineation was more ambiguous, which may have resulted from the assumption of lateral shear wave propagation. In this work, we assume both lateral and axial wave propagation and compare wave velocity images to those assuming only lateral shear wave propagation in finite element simulations, tissue-mimicking phantoms, and bovine liver tissue. Our results show that assuming bidirectional wave propagation minimizes artifacts above and below ablated volumes, yielding a more accurate representation of the ablated region on shear wave velocity images. Area overestimation was reduced from 13.4% to 3.6% in a stiff-inclusion tissue-mimicking phantom and from 9.1% to 0.8% in a radio-frequency ablation in bovine liver tissue. More accurate ablation representation during ablation procedures increases the likelihood of complete treatment of the malignant target, decreasing tumor recurrence. PMID:22293748

  12. Improving thermal ablation delineation with electrode vibration elastography using a bidirectional wave propagation assumption.

    PubMed

    DeWall, Ryan J; Varghese, Tomy

    2012-01-01

    Thermal ablation procedures are commonly used to treat hepatic cancers and accurate ablation representation on shear wave velocity images is crucial to ensure complete treatment of the malignant target. Electrode vibration elastography is a shear wave imaging technique recently developed to monitor thermal ablation extent during treatment procedures. Previous work has shown good lateral boundary delineation of ablated volumes, but axial delineation was more ambiguous, which may have resulted from the assumption of lateral shear wave propagation. In this work, we assume both lateral and axial wave propagation and compare wave velocity images to those assuming only lateral shear wave propagation in finite element simulations, tissue-mimicking phantoms, and bovine liver tissue. Our results show that assuming bidirectional wave propagation minimizes artifacts above and below ablated volumes, yielding a more accurate representation of the ablated region on shear wave velocity images. Area overestimation was reduced from 13.4% to 3.6% in a stiff-inclusion tissue-mimicking phantom and from 9.1% to 0.8% in a radio-frequency ablation in bovine liver tissue. More accurate ablation representation during ablation procedures increases the likelihood of complete treatment of the malignant target, decreasing tumor recurrence. © 2012 IEEE

  13. Image-based modeling and characterization of RF ablation lesions in cardiac arrhythmia therapy

    NASA Astrophysics Data System (ADS)

    Linte, Cristian A.; Camp, Jon J.; Rettmann, Maryam E.; Holmes, David R.; Robb, Richard A.

    2013-03-01

    In spite of significant efforts to enhance guidance for catheter navigation, limited research has been conducted to consider the changes that occur in the tissue during ablation as means to provide useful feedback on the progression of therapy delivery. We propose a technique to visualize lesion progression and monitor the effects of the RF energy delivery using a surrogate thermal ablation model. The model incorporates both physical and physiological tissue parameters, and uses heat transfer principles to estimate temperature distribution in the tissue and geometry of the generated lesion in near real time. The ablation model has been calibrated and evaluated using ex vivo beef muscle tissue in a clinically relevant ablation protocol. To validate the model, the predicted temperature distribution was assessed against that measured directly using fiberoptic temperature probes inserted in the tissue. Moreover, the model-predicted lesions were compared to the lesions observed in the post-ablation digital images. Results showed an agreement within 5°C between the model-predicted and experimentally measured tissue temperatures, as well as comparable predicted and observed lesion characteristics and geometry. These results suggest that the proposed technique is capable of providing reasonably accurate and sufficiently fast representations of the created RF ablation lesions, to generate lesion maps in near real time. These maps can be used to guide the placement of successive lesions to ensure continuous and enduring suppression of the arrhythmic pathway.

  14. Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tanaka, Toshihiro, E-mail: toshihir@bf6.so-net.ne.jp; Westphal, Saskia, E-mail: swestphal@ukaachen.de; Isfort, Peter, E-mail: isfort@hia.rwth-aachen.de

    2012-08-15

    Purpose: To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue. Materials and Methods: MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation. Results: The mean short-axis diameters of the coagulation zones were 1.34 {+-} 0.14, 1.45 {+-} 0.13, and 1.74 {+-} 0.11 cm for MWmore » ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 {+-} 0.09 and 1.26 {+-} 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 {+-} 0.65, 2.85 {+-} 0.72, and 4.45 {+-} 0.47 cm{sup 3} for MW ablation at outputs of 25W, 35W, and 45W and 1.18 {+-} 0.30 and 2.29 {+-} 0.55 cm{sup 3} got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature was achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations. Conclusion: MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.« less

  15. Effects of material composition on the ablation performance of low density elastomeric ablators

    NASA Technical Reports Server (NTRS)

    Tompkins, S. S.; Kabana, W. P.

    1973-01-01

    The ablation performance of materials composed of various concentrations of nylon, hollow silica spheres, hollow phenolic spheres, and four elastomeric resins was determined. Both blunt-body and flat-panel specimens were used, the cold-wall heating-rate ranges being 0.11 to 0.8 MW/sq m, respectively. The corresponding surface pressure ranges for these tests were 0.017 to 0.037 atmosphere and 0.004 to 0.005 atmosphere. Some of the results show that (1) the addition of nylon significantly improved the ablation performance, but the nylon was not compatible with one resin system; (2) panel and blunt-body specimen data do not show the same effect of phenolic sphere content on ablation effectiveness; and (3) there appears to be an optimum concentration of hollow silica spheres for good ablation performance. The composition of an efficient, nonproprietary ablator for lifting body application is identified and the ablation performance of this ablator is compared with the performance of three commercially available materials.

  16. Optical feedback-induced light modulation for fiber-based laser ablation.

    PubMed

    Kang, Hyun Wook

    2014-11-01

    Optical fibers have been used as a minimally invasive tool in various medical fields. However, due to excessive heat accumulation, the distal end of a fiber often suffers from severe melting or devitrification, leading to the eventual fiber failure during laser treatment. In order to minimize thermal damage at the fiber tip, an optical feedback sensor was developed and tested ex vivo. Porcine kidney tissue was used to evaluate the feasibility of optical feedback in terms of signal activation, ablation performance, and light transmission. Testing various signal thresholds demonstrated that 3 V was relatively appropriate to trigger the feedback sensor and to prevent the fiber deterioration during kidney tissue ablation. Based upon the development of temporal signal signatures, full contact mode rapidly activated the optical feedback sensor possibly due to heat accumulation. Modulated light delivery induced by optical feedback diminished ablation efficiency by 30% in comparison with no feedback case. However, long-term transmission results validated that laser ablation assisted with optical feedback was able to almost consistently sustain light delivery to the tissue as well as ablation efficiency. Therefore, an optical feedback sensor can be a feasible tool to protect optical fiber tips by minimizing debris contamination and delaying thermal damage process and to ensure more efficient and safer laser-induced tissue ablation.

  17. Femtosecond laser ablation of dentin and enamel: relationship between laser fluence and ablation efficiency.

    PubMed

    Chen, Hu; Liu, Jing; Li, Hong; Ge, Wenqi; Sun, Yuchun; Wang, Yong; Lü, Peijun

    2015-02-01

    The objective was to study the relationship between laser fluence and ablation efficiency of a femtosecond laser with a Gaussian-shaped pulse used to ablate dentin and enamel for prosthodontic tooth preparation. A diode-pumped thin-disk femtosecond laser with wavelength of 1025 nm and pulse width of 400 fs was used for the ablation of dentin and enamel. The laser spot was guided in a line on the dentin and enamel surfaces to form a groove-shaped ablation zone under a series of laser pulse energies. The width and volume of the ablated line were measured under a three-dimensional confocal microscope to calculate the ablation efficiency. Ablation efficiency for dentin reached a maximum value of 0.020 mm3∕J when the laser fluence was set at 6.51 J∕cm2. For enamel, the maximum ablation efficiency was 0.009 mm3∕J at a fluence of 7.59 J∕cm2.Ablation efficiency of the femtosecond laser on dentin and enamel is closely related to the laser fluence and may reach a maximum when the laser fluence is set to an appropriate value. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

  18. Morphology and mechanisms of picosecond ablation of metal films on fused silica substrates

    NASA Astrophysics Data System (ADS)

    Bass, Isaac L.; Negres, Raluca A.; Stanion, Ken; Guss, Gabe; Keller, Wesley J.; Matthews, Manyalibo J.; Rubenchik, Alexander M.; Yoo, Jae Hyuck; Bude, Jeffrey D.

    2016-12-01

    The ablation of magnetron sputtered metal films on fused silica substrates by a 1053 nm, picosecond class laser was studied as part of a demonstration of its use for in-situ characterization of the laser spot under conditions commonly used at the sample plane for laser machining and damage studies. Film thicknesses were 60 and 120 nm. Depth profiles and SEM images of the ablation sites revealed several striking and unexpected features distinct from those typically observed for ablation of bulk metals. Very sharp thresholds were observed for both partial and complete ablation of the films. Partial film ablation was largely independent of laser fluence with a surface smoothness comparable to that of the unablated surface. Clear evidence of material displacement was seen at the boundary for complete film ablation. These features were common to a number of different metal films including Inconel on commercial neutral density filters, stainless steel, and aluminum. We will present data showing the morphology of the ablation sites on these films as well as a model of the possible physical mechanisms producing the unique features observed.

  19. Localization of gaps during redo ablations of paroxysmal atrial fibrillation: Preferential patterns depending on the choice of cryoballoon ablation or radiofrequency ablation for the initial procedure.

    PubMed

    Galand, Vincent; Pavin, Dominique; Behar, Nathalie; Auffret, Vincent; Fénéon, Damien; Behaghel, Albin; Daubert, Jean-Claude; Mabo, Philippe; Martins, Raphaël P

    2016-11-01

    Pulmonary vein (PV) isolation, using cryoballoon or radiofrequency ablation, is the cornerstone therapy for symptomatic paroxysmal atrial fibrillation (AF) refractory to antiarrhythmic drugs. One-third of the patients have recurrences, mainly due to PV reconnections. To describe the different locations of reconnection sites in patients who had previously undergone radiofrequency or cryoballoon ablation, and to compare the characteristics of the redo procedures in both instances. Demographic data and characteristics of the initial ablation (cryoballoon or radiofrequency) were collected. Number and localization of reconduction gaps, and redo characteristics were reviewed. Seventy-four patients scheduled for a redo ablation of paroxysmal AF were included; 38 had been treated by radiofrequency ablation and 36 by cryoballoon ablation during the first procedure. For the initial ablation, procedural and fluoroscopy times were significantly shorter for cryoballoon ablation (147.8±52.6min vs. 226.6±64.3min [P<0.001] and 37.0±17.7min vs. 50.8±22.7min [P=0.005], respectively). Overall, an identical number of gaps was found during redo procedures of cryoballoon and radiofrequency ablations. However, a significantly higher number of gaps were located in the right superior PV for patients first ablated with radiofrequency (0.9±1.0 vs. 0.5±0.9; P=0.009). Gap localization displayed different patterns. Although not significant, redo procedures of cryoballoon ablation were slightly shorter and needed shorter durations of radiofrequency to achieve PV isolation. During redo procedures, gap localization pattern is different for patients first ablated with cryoballoon or radiofrequency ablation, and right superior PV reconnections occur more frequently after radiofrequency ablation. Redo ablation of a previous cryoballoon ablation appears to be easier. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  20. Stereotactic Laser Ablation for Medically Intractable Epilepsy: The Next Generation of Minimally Invasive Epilepsy Surgery

    PubMed Central

    LaRiviere, Michael J.; Gross, Robert E.

    2016-01-01

    Epilepsy is a common, disabling illness that is refractory to medical treatment in approximately one-third of patients, particularly among those with mesial temporal lobe epilepsy. While standard open mesial temporal resection is effective, achieving seizure freedom in most patients, efforts to develop safer, minimally invasive techniques have been underway for over half a century. Stereotactic ablative techniques, in particular, radiofrequency (RF) ablation, were first developed in the 1960s, with refinements in the 1990s with the advent of modern computed tomography and magnetic resonance-based imaging. In the past 5 years, the most recent techniques have used MRI-guided laser interstitial thermotherapy (LITT), the development of which began in the 1980s, saw refinements in MRI thermal imaging through the 1990s, and was initially used primarily for the treatment of intracranial and extracranial tumors. The present review describes the original stereotactic ablation trials, followed by modern imaging-guided RF ablation series for mesial temporal lobe epilepsy. The developments of LITT and MRI thermometry are then discussed. Finally, the two currently available MRI-guided LITT systems are reviewed for their role in the treatment of mesial temporal lobe and other medically refractory epilepsies. PMID:27995127

  1. Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling

    NASA Astrophysics Data System (ADS)

    Donnarumma, Fabrizio; Camp, Eden E.; Cao, Fan; Murray, Kermit K.

    2017-09-01

    Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. [Figure not available: see fulltext.

  2. Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling.

    PubMed

    Donnarumma, Fabrizio; Camp, Eden E; Cao, Fan; Murray, Kermit K

    2017-09-01

    Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. Graphical Abstract ᅟ.

  3. Caries selective ablation: the handpiece

    NASA Astrophysics Data System (ADS)

    Hennig, Thomas; Rechmann, Peter; Holtermann, Andreas

    1995-05-01

    Caries selective ablation is fixed to a window of fluences predicted by the ablation thresholds of carious and healthy dentin, respectively. The aim of the study was to develop a dental handpiece which guarantees homogeneous fluence at the irradiated tooth surface. Furthermore the point of treatment should be cooled down without energy losses due to the cooling system. We suggest the direct coupling of the laser radiation into a laminar stream of liquid, which acts in turn as a lengthened beam guide. The impacts of the laser radiation and of the cooling medium fall exactly into the same point. Hot ablation debris is removed out of the crater by the flush of the water jet. Fluences are constant if the handpiece is used in contact mode or at a distance. Normally the surface of a bare fiber working in contact mode is destroyed after a few shots. Coupling the laser radiation into a stream of liquid prevents this destruction. Putting together the benefits of this special handpiece short overall treatment times seem to be possible. High average power can be applied to the tooth without the threat of thermal damage. Furthermore no time consuming cutting of the fiber prolongs the treatment time.

  4. Voltage and pace-capture mapping of linear ablation lesions overestimates chronic ablation gap size.

    PubMed

    O'Neill, Louisa; Harrison, James; Chubb, Henry; Whitaker, John; Mukherjee, Rahul K; Bloch, Lars Ølgaard; Andersen, Niels Peter; Dam, Høgni; Jensen, Henrik K; Niederer, Steven; Wright, Matthew; O'Neill, Mark; Williams, Steven E

    2018-04-26

    Conducting gaps in lesion sets are a major reason for failure of ablation procedures. Voltage mapping and pace-capture have been proposed for intra-procedural identification of gaps. We aimed to compare gap size measured acutely and chronically post-ablation to macroscopic gap size in a porcine model. Intercaval linear ablation was performed in eight Göttingen minipigs with a deliberate gap of ∼5 mm left in the ablation line. Gap size was measured by interpolating ablation contact force values between ablation tags and thresholding at a low force cut-off of 5 g. Bipolar voltage mapping and pace-capture mapping along the length of the line were performed immediately, and at 2 months, post-ablation. Animals were euthanized and gap sizes were measured macroscopically. Voltage thresholds to define scar were determined by receiver operating characteristic analysis as <0.56 mV (acutely) and <0.62 mV (chronically). Taking the macroscopic gap size as gold standard, error in gap measurements were determined for voltage, pace-capture, and ablation contact force maps. All modalities overestimated chronic gap size, by 1.4 ± 2.0 mm (ablation contact force map), 5.1 ± 3.4 mm (pace-capture), and 9.5 ± 3.8 mm (voltage mapping). Error on ablation contact force map gap measurements were significantly less than for voltage mapping (P = 0.003, Tukey's multiple comparisons test). Chronically, voltage mapping and pace-capture mapping overestimated macroscopic gap size by 11.9 ± 3.7 and 9.8 ± 3.5 mm, respectively. Bipolar voltage and pace-capture mapping overestimate the size of chronic gap formation in linear ablation lesions. The most accurate estimation of chronic gap size was achieved by analysis of catheter-myocardium contact force during ablation.

  5. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    NASA Astrophysics Data System (ADS)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Döbeli, Max; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas

    2015-10-01

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially 18O substituted La0.6Sr0.4MnO3 target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures.

  6. Analysis of internal ablation for the thermal control of aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Camberos, Jose A.; Roberts, Leonard

    1989-01-01

    A new method of thermal protection for transatmospheric vehicles is introduced. The method involves the combination of radiation, ablation and transpiration cooling. By placing an ablating material behind a fixed-shape, porous outer shield, the effectiveness of transpiration cooling is made possible while retaining the simplicity of a passive mechanism. A simplified one-dimensional approach is used to derive the governing equations. Reduction of these equations to non-dimensional form yields two parameters which characterize the thermal protection effectiveness of the shield and ablator combination for a given trajectory. The non-dimensional equations are solved numerically for a sample trajectory corresponding to glide re-entry. Four typical ablators are tested and compared with results obtained by using the thermal properties of water. For the present level of analysis, the numerical computations adequately support the analytical model.

  7. Ablation for Atrial Fibrillation

    PubMed Central

    2006-01-01

    Executive Summary Objective To review the effectiveness, safety, and costing of ablation methods to manage atrial fibrillation (AF). The ablation methods reviewed were catheter ablation and surgical ablation. Clinical Need Atrial fibrillation is characterized by an irregular, usually rapid, heart rate that limits the ability of the atria to pump blood effectively to the ventricles. Atrial fibrillation can be a primary diagnosis or it may be associated with other diseases, such as high blood pressure, abnormal heart muscle function, chronic lung diseases, and coronary heart disease. The most common symptom of AF is palpitations. Symptoms caused by decreased blood flow include dizziness, fatigue, and shortness of breath. Some patients with AF do not experience any symptoms. According to United States data, the incidence of AF increases with age, with a prevalence of 1 per 200 people aged between 50 and 60 years, and 1 per 10 people aged over 80 years. In 2004, the Institute for Clinical Evaluative Sciences (ICES) estimated that the rate of hospitalization for AF in Canada was 582.7 per 100,000 population. They also reported that of the patients discharged alive, 2.7% were readmitted within 1 year for stroke. One United States prevalence study of AF indicated that the overall prevalence of AF was 0.95%. When the results of this study were extrapolated to the population of Ontario, the prevalence of AF in Ontario is 98,758 for residents aged over 20 years. Currently, the first-line therapy for AF is medical therapy with antiarrhythmic drugs (AADs). There are several AADs available, because there is no one AAD that is effective for all patients. The AADs have critical adverse effects that can aggravate existing arrhythmias. The drug selection process frequently involves trial and error until the patient’s symptoms subside. The Technology Ablation has been frequently described as a “cure” for AF, compared with drug therapy, which controls AF but does not cure it

  8. Primary malignant tumours of the bony pelvis: US-guided high intensity focused ultrasound ablation.

    PubMed

    Wang, Yang; Wang, Wei; Tang, Jie

    2013-11-01

    The aim of this review is to evaluate the value of ultrasound (US)-guided high intensity focused ultrasound (HIFU) ablation in the treatment of primary malignant tumours of the bony pelvis. Eleven patients with primary malignant tumours of the bony pelvis received US-guided HIFU ablation. The maximum tumour size ranged from 5.6 to 25.0 cm (median 10.5 cm). Treatment was curative in four patients and palliative in seven patients. During follow-up, the effectiveness of HIFU ablation was assessed by contrast-enhanced magnetic resonance (MR). Significant coagulative necrosis was obtained in all patients after scheduled HIFU ablations; the volume ablation ratio was 86.7% ± 12.5% (range 65-100%). Complete tumour necrosis was achieved in all patients receiving curative HIFU ablation. No major complications were encountered. No patients died of local tumour progression during follow-up. US-guided HIFU ablation may be a safe and effective minimally invasive technique for the local treatment of primary malignant tumours of the bony pelvis.

  9. Setup for functional cell ablation with lasers: coupling of a laser to a microscope.

    PubMed

    Sweeney, Sean T; Hidalgo, Alicia; de Belle, J Steven; Keshishian, Haig

    2012-06-01

    The selective removal of cells by ablation is a powerful tool in the study of eukaryotic developmental biology, providing much information about their origin, fate, or function in the developing organism. In Drosophila, three main methods have been used to ablate cells: chemical, genetic, and laser ablation. Each method has its own applicability with regard to developmental stage and the cells to be ablated, and its own limitations. The primary advantage of laser-based ablation is the flexibility provided by the method: The operations can be performed in any cell pattern and at any time in development. Laser-based techniques permit manipulation of structures within cells, even to the molecular level. They can also be used for gene activation. However, laser ablation can be expensive, labor-intensive, and time-consuming. Although live cells can be difficult to image in Drosophila embryos, the use of vital fluorescent imaging methods has made laser-mediated cell manipulation methods more appealing; the methods are relatively straightforward. This article provides the information necessary for setting up and using a laser microscope for lasesr ablation studies.

  10. Glue, steam and Clarivein--Best practice techniques and evidence.

    PubMed

    Whiteley, Mark S

    2015-11-01

    In July 2013, the National Institute of Health and Clinical Excellence (NICE) recommended "endothermal" ablation (meaning endovenous thermal ablation) is the first line treatment for truncal venous reflux in varicose veins. The initial endovenous thermoablation devices were radiofrequency ablation and endovenous laser ablation. More recently, Glue (cyanoacrylate), endovenous steam and Clarivein (mechanochemical ablation or MOCA) have entered the market as new endovenous techniques for the treatment of varicose veins. Glue and Clarivein do not require tumescent anaesthesia and do not use heat and therefore termed non-tumescent non-thermal (NTNT). Steam both requires tumescence and is also a thermal technique (TT). This article reviews the current position of these 3 new technologies in the treatment of varicose veins. © The Author(s) 2015.

  11. Analysis of magnesium and copper in aluminum alloys with high repetition rate laser-ablation spark-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    He, Xiaoyong; Dong, Bo; Chen, Yuqi; Li, Runhua; Wang, Fujuan; Li, Jiaoyang; Cai, Zhigang

    2018-03-01

    In order to improve the analytical speed and performance of laser-ablation based atomic emission spectroscopy, high repetition rate laser-ablation spark-induced breakdown spectroscopy (HRR LA-SIBS) was first developed. Magnesium and copper in aluminum alloys were analyzed with this technique. In the experiments, the fundamental output of an acousto-optically Q-switched Nd:YAG laser operated at 1 kHz repetition rate with low pulse energy and 120 ns pulse width was used to ablate the samples and the plasma emission was enhanced by spark discharge. The spectra were recorded with a compact fiber spectrometer with non-intensified charge-coupled device in non-gating mode. Different parameters relative with analytical performance, such as capacitance, voltage, laser pulse energy were optimized. Under current experimental conditions, calibration curves of magnesium and copper in aluminum alloys were built and limits of detection of them were determined to be 14.0 and 9.9 ppm by HRR LA-SIBS, respectively, which were 8-12 folds better than that achieved by HRR LA under similar experimental condition without spark discharge. The analytical sensitivities are close to those obtained with conventional LIBS but with improved analytical speed as well as possibility of using compact fiber spectrometer. Under high repetition rate operation, the noise level can be decreased and the analytical reproducibility can be improved obviously by averaging multiple measurements within short time. High repetition rate operation of laser-ablation spark-induced breakdown spectroscopy is very helpful for improving analytical speed. It is possible to find applications in fast elements analysis, especially fast two-dimension elemental mapping of solid samples.

  12. Mitomycin-C in corneal surface excimer laser ablation techniques: a report by the American Academy of Ophthalmology.

    PubMed

    Majmudar, Parag A; Schallhorn, Steven C; Cason, John B; Donaldson, Kendall E; Kymionis, George D; Shtein, Roni M; Verity, Steven M; Farjo, Ayad A

    2015-06-01

    To review the published literature assessing the efficacy and safety of mitomycin-C (MMC) as an adjunctive treatment in corneal surface excimer laser ablation procedures. Literature searches of the PubMed and Cochrane Library databases were last conducted on August 19, 2014, without language or date limitations. The searches retrieved a total of 239 references. Of these, members of the Ophthalmic Technology Assessment Committee Refractive Management/Intervention Panel selected 26 articles that were considered to be of high or medium clinical relevance, and the panel methodologist rated each article according to the strength of evidence. Ten studies were rated as level I evidence, 5 studies were rated as level II evidence, and the remaining 11 studies were rated as level III evidence. The majority of the articles surveyed in this report support the role of MMC as an adjunctive treatment in surface ablation procedures. When MMC is applied in the appropriate concentration and confined to the central cornea, the incidence of post-surface ablation haze is decreased. Although a minority of studies that evaluated endothelial cell density (ECD) reported an MMC-related decrease in ECD, no clinical adverse outcomes were reported. Over the past 15 years, the use of MMC during surgery in surface ablation has become widespread. There is good evidence of the effectiveness of MMC when used intraoperatively as prophylaxis against haze in higher myopic ablations. Although there are reports of decreased endothelial counts after the administration of MMC during surgery, the clinical significance of this finding remains uncertain, because no adverse outcomes were reported with as much as 5 years of follow-up. Optimal dosage, effectiveness as prophylaxis in lower myopic and hyperopic ablations, and long-term safety, particularly in eyes with reduced corneal endothelial cell counts from prior intraocular surgery, have yet to be established. Copyright © 2015 American Academy of

  13. Radiofrequency ablation-assisted liver resection: review of the literature and our experience

    PubMed Central

    Yao, Peng

    2006-01-01

    Background: Surgical resection is the best established treatment known to provide long-term survival and possibility of cure for liver malignancy. Intraoperative blood loss has been the major concern during major liver resections, and mortality and morbidity of surgery are clearly associated with the amount of blood loss. Different techniques have been developed to minimize intraoperative blood loss during liver resection. The radiofrequency ablation (RFA) technique has been used widely in the treatment of unresectable liver tumors. This review concentrates on the use of RFA to provide an avascular liver resection plane. Methods and results: The following review is based on two types of RFA device during liver resection: single needle probe RFA and the In-Line RFA device. Conclusion: Liver resection assisted by RFA is safe and is associated with very limited blood loss. PMID:18333135

  14. Low pressure laser ablation coupled to inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Fliegel, Daniel; Günther, Detlef

    2006-07-01

    The particle size distribution in laser ablation inductively coupled plasma mass spectrometry is known to be a critical parameter for complete vaporization of particles. Any strategy to reduce the particle size distribution of laser generated aerosols has the potential to increase the ion signal intensity and to reduce fractionation effects. Due to the fact that vapor generation, nucleation, condensation, and agglomeration take place within an extremely short period of time, ablation under atmospheric pressure might not allow influencing these processes while under reduced pressure condition the cooling of the aerosol and therefore the condensation is expected to be slower. In this study, a low pressure laser ablation cell for the generation of laser aerosols was coupled to an ICP-MS. In contrast to the previously developed trapped ablation mode, the newly designed cell allows the adjustment of the pressure in the ablation cell between 20 and 1400 mbar prior to the ablation. Ablation experiments carried out using this configuration showed a dependence of the aerosol properties (size distribution and particle structure) on the ablation cell pressure. The intensity ratio U/Th measured as a figure of merit for complete vaporization within the ICP indicated a change in the aerosol structure at approximately 500 mbar toward smaller particle size. A significant difference between low pressure and at ambient pressure ablated aerosol was observed. The intensity ratios (U/Th) of the ablated sample moves closer to the bulk composition at lower pressures at the expense of sensitivity. Therefore the decrease in the ICP-MS signal intensity in the low pressure cell can be attributed to vapor deposition within the ablation cell walls. Moreover, scanning electron microscope images of aerosols collected on filters after the low pressure ablation cell suggest the possibility of a slower cooling velocity of the aerosol, which was observed in the condensed material on the surface of

  15. Atrial fibrillation ablation using a closed irrigation radiofrequency ablation catheter.

    PubMed

    Golden, Keith; Mounsey, John Paul; Chung, Eugene; Roomiani, Pahresah; Morse, Michael Andew; Patel, Ankit; Gehi, Anil

    2012-05-01

    Catheter ablation is an effective therapy for symptomatic, medically refractory atrial fibrillation (AF). Open-irrigated radiofrequency (RF) ablation catheters produce transmural lesions at the cost of increased fluid delivery. In vivo models suggest closed-irrigated RF catheters create equivalent lesions, but clinical outcomes are limited. A cohort of 195 sequential patients with symptomatic AF underwent stepwise AF ablation (AFA) using a closed-irrigation ablation catheter. Recurrence of AF was monitored and outcomes were evaluated using Kaplan-Meier survival analysis and Cox proportional hazards models. Mean age was 59.0 years, 74.9% were male, 56.4% of patients were paroxysmal and mean duration of AF was 5.4 years. Patients had multiple comorbidities including hypertension (76.4%), tobacco abuse (42.1%), diabetes (17.4%), and obesity (mean body mass index 30.8). The median follow-up was 55.8 weeks. Overall event-free survival was 73.6% with one ablation and 77.4% after reablation (reablation rate was 8.7%). Median time to recurrence was 26.9 weeks. AF was more likely to recur in patients being treated with antiarrhythmic therapy at the time of last follow-up (recurrence rate 30.3% with antiarrhythmic drugs, 13.2% without antiarrhythmic drugs; hazard ratio [HR] 2.2, 95% confidence interval [CI] 1.1-4.4, P = 0.024) and in those with a history of AF greater than 2 years duration (HR 2.7, 95% CI 1.1-6.9, P = 0.038). Our study represents the largest cohort of patients receiving AFA with closed-irrigation ablation catheters. We demonstrate comparable outcomes to those previously reported in studies of open-irrigation ablation catheters. Given the theoretical benefits of a closed-irrigation system, a large head-to-head comparison using this catheter is warranted. ©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.

  16. Femtosecond ablation of ultrahard materials

    NASA Astrophysics Data System (ADS)

    Dumitru, G.; Romano, V.; Weber, H. P.; Sentis, M.; Marine, W.

    Several ultrahard materials and coatings of definite interest for tribological applications were tested with respect to their response when irradiated with fs laser pulses. Results on cemented tungsten carbide and on titanium carbonitride are reported for the first time and compared with outcomes of investigations on diamond and titanium nitride. The experiments were carried out in air, in a regime of 5-8 J/cm2 fluences, using the beam of a commercial Ti:sapphire laser. The changes induced in the surface morphology were analysed with a Nomarski optical microscope, and with SEM and AFM techniques. From the experimental data and from the calculated incident energy density distributions, the damage and ablation threshold values were determined. As expected, the diamond showed the highest threshold, while the cemented tungsten carbide exhibited typical values for metallic surfaces. The ablation rates determined (under the above-mentioned experimental conditions) were in the range 0.1-0.2 μm per pulse for all the materials investigated.

  17. Noninvasive microwave ablation zone radii estimation using x-ray CT image analysis.

    PubMed

    Weiss, Noam; Goldberg, S Nahum; Nissenbaum, Yitzhak; Sosna, Jacob; Azhari, Haim

    2016-08-01

    The aims of this study were to noninvasively and automatically estimate both the radius of the ablated liver tissue and the radius encircling the treated zone, which also defines where the tissue is definitely untreated during a microwave (MW) thermal ablation procedure. Fourteen ex vivo bovine fresh liver specimens were ablated at 40 W using a 14 G microwave antenna, for durations of 3, 6, 8, and 10 min. The tissues were scanned every 5 s during the ablation using an x-ray CT scanner. In order to estimate the radius of the ablation zone, the acquired images were transformed into a polar presentation by displaying the Hounsfield units (HU) as a function of angle and radius. From this polar presentation, the average HU radial profile was analyzed at each time point and the ablation zone radius was estimated. In addition, textural analysis was applied to the original CT images. The proposed algorithm identified high entropy regions and estimated the treated zone radius per time. The estimated ablated zone radii as a function of treatment durations were compared, by means of correlation coefficient and root mean square error (RMSE) to gross pathology measurements taken immediately post-treatment from similarly ablated tissue. Both the estimated ablation radii and the treated zone radii demonstrated strong correlation with the measured gross pathology values (R(2) ≥ 0.89 and R(2) ≥ 0.86, respectively). The automated ablation radii estimation had an average discrepancy of less than 1 mm (RMSE = 0.65 mm) from the gross pathology measured values, while the treated zone radii showed a slight overestimation of approximately 1.5 mm (RMSE = 1.6 mm). Noninvasive monitoring of MW ablation using x-ray CT and image analysis is feasible. Automatic estimations of the ablation zone radius and the radius encompassing the treated zone that highly correlate with actual ablation measured values can be obtained. This technique can therefore potentially be used to obtain real time

  18. Ultraviolet laser ablation as technique for defect repair of GaN-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Passow, Thorsten; Kunzer, Michael; Pfeuffer, Alexander; Binder, Michael; Wagner, Joachim

    2018-03-01

    Defect repair of GaN-based light-emitting diodes (LEDs) by ultraviolet laser micromachining is reported. Percussion and helical drilling in GaN by laser ablation were investigated using 248 nm nanosecond and 355 nm picosecond pulses. The influence of laser ablation including different laser parameters on electrical and optical properties of GaN-based LED chips was evaluated. The results for LEDs on sapphire with transparent conductive oxide p-type contact on top as well as for thin-film LEDs are reported. A reduction of leakage current by up to six orders in magnitude and homogeneous luminance distribution after proper laser defect treatment were achieved.

  19. Interstitial ablation and imaging of soft tissue using miniaturized ultrasound arrays

    NASA Astrophysics Data System (ADS)

    Makin, Inder R. S.; Gallagher, Laura A.; Mast, T. Douglas; Runk, Megan M.; Faidi, Waseem; Barthe, Peter G.; Slayton, Michael H.

    2004-05-01

    A potential alternative to extracorporeal, noninvasive HIFU therapy is minimally invasive, interstitial ultrasound ablation that can be performed laparoscopically or percutaneously. Research in this area at Guided Therapy Systems and Ethicon Endo-Surgery has included development of miniaturized (~3 mm diameter) linear ultrasound arrays capable of high power for bulk tissue ablation as well as broad bandwidth for imaging. An integrated control system allows therapy planning and automated treatment guided by real-time interstitial B-scan imaging. Image quality, challenging because of limited probe dimensions and channel count, is aided by signal processing techniques that improve image definition and contrast. Simulations of ultrasonic heat deposition, bio-heat transfer, and tissue modification provide understanding and guidance for development of treatment strategies. Results from in vitro and in vivo ablation experiments, together with corresponding simulations, will be described. Using methods of rotational scanning, this approach is shown to be capable of clinically relevant ablation rates and volumes.

  20. Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery

    NASA Astrophysics Data System (ADS)

    Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J. F.

    2014-09-01

    Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuries in the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential use of laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ=2.94 μm), titanium:sapphire femtosecond laser system (λ=1700 nm), and Nd:glass femtosecond laser (λ=1053 nm). Bovine samples were ablated at fluences of 8 to 18 J/cm2 with the erbium:YAG laser, at a power of 300±15 mW with the titanium:sapphire femtosecond system, and at an energy of 3 μJ/pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18 J/cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates.

  1. Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery.

    PubMed

    Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J F

    2014-09-01

    Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuriesin the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential useof laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ = 2.94 μm), titanium:sapphire femtosecond laser system (λ = 1700 nm), and Nd:glass femtosecond laser (λ = 1053 nm). Bovine samples were ablated at fluences of 8 to 18 J∕cm2 with the erbium:YAG laser, at a power of 300 ± 15 mW with the titanium:sapphire femtosecond system, and at an energy of 3 μJ∕pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18 J∕cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates.

  2. Predictive analysis of optical ablation in several dermatological tumoral tissues

    NASA Astrophysics Data System (ADS)

    Fanjul-Vélez, F.; Blanco-Gutiérrez, A.; Salas-García, I.; Ortega-Quijano, N.; Arce-Diego, J. L.

    2013-06-01

    Optical techniques for treatment and characterization of biological tissues are revolutionizing several branches of medical praxis, for example in ophthalmology or dermatology. The non-invasive, non-contact and non-ionizing character of optical radiation makes it specially suitable for these applications. Optical radiation can be employed in medical ablation applications, either for tissue resection or surgery. Optical ablation may provide a controlled and clean cut on a biological tissue. This is particularly relevant in tumoral tissue resection, where a small amount of cancerous cells could make the tumor appear again. A very important aspect of tissue optical ablation is then the estimation of the affected volume. In this work we propose a complete predictive model of tissue ablation that provides an estimation of the resected volume. The model is based on a Monte Carlo approach for the optical propagation of radiation inside the tissue, and a blow-off model for tissue ablation. This model is applied to several types of dermatological tumoral tissues, specifically squamous cells, basocellular and infiltrative carcinomas. The parameters of the optical source are varied and the estimated resected volume is calculated. The results for the different tumor types are presented and compared. This model can be used for surgical planning, in order to assure the complete resection of the tumoral tissue.

  3. THE USE OF THE LIGASURE™ DEVICE FOR SCROTAL ABLATION IN MARSUPIALS.

    PubMed

    Cusack, Lara; Cutler, Daniel; Mayer, Joerg

    2017-03-01

    Five sugar gliders ( Petaurus breviceps ), ranging in age from 3 mo to 3.5 yr of age, and one opossum ( Didelphis virginianus ), age 4.5 mo, presented for elective orchiectomy and scrotal ablation. The LigaSure™ device was safely used for orchiectomy and scrotal ablation in both species. Surgical time with the LigaSure was approximately 4 sec. No grooming of the incision site or self-mutilation was seen in the first 72 hr postoperatively. One sugar glider required postoperative wound care approximately 10 days postoperatively following incision-site grooming by a conspecific. The LigaSure provides a rapid, technologically simple and safe surgical technique for scrotal ablation and orchiectomy in the marsupial patient that minimizes surgical, anesthetic, and recovery times.

  4. A comparison of hydro-instabilities in CH, HDC, and beryllium ablators on NIF

    NASA Astrophysics Data System (ADS)

    Smalyuk, V. A.; Robey, H. F.; Ali, S.; Berzak Hopkins, L. F.; Casey, D. T.; Celliers, P. M.; Clark, D. S.; Felker, S. J.; Field, J. E.; Haan, S. W.; Hammel, B. A.; Hsing, W. W.; Kroll, J. J.; Landen, O. L.; Lepape, S.; Macphee, A. G.; Martinez, D.; Milovich, J.; Nikroo, A.; Pickworth, L.; Stadermann, M.; Weber, C. R.; Kline, J.; Loomis, E.; Yi, A.

    2017-10-01

    A comparison of the hydrodynamic growth in plastic, high-density carbon, and beryllium ablators will be presented in indirect-drive implosions on National Ignition Facility. This comparison is based on experimentally measured instabilities in all phases of implosions for the three ablators. The 2-D and 3-D perturbations were measured at the ablation-surface with the Hydrodynamic Growth Radiography platform. In the deceleration phase of implosions, innovative self-emission and ``self-backlight'' techniques were used. Results of the 3-D perturbation growth including engineering features will also be presented for convergence up to 20 and compared for the three ablators. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  5. Microwave thermal ablation of spinal metastatic bone tumors.

    PubMed

    Kastler, Adrian; Alnassan, Hussein; Aubry, Sébastien; Kastler, Bruno

    2014-09-01

    To assess feasibility, safety, and efficacy of microwave ablation of spinal metastatic bone tumors. Retrospective study of 17 patients with 20 spinal metastatic tumors treated with microwave ablation under computed tomographic guidance between March 2011 and August 2013 was performed. Ablations were performed under local anesthesia and nitrous oxide ventilation. Lesions were lumbar (n = 10), sacral (n = 7), and thoracic (n = 3) in location. Primary neoplastic sites were lung (n = 9), prostate (n = 4), kidney (n = 6), and uterus (n = 1). Adjunct cementoplasty was performed in nine cases, and a temperature-monitoring device was used in four cases. Procedure effectiveness was evaluated by visual analog scale (VAS) during a 6-month follow-up. Patient medical records were reviewed, and demographic and clinical data, tumor characteristics, and information on pain were assessed. Mean ablation time was 4.4 minutes ± 2.7 (range, 1-8 min), with an average of 3.8 cycles per ablation at 60 W (range, 30-70 W). The preprocedure mean VAS score was 7.4 ± 1.2 (range, 6-9). Pain relief was achieved in all but one patient. Follow-up VAS scores were as follows: day 0, 1.3 ± 1.8 (P < .001); day 7, 1.6 ± 1.7 (P < .001); month 1, 1.9 ± 1.6 (P < .001); month 3, 2.2 ± 1.5 (P < .001); and month 6, 2.3 ± 1.4 (P < .01). No complications were noted. Microwave ablation appears to be feasible, safe, and an effective treatment of painful refractory spinal metastases and may be considered as a potential alternative percutaneous technique in the management of spinal metastases. Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.

  6. Image-Guided Ablation of Adrenal Lesions

    PubMed Central

    Yamakado, Koichiro

    2014-01-01

    Although laparoscopic adrenalectomy has remained the standard of care for the treatment for adrenal tumors, percutaneous image-guided ablation therapy, such as chemical ablation, radiofrequency ablation, cryoablation, and microwave ablation, has been shown to be clinically useful in many nonsurgical candidates. Ablation therapy has been used to treat both functioning adenomas and malignant tumors, including primary adrenal carcinoma and metastasis. For patients with functioning adenomas, biochemical and symptomatic improvement is achieved in 96 to 100% after ablation; for patients with malignant adrenal neoplasms, however, the survival benefit from ablation therapy remains unclear, though good initial results have been reported. This article outlines the current role of ablation therapy for adrenal lesions, as well as identifying some of the technical considerations for this procedure. PMID:25049444

  7. OCDR guided laser ablation device

    DOEpatents

    Dasilva, Luiz B.; Colston, Jr., Bill W.; James, Dale L.

    2002-01-01

    A guided laser ablation device. The device includes a mulitmode laser ablation fiber that is surrounded by one or more single mode optical fibers that are used to image in the vicinity of the laser ablation area to prevent tissue damage. The laser ablation device is combined with an optical coherence domain reflectometry (OCDR) unit and with a control unit which initializes the OCDR unit and a high power laser of the ablation device. Data from the OCDR unit is analyzed by the control unit and used to control the high power laser. The OCDR images up to about 3 mm ahead of the ablation surface to enable a user to see sensitive tissue such as a nerve or artery before damaging it by the laser.

  8. Controlled tuning of thin film deposition of IrO{sub 2} on Si using pulsed laser ablation technique

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koshy, Abraham M., E-mail: abraham@ug.iisc.in; Bhat, Shwetha G., E-mail: shwethabhat@physics.iisc.ernet.in; Kumar, P. S. Anil, E-mail: anil@physics.iisc.ernet.in

    2016-05-06

    We have successfully grown a stable phase of polycrystalline IrO{sub 2} on Si (100) substrate. We have found that the phase of IrO{sub 2} can be controllably tuned to obtain either Ir or IrO{sub 2} using pulsed laser ablation technique. O{sub 2} conditions during the deposition influences the phase directly and drastically whereas annealing conditions do not show any variation in the phase of thin film. X-ray diffraction and X-ray photoemission experiments confirm both Ir and IrO{sub 2} can be successively grown on Si using IrO{sub 2} target. Also, the morphology is found to be influenced by the O{sub 2}more » conditions.« less

  9. Radiofrequency ablation for benign thyroid nodules.

    PubMed

    Bernardi, S; Stacul, F; Zecchin, M; Dobrinja, C; Zanconati, F; Fabris, B

    2016-09-01

    Benign thyroid nodules are an extremely common occurrence. Radiofrequency ablation (RFA) is gaining ground as an effective technique for their treatment, in case they become symptomatic. Here we review what are the current indications to RFA, its outcomes in terms of efficacy, tolerability, and cost, and also how it compares to the other conventional and experimental treatment modalities for benign thyroid nodules. Moreover, we will also address the issue of treating with this technique patients with cardiac pacemakers (PM) or implantable cardioverter-defibrillators (ICD), as it is a rather frequent occurrence that has never been addressed in detail in the literature.

  10. Ablation of steel by microsecond pulse trains

    NASA Astrophysics Data System (ADS)

    Windeler, Matthew Karl Ross

    Laser micromachining is an important material processing technique used in industry and medicine to produce parts with high precision. Control of the material removal process is imperative to obtain the desired part with minimal thermal damage to the surrounding material. Longer pulsed lasers, with pulse durations of milli- and microseconds, are used primarily for laser through-cutting and welding. In this work, a two-pulse sequence using microsecond pulse durations is demonstrated to achieve consistent material removal during percussion drilling when the delay between the pulses is properly defined. The light-matter interaction moves from a regime of surface morphology changes to melt and vapour ejection. Inline coherent imaging (ICI), a broadband, spatially-coherent imaging technique, is used to monitor the ablation process. The pulse parameter space is explored and the key regimes are determined. Material removal is observed when the pulse delay is on the order of the pulse duration. ICI is also used to directly observe the ablation process. Melt dynamics are characterized by monitoring surface changes during and after laser processing at several positions in and around the interaction region. Ablation is enhanced when the melt has time to flow back into the hole before the interaction with the second pulse begins. A phenomenological model is developed to understand the relationship between material removal and pulse delay. Based on melt refilling the interaction region, described by logistic growth, and heat loss, described by exponential decay, the model is fit to several datasets. The fit parameters reflect the pulse energies and durations used in the ablation experiments. For pulse durations of 50 us with pulse energies of 7.32 mJ +/- 0.09 mJ, the logisitic growth component of the model reaches half maximum after 8.3 mus +/- 1.1 us and the exponential decays with a rate of 64 mus +/- 15 us. The phenomenological model offers an interpretation of the material

  11. Remote magnetic navigation for circumferential pulmonary vein ablation: single-catheter technique or additional use of a circular mapping catheter?

    PubMed

    Vollmann, Dirk; Lüthje, Lars; Seegers, Joachim; Sohns, Christian; Sossalla, Samuel; Sohns, Jan; Röver, Christian; Hasenfuß, Gerd; Zabel, Markus

    2014-10-01

    Remote magnetic navigation (RMN) is utilized for catheter guidance during pulmonary vein ablation (PVA). We aimed to determine whether the additional use of a circular mapping catheter (CMC) influences efficacy and outcome of RMN-guided PVA. A total of 80 consecutive subjects (65 % male, age 62 ± 9 years) underwent circumferential PVA with a 3D mapping system and an RMN-guided irrigated catheter. Procedural endpoint was complete PV isolation (PVI), total radiofrequency (RF) time >60 min, or procedure duration >5 h. PVI was defined as an entrance and/or exit block, diagnosed with a CMC within the PV ostium or by pacing via the roving RMN-guided catheter (single-catheter technique). Prolonged Holter monitoring after 3 and 6 months was used to detect atrial tachyarrhythmia (AT/AF) recurrences. Complete PVI was achieved in 56 % (45/80) of all subjects (isolated PVs per patient, 3.1 ± 1.2; RF time, 56.3 ± 17.2 min; procedure duration, 3.8 ± 0.8 h). Prospective validation of the single-catheter technique for diagnosing PVI demonstrated high concordance (94 %) with blinded CMC results. CMC use in first-time PVA was associated with similar total RF and procedure times but higher PV isolation rate. Upon multivariate analysis, CMC use, female gender, left PV, smaller PV ostium and repeat PVA predicted PVI during RMN-guided ablation. Persistent AF and mitral regurgitation at baseline and the number of non-isolated PVs predicted AT/AF recurrence during follow-up. Concomitant CMC use for first-time, RMN-guided PVA is associated with similar procedure duration but higher PV isolation rates as compared to a single-catheter approach. Since the number of isolated PVs predicts freedom from AT/AF, CMC utilization appears advisable for first-time, RMN-guided PVA.

  12. MR-guided high-intensity focused ultrasound ablation of breast cancer with a dedicated breast platform.

    PubMed

    Merckel, Laura G; Bartels, Lambertus W; Köhler, Max O; van den Bongard, H J G Desirée; Deckers, Roel; Mali, Willem P Th M; Binkert, Christoph A; Moonen, Chrit T; Gilhuijs, Kenneth G A; van den Bosch, Maurice A A J

    2013-04-01

    Optimizing the treatment of breast cancer remains a major topic of interest. In current clinical practice, breast-conserving therapy is the standard of care for patients with localized breast cancer. Technological developments have fueled interest in less invasive breast cancer treatment. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a completely noninvasive ablation technique. Focused beams of ultrasound are used for ablation of the target lesion without disrupting the skin and subcutaneous tissues in the beam path. MRI is an excellent imaging method for tumor targeting, treatment monitoring, and evaluation of treatment results. The combination of HIFU and MR imaging offers an opportunity for image-guided ablation of breast cancer. Previous studies of MR-HIFU in breast cancer patients reported a limited efficacy, which hampered the clinical translation of this technique. These prior studies were performed without an MR-HIFU system specifically developed for breast cancer treatment. In this article, a novel and dedicated MR-HIFU breast platform is presented. This system has been designed for safe and effective MR-HIFU ablation of breast cancer. Furthermore, both clinical and technical challenges are discussed, which have to be solved before MR-HIFU ablation of breast cancer can be implemented in routine clinical practice.

  13. New methods to detect particle velocity and mass flux in arc-heated ablation/erosion facilities

    NASA Technical Reports Server (NTRS)

    Brayton, D. B.; Bomar, B. W.; Seibel, B. L.; Elrod, P. D.

    1980-01-01

    Arc-heated flow facilities with injected particles are used to simulate the erosive and ablative/erosive environments encountered by spacecraft re-entry through fog, clouds, thermo-nuclear explosions, etc. Two newly developed particle diagnostic techniques used to calibrate these facilities are discussed. One technique measures particle velocity and is based on the detection of thermal radiation and/or chemiluminescence from the hot seed particles in a model ablation/erosion facility. The second technique measures a local particle rate, which is proportional to local particle mass flux, in a dust erosion facility by photodetecting and counting the interruptions of a focused laser beam by individual particles.

  14. Surgical Ablation Assay for Studying Eye Regeneration in Planarians.

    PubMed

    Morton, Jacob M; Saad, Marwa A; Beane, Wendy S

    2017-04-14

    In the study of adult stem cells and regenerative mechanisms, planarian flatworms are a staple in vivo model system. This is due in large part to their abundant pluripotent stem cell population and ability to regenerate all cell and tissue types after injuries that would be catastrophic for most animals. Recently, planarians have gained popularity as a model for eye regeneration. Their ability to regenerate the entire eye (comprised of two tissue types: pigment cells and photoreceptors) allows for the dissection of the mechanisms regulating visual system regeneration. Eye ablation has several advantages over other techniques (such as decapitation or hole punch) for examining eye-specific pathways and mechanisms, the most important of which is that regeneration is largely restricted to eye tissues alone. The purpose of this video article is to demonstrate how to reliably remove the planarian optic cup without disturbing the brain or surrounding tissues. The handling of worms and maintenance of an established colony is also described. This technique uses a 31 G, 5/16-inch insulin needle to surgically scoop out the optic cup of planarians immobilized on a cold plate. This method encompasses both single and double eye ablation, with eyes regenerating within 1-2 weeks, allowing for a wide range of applications. In particular, this ablation technique can be easily combined with pharmacological and genetic (RNA interference) screens for a better understanding of regenerative mechanisms and their evolution, eye stem cells and their maintenance, and phototaxic behavioral responses and their neurological basis.

  15. Benign thyroid nodules treatment using percutaneous laser ablation (PLA) and radiofrequency ablation (RFA).

    PubMed

    Mauri, Giovanni; Cova, Luca; Monaco, Cristian Giuseppe; Sconfienza, Luca Maria; Corbetta, Sabrina; Benedini, Stefano; Ambrogi, Federico; Milani, Valentina; Baroli, Alberto; Ierace, Tiziana; Solbiati, Luigi

    2016-11-15

    To evaluate the reduction over time of benign thyroid nodules treated using percutaneous laser ablation (PLA) and radiofrequency ablation (RFA) by the same equipe. Ninety patients (age 55.6 ± 14.1 years) underwent ablation for benign thyroid nodule causing compression/aesthetic dissatisfaction from 2011. Fifty-nine (age 55.8 ± 14.1 years) underwent RFA and 31 (age 55.2 ± 14.2 years) PLA, ultrasound guided. Technical success, complications, duration of ablation and treatment, energy deployed, volumetric percentage reduction at 1, 6 and 12 months were derived. A regression model for longitudinal measurements was used with random intercept and random slope. Values are expressed as mean ± standard deviation or N (%). Technical success was always obtained. No major complications occurred. Mean ablation time was 30.1 ± 13.8 vs. 13.9 ± 5.9 min (p < .0001) and mean energy deployment was 5422.3 ± 2484.5 J vs. 34 662.7 ± 15 812.3 J in PLA vs. RFA group. Mean volume reduced from 20.3 ± 16.4 ml to 13.17 ± 10.74 ml (42% ± 17% reduction) at 1st month, 8.7 ± 7.4 ml (60% ± 15% reduction) at 6th month and 7.1 ± 7.7 ml (70%% ± 16% reduction) at 12th month, in PLA group, and from 32.7 ± 19.5 ml to 17.2 ± 12.9 ml (51%±15% reduction) at 1st month, 12.8 ± 9.6 ml (64 ± 14% reduction) at 6th month and 9.9 ± 9.2 ml (74% ± 14% reduction) at 12th month in RFA group. No difference in time course of the relative volume reduction between the two techniques was found. RFA and PLA are similarly feasible, safe and effective in treating benign thyroid nodules when performed by the same equipe. RFA is faster than PLA but require significantly higher energy.

  16. Time-resolved Measurements of ICF Capsule Ablator Properties by Streaked X-Ray Radiography

    NASA Astrophysics Data System (ADS)

    Hicks, Damien

    2008-11-01

    Determining the capsule ablator thickness and peak laser or x-ray drive pressure required to optimize fuel compression is a critical part of ensuring ICF ignition on the NIF. If too little ablator is burned off, the implosion velocity will be too low for adequate final compression; if too much ablator is burned off, the fuel will be preheated or the shell will be broken up by growth of hydrodynamic instabilities, again compromising compression. Avoiding such failure modes requires having an accurate, in-flight measure of the implosion velocity, areal density, and remaining mass of the ablator near peak velocity. We present a new technique which achieves simultaneous time-resolved measurements of all these parameters in a single, area-backlit, x-ray streaked radiograph. This is accomplished by tomographic inversion of the radiograph to determine the radial density profile at each time step; scalar quantities such as the average position, areal density, and mass of the ablator can then be calculated by taking moments of this density profile. Details of the successful demonstration of this technique using backlit Cu-doped Be capsule implosions at the Omega facility will be presented. This work was performed under the auspices of the U.S.Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and in collaboration with Brian Spears, David Braun, Peter Celliers, Gilbert Collins, and Otto Landen at LLNL and Rick Olson at SNL.

  17. Robotic navigation and ablation.

    PubMed

    Malcolme-Lawes, L; Kanagaratnam, P

    2010-12-01

    Robotic technologies have been developed to allow optimal catheter stability and reproducible catheter movements with the aim of achieving contiguous and transmural lesion delivery. Two systems for remote navigation of catheters within the heart have been developed; the first is based on a magnetic navigation system (MNS) Niobe, Stereotaxis, Saint-Louis, Missouri, USA, the second is based on a steerable sheath system (Sensei, Hansen Medical, Mountain View, CA, USA). Both robotic and magnetic navigation systems have proven to be feasible for performing ablation of both simple and complex arrhythmias, particularly atrial fibrillation. Studies to date have shown similar success rates for AF ablation compared to that of manual ablation, with many groups finding a reduction in fluoroscopy times. However, the early learning curve of cases demonstrated longer procedure times, mainly due to additional setup times. With centres performing increasing numbers of robotic ablations and the introduction of a pressure monitoring system, lower power settings and instinctive driving software, complication rates are reducing, and fluoroscopy times have been lower than manual ablation in many studies. As the demand for catheter ablation for arrhythmias such as atrial fibrillation increases and the number of centres performing these ablations increases, the demand for systems which reduce the hand skill requirement and improve the comfort of the operator will also increase.

  18. Cubic spline numerical solution of an ablation problem with convective backface cooling

    NASA Astrophysics Data System (ADS)

    Lin, S.; Wang, P.; Kahawita, R.

    1984-08-01

    An implicit numerical technique using cubic splines is presented for solving an ablation problem on a thin wall with convective cooling. A non-uniform computational mesh with 6 grid points has been used for the numerical integration. The method has been found to be computationally efficient, providing for the care under consideration of an overall error of about 1 percent. The results obtained indicate that the convective cooling is an important factor in reducing the ablation thickness.

  19. Transarterial Chemoembolization Combined with Either Radiofrequency or Microwave Ablation in Management of Hepatocellular Carcinoma

    PubMed Central

    Abdelaziz, Ashraf Omar; Abdelmaksoud, Ahmed Hosni; Nabeel, Mohamed Mahmoud; Shousha, Hend Ibrahim; Cordie, Ahmed Abdelmonem; Mahmoud, Sherif Hamdy; Medhat, Eman; Omran, Dalia; Elbaz, Tamer Mahmoud

    2017-01-01

    Introduction: Local ablative therapy and trans arterial chemoembolization (TACE) are applied to ablate non resectable hepatocellular carcinoma (HCC). Combination of both techniques has proven to be more effective. We aimed to study combined ablation techniques and assess survival benefit comparing TACE with radiofrequency (RFA) versus TACE with microwave (MWA) techniques. Methods: We retrospectively studied 22 patients who were ablated using TACE-RFA and 45 with TACE-MWA. All were classified as Child A-B and lesions did not exceed 5 cm in diameter. TACE was followed within two weeks by either RFA or MWA. We recorded total and partial ablation rates and complication rates. Survival analysis was then performed. Results: TACE-MWA showed a higher tendency to provide complete response rates than TACE-RFA (P 0.06). This was particularly evident with lesions sized 3-5 cm (P 0.01). Rates of complications showed no significant difference between the groups. Overall median survival was 27 months. The overall actuarial probability of survival was 80.1% at 1 year, 55% at 2 years, and 36.3% at 3 years. The recurrence free survival at 1 year, 2years and 3 years for the TACE-RFA group was 70%, 42% and 14% respectively and for TACE-MWA group 81.2%, 65.1% and 65.1% without any significant difference (P 0.1). In relation to the size of focal lesions, no statistically significant difference in the survival rates was detected between the groups. Conclusion: TACE-MWA led to better response rates than TACE-RFA with tumors 3-5 cm, with no difference in survival rates. PMID:28240516

  20. Transarterial Chemoembolization Combined with Either Radiofrequency or Microwave Ablation in Management of Hepatocellular Carcinoma

    PubMed

    Abdelaziz, Ashraf Omar; Abdelmaksoud, Ahmed Hosni; Nabeel, Mohamed Mahmoud; Shousha, Hend Ibrahim; Cordie, Ahmed Abdelmonem; Mahmoud, Sherif Hamdy; Medhat, Eman; Omran, Dalia; Elbaz, Tamer Mahmoud

    2017-01-01

    Introduction: Local ablative therapy and trans arterial chemoembolization (TACE) are applied to ablate non resectable hepatocellular carcinoma (HCC). Combination of both techniques has proven to be more effective. We aimed to study combined ablation techniques and assess survival benefit comparing TACE with radiofrequency (RFA) versus TACE with microwave (MWA) techniques. Methods: We retrospectively studied 22 patients who were ablated using TACE-RFA and 45 with TACE-MWA. All were classified as Child A-B and lesions did not exceed 5 cm in diameter. TACE was followed within two weeks by either RFA or MWA. We recorded total and partial ablation rates and complication rates. Survival analysis was then performed. Results: TACE-MWA showed a higher tendency to provide complete response rates than TACE-RFA (P 0.06). This was particularly evident with lesions sized 3-5 cm (P 0.01). Rates of complications showed no significant difference between the groups. Overall median survival was 27 months. The overall actuarial probability of survival was 80.1% at 1 year, 55% at 2 years, and 36.3% at 3 years. The recurrence free survival at 1 year, 2years and 3 years for the TACE-RFA group was 70%, 42% and 14% respectively and for TACE-MWA group 81.2%, 65.1% and 65.1% without any significant difference (P 0.1). In relation to the size of focal lesions, no statistically significant difference in the survival rates was detected between the groups. Conclusion: TACE-MWA led to better response rates than TACE-RFA with tumors 3-5 cm, with no difference in survival rates. Creative Commons Attribution License

  1. Experimental setup for the laboratory investigation of micrometeoroid ablation using a dust accelerator.

    PubMed

    Thomas, Evan; Simolka, Jonas; DeLuca, Michael; Horányi, Mihály; Janches, Diego; Marshall, Robert A; Munsat, Tobin; Plane, John M C; Sternovsky, Zoltan

    2017-03-01

    A facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to generate iron particles with velocities of 10-70 km/s. The particles are then introduced into a chamber pressurized with a target gas, where the pressure is adjustable between 0.01 and 0.5 Torr, and the particle partially or completely ablates over a short distance. An array of biased electrodes above and below the ablation path is used to collect the generated ions/electrons with a spatial resolution of 2.6 cm along the ablating particles' path, thus allowing the study of the spatiotemporal evolution of the process. For completely ablated particles, the total collected charge directly yields the ionization coefficient of a given dust material-target gas combination. The first results of this facility measured the ionization coefficient of iron atoms with N 2 , air, CO 2 , and He target gases for impact velocities >20 km/s, and are reported by Thomas et al. [Geophys. Res. Lett. 43, 3645 (2016)]. The ablation chamber is also equipped with four optical ports that allow for the detection of the light emitted by the ablating particle. A multichannel photomultiplier tube system is used to observe the ablation process with a spatial and temporal resolution of 0.64 cm and 90 ns. The preliminary results indicate that it is possible to calculate the velocity of the ablating particle from the optical observations, and in conjunction with the spatially resolved charge measurements allow for experimental validation of ablation models in future studies.

  2. Experimental setup for the laboratory investigation of micrometeoroid ablation using a dust accelerator

    NASA Astrophysics Data System (ADS)

    Thomas, Evan; Simolka, Jonas; DeLuca, Michael; Horányi, Mihály; Janches, Diego; Marshall, Robert A.; Munsat, Tobin; Plane, John M. C.; Sternovsky, Zoltan

    2017-03-01

    A facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to generate iron particles with velocities of 10-70 km/s. The particles are then introduced into a chamber pressurized with a target gas, where the pressure is adjustable between 0.01 and 0.5 Torr, and the particle partially or completely ablates over a short distance. An array of biased electrodes above and below the ablation path is used to collect the generated ions/electrons with a spatial resolution of 2.6 cm along the ablating particles' path, thus allowing the study of the spatiotemporal evolution of the process. For completely ablated particles, the total collected charge directly yields the ionization coefficient of a given dust material-target gas combination. The first results of this facility measured the ionization coefficient of iron atoms with N2, air, CO2, and He target gases for impact velocities >20 km/s, and are reported by Thomas et al. [Geophys. Res. Lett. 43, 3645 (2016)]. The ablation chamber is also equipped with four optical ports that allow for the detection of the light emitted by the ablating particle. A multichannel photomultiplier tube system is used to observe the ablation process with a spatial and temporal resolution of 0.64 cm and 90 ns. The preliminary results indicate that it is possible to calculate the velocity of the ablating particle from the optical observations, and in conjunction with the spatially resolved charge measurements allow for experimental validation of ablation models in future studies.

  3. Experimental Setup for the Laboratory Investigation of Micrometeoroid Ablation Using a Dust Accelerator

    NASA Technical Reports Server (NTRS)

    Thomas, Evan; Simolka, Jonas; DeLuca, Michael; Horanyi, Mihaly; Janches, Diego; Marshall, Robert A.; Munsat, Tobin; Plane, John M. C.; Sternovsky, Zoltan

    2017-01-01

    A facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to generate iron particles with velocities of 10-70 kilometers. The particles are then introduced into a chamber pressurized with a target gas, where the pressure is adjustable between 0.01 and 0.5 Torr, and the particle partially or completely ablates over a short distance. An array of biased electrodes above and below the ablation path is used to collect the generated ions/electrons with a spatial resolution of 2.6 centimeters along the ablating particles path, thus allowing the study of the spatiotemporal evolution of the process. For completely ablated particles, the total collected charge directly yields the ionization coefficient of a given dust material-target gas combination. The first results of this facility measured the ionization coefficient of iron atoms with N2, air, CO2, and He target gases for impact velocities greater than 20 kilometers per second, and are reported by Thomas et al. The ablation chamber is also equipped with four optical ports that allow for the detection of the light emitted by the ablating particle. A multichannel photomultiplier tube system is used to observe the ablation process with a spatial and temporal resolution of 0.64 centimeters and 90 nanoseconds. The preliminary results indicate that it is possible to calculate the velocity of the ablating particle from the optical observations, and in conjunction with the spatially resolved charge measurements allow for experimental validation of ablation models in future studies.

  4. Differentiation of pre-ablation and post-ablation late gadolinium-enhanced cardiac MRI scans of longstanding persistent atrial fibrillation patients

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Zhuang, Xiahai; Khan, Habib; Haldar, Shouvik; Nyktari, Eva; Li, Lei; Ye, Xujiong; Slabaugh, Greg; Wong, Tom; Mohiaddin, Raad; Keegan, Jennifer; Firmin, David

    2017-03-01

    Late Gadolinium-Enhanced Cardiac MRI (LGE CMRI) is an emerging non-invasive technique to image and quantify preablation native and post-ablation atrial scarring. Previous studies have reported that enhanced image intensities of the atrial scarring in the LGE CMRI inversely correlate with the left atrial endocardial voltage invasively obtained by electro-anatomical mapping. However, the reported reproducibility of using LGE CMRI to identify and quantify atrial scarring is variable. This may be due to two reasons: first, delineation of the left atrium (LA) and pulmonary veins (PVs) anatomy generally relies on manual operation that is highly subjective, and this could substantially affect the subsequent atrial scarring segmentation; second, simple intensity based image features may not be good enough to detect subtle changes in atrial scarring. In this study, we hypothesized that texture analysis can provide reliable image features for the LGE CMRI images subject to accurate and objective delineation of the heart anatomy based on a fully-automated whole heart segmentation (WHS) method. We tested the extracted texture features to differentiate between pre-ablation and post-ablation LGE CMRI studies in longstanding persistent atrial fibrillation patients. These patients often have extensive native scarring and differentiation from post-ablation scarring can be difficult. Quantification results showed that our method is capable of solving this classification task, and we can envisage further deployment of this texture analysis based method for other clinical problems using LGE CMRI.

  5. Siderophile Element Profile Measurements in Iron Meteorites Using Laser Ablation ICP-MS

    NASA Technical Reports Server (NTRS)

    Watson, H. C.; Watson, E. B.; McDonough, W. F.

    2005-01-01

    Understanding the behaviour of siderophile elements during cooling of iron meteorites can lead to insight into the general thermal histories of the meteorites as well as their respective parent bodies. Traditionally trace element analyses in meteorites have been done using techniques that only measure the average concentration in each phase. With these methods, all of the spatial information with respect to the distribution of an element within one phase is lost. Measuring concentration profiles of trace elements in meteorites is now possible, with the advent of high-resolution analytical techniques such as laser ablation, inductively coupled plasma mass spectrometry (LA-ICP-MS) with spatial resolution <20 microns. [e.g. 1,2] and secondary ion mass spectrometry [3]. These profiles can give more insight into both the partitioning and diffusive behavior of siderophile elements in metal systems relevant to iron meteorites, as well as parent body cooling rates.

  6. Relationship between LIBS Ablation and Pit Volume for Geologic Samples: Applications for in situ Absolute Geochronology

    NASA Technical Reports Server (NTRS)

    Devismes, D.; Cohen, Barbara A.

    2014-01-01

    In planetary sciences, in situ absolute geochronology is a scientific and engineering challenge. Currently, the age of the Martian surface can only be determined by crater density counting. However this method has significant uncertainties and needs to be calibrated with absolute ages. We are developing an instrument to acquire in situ absolute geochronology based on the K-Ar method. The protocol is based on the laser ablation of a rock by hundreds of laser pulses. Laser Induced Breakdown Spectroscopy (LIBS) gives the potassium content of the ablated material and a mass spectrometer (quadrupole or ion trap) measures the quantity of 40Ar released. In order to accurately measure the quantity of released 40Ar in cases where Ar is an atmospheric constituent (e.g., Mars), the sample is first put into a chamber under high vacuum. The 40Arquantity, the concentration of K and the estimation of the ablated mass are the parameters needed to give the age of the rocks. The main uncertainties with this method are directly linked to the measures of the mass (typically some µg) and of the concentration of K by LIBS (up to 10%). Because the ablated mass is small compared to the mass of the sample, and because material is redeposited onto the sample after ablation, it is not possible to directly measure the ablated mass. Our current protocol measures the ablated volume and estimates the sample density to calculate ablated mass. The precision and accuracy of this method may be improved by using knowledge of the sample's geologic properties to predict its response to laser ablation, i.e., understanding whether natural samples have a predictable relationship between laser energy deposited and resultant ablation volume. In contrast to most previous studies of laser ablation, theoretical equations are not highly applicable. The reasons are numerous, but the most important are: a) geologic rocks are complex, polymineralic materials; b) the conditions of ablation are unusual (for example

  7. Percutaneous intrapericardial echocardiography during catheter ablation: a feasibility study.

    PubMed

    Horowitz, Barbara Natterson; Vaseghi, Marmar; Mahajan, Aman; Cesario, David A; Buch, Eric; Valderrábano, Miguel; Boyle, Noel G; Ellenbogen, Kenneth A; Shivkumar, Kalyanam

    2006-11-01

    Percutaneous pericardial access, epicardial mapping, and ablation have been used successfully for catheter ablation procedures. The purpose of this study was to evaluate the safety and feasibility of closed-chest direct epicardial ultrasound imaging for aiding cardiac catheter ablation procedures. An intracardiac ultrasound catheter was used for closed-chest epicardial imaging of the heart in 10 patients undergoing percutaneous epicardial access for catheter ablation. All patients underwent concomitant intracardiac echocardiography and preprocedural transesophageal echocardiography. Using a double-wire technique, two sheaths were placed in the pericardium, and a phased-array ultrasound catheter was manipulated within the pericardial sinuses for imaging. Multiple images from varying angles were obtained for catheter navigation. Notably, image stability was excellent, and structures such as the left atrial appendage were seen in great detail. No complications resulting from use of the ultrasound catheter in the pericardium occurred, and no restriction of movement due to the presence of the additional catheter in the pericardial space was observed. Wall motion was correlated to voltage maps in five patients and showed that areas of scars correlated with wall-motion abnormalities. Normal wall-motion score correlated to sensed signals of 4.2 +/- 0.3 mV (normal myocardium >1.5 mV), and scores >1 correlated to areas with signals <0.5 mV in that territory). Intrapericardial imaging using an ultrasound catheter is feasible and safe and has the potential to provide additional valuable information for complex ablation procedures.

  8. Effect of absorbing coating on ablation of diamond by IR laser pulses

    NASA Astrophysics Data System (ADS)

    Kononenko, T. V.; Pivovarov, P. A.; Khomich, A. A.; Khmel'nitskii, R. A.; Konov, V. I.

    2018-03-01

    We study the possibility of increasing the efficiency and quality of laser ablation microprocessing of diamond by preliminary forming an absorbing layer on its surface. The laser pulses having a duration of 1 ps and 10 ns at a wavelength of 1030 nm irradiate the polycrystalline diamond surface coated by a thin layer of titanium or graphite. We analyse the dynamics of the growth of the crater depth as a function of the number of pulses and the change in optical transmission of the ablated surface. It is found that under irradiation by picosecond pulses the preliminary graphitisation allows one to avoid the laser-induced damage of the internal diamond volume until the appearance of a self-maintained graphitised layer. The absorbing coating (both graphite and titanium) much stronger affects ablation by nanosecond pulses, since it reduces the ablation threshold by more than an order of magnitude and allows full elimination of a laser-induced damage of deep regions of diamond and uncontrolled explosive ablation in the nearsurface layer.

  9. Ablative and transport fractionation of trace elements during laser sampling of glass and copper

    NASA Astrophysics Data System (ADS)

    Outridge, P. M.; Doherty, W.; Gregoire, D. C.

    1997-12-01

    The fractionation of trace elements due to ablation and transport processes was quantified during Q-switched infrared laser sampling of glass and copper reference materials. Filter-trapping of the ablated product at different points in the sample introduction system showed ablation and transport sometimes caused opposing fractionation effects, leading to a confounded measure of overall (ablative + transport) fractionation. An unexpected result was the greater ablative fractionation of some elements (Au, Ag, Bi, Te in glass and Au, Be, Bi, Ni, Te in copper) at a higher laser fluence of 1.35 × 10 4W cm -2 than at 0.62 × 10 4W cm -2, which contradicted predictions from modelling studies of ablation processes. With glass, there was an inverse logarithmic relationship between the extent of ablative and overall fractionation and element oxide melting point (OMPs), with elements with OMPs < 1000° C exhibiting overall concentration increases of 20-1340%. Fractionation during transport was quantitatively important for most certified elements in copper, and for the most volatile elements (Au, Ag, Bi, Te) in glass. Elements common to both matrices showed 50-100% higher ablative fractionation in copper, possibly because of greater heat conductance away from the ablation site causing increased element volatilisation or zone refinement. These differences between matrices indicate that non-matrix-matched standardisation is likely to provide inaccurate calibration of laser ablation inductively coupled plasma-mass spectrometry analyses of at least some elements.

  10. Surface ablation of inorganic transparent materials using 70W femtosecond pulses at 1MHz (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Mishchik, Konstantin; Gaudfrin, Kevin; Audouard, Eric F.; Mottay, Eric P.; Lopez, John

    2017-03-01

    Nowadays processing of transparent materials, such as glass, quartz, sapphire and others, is a subject of high interest for worldwide industry since these materials are widely used for mass markets such as consumer electronics, flat display panels manufacturing, optoelectronics or watchmaking industry. The key issue is to combine high throughput, low residual stress and good processing quality in order to avoid chipping and any post-processing step such as grinding or polishing. Complimentary to non-ablative techniques used for zero-kerf glass cutting, surface ablation of such materials is interesting for engraving, grooving as well as full ablation cutting. Indeed this technique enables to process complex parts including via or blind, open or closed, straight or small radius of curvature patterns. We report on surface ablation experiments on transparent materials using a high average power (70W) and high repetition rate (1 MHz) femtosecond laser. These experiments have been done at 1030nm and 515nm on different inorganic transparent materials, such as regular and strengthened glass, borosilicate glass or sapphire, in order to underline their different ablation behavior. Despite the heat accumulation that occurs above 100 kHz we have reached a good compromise between throughput and processing quality. The effects of fluence, pulse-to-pulse overlap and number of passes are discussed in terms of etch rate, ablation efficiency, optimum fluence, maximum achievable depth, micro cracks formation and residual stresses. These experimental results will be also compared with numerical calculations obtained owing to a simple engineering model based on the two-temperature description of the ultrafast ablation.

  11. Ablative Thermal Protection System Fundamentals

    NASA Technical Reports Server (NTRS)

    Beck, Robin A. S.

    2013-01-01

    This is the presentation for a short course on the fundamentals of ablative thermal protection systems. It covers the definition of ablation, description of ablative materials, how they work, how to analyze them and how to model them.

  12. Microwave endometrial ablation versus thermal balloon endometrial ablation (MEATBall): 5-year follow up of a randomised controlled trial.

    PubMed

    Sambrook, A M; Elders, A; Cooper, K G

    2014-05-01

    To compare long-term outcomes following microwave endometrial ablation (MEA™) and thermal balloon ablation (TBall). Follow up of a prospective, double-blind randomised controlled trial at 5 years. A teaching hospital in the UK. A total of 320 women eligible for and requesting endometrial ablation. Eligible women were randomised in a 1:1 ratio to undergo MEA or Tball. Postal questionnaires were sent to participants at a minimum of 5 years postoperatively to determine satisfaction with outcome, menstrual status, bleeding scores and quality of life measurement. Subsequent surgery was ascertained from the women and the hospital operative database. The primary outcome measure was overall satisfaction with treatment. Secondary outcomes included evaluation of menstrual loss, change in quality of life scores and subsequent surgery. Of the women originally randomised 217/314 (69.1%) returned questionnaires. Nonresponders were assumed to be treatment failures for data analysis. The primary outcome of satisfaction was similar in both groups (58% for MEA™ versus 53% for TBall, difference 5%; 95% CI -6 to 16%). Amenorrhoea rates were high following both techniques (51% versus 45%, difference 6%; 95% CI -5 to 17%). There was no significant difference in the hysterectomy rates between the two arms (9% versus 7%, difference 2%; 95% CI -5 to 9%). At 5 years post-treatment there were no significant clinical differences in patient satisfaction, menstrual status, quality of life scores or hysterectomy rates between MEA™ and Thermachoice 3, thermal balloon ablation. © 2014 Royal College of Obstetricians and Gynaecologists.

  13. Photoactive dye-enhanced tissue ablation for endoscopic laser prostatectomy.

    PubMed

    Ahn, Minwoo; Hau, Nguyen Trung; Van Phuc, Nguyen; Oh, Junghwan; Kang, Hyun Wook

    2014-11-01

    Laser light has been widely used as a surgical tool to treat benign prostate hyperplasia (BPH) over 20 years. Recently, application of high laser power up to 200 W was often reported to swiftly remove a large amount of prostatic tissue. The purpose of this study was to validate the feasibility of photoactive dye injection to enhance light absorption and eventually to facilitate tissue vaporization with low laser power. Chicken breast tissue was selected as a target tissue due to minimal optical absorption at the visible wavelength. Four biocompatible photoactive dyes, including amaranth (AR), black dye (BD), hemoglobin powder (HP), and endoscopic marker (EM), were selected and tested in vitro with a customized 532 nm laser system with radiant exposure ranging from 0.9 to 3.9 J/cm(2) . Light absorbance and ablation threshold were measured with UV-Vis spectrometer and Probit analysis, respectively, and compared to feature the function of the injected dyes. Ablation performance with dye-injection was evaluated in light of radiant exposure, dye concentration, and number of injection. Higher light absorption by injected dyes led to lower ablation threshold as well as more efficient tissue removal in the order of AR, BD, HP, and EM. Regardless of the injected dyes, ablation efficiency principally increased with radiant exposure, dye concentration, and number of injection. Among the dyes, AR created the highest ablation rate of 44.2 ± 0.2 µm/pulse due to higher absorbance and lower ablation threshold. High aspect ratios up to 7.1 ± 0.4 entailed saturation behavior in the tissue ablation injected with AR and BD, possibly resulting from plume shielding and increased scattering due to coagulation. Preliminary tests on canine prostate with a hydraulic injection system demonstrated that 80 W with dye injection yielded comparable ablation efficiency to 120 W with no injection, indicating 33% reduced laser power with almost equivalent performance. Due to

  14. TPS Ablator Technologies for Interplanetary Spacecraft

    NASA Technical Reports Server (NTRS)

    Curry, Donald M.

    2004-01-01

    This slide presentation reviews the status of Thermal Protection System (TPS) Ablator technologies and the preparation for use in interplanetary spacecraft. NASA does not have adequate TPS ablatives and sufficient selection for planned missions. It includes a comparison of shuttle and interplanetary TPS requirements, the status of mainline TPS charring ablator materials, a summary of JSC SBIR accomplishments in developing advanced charring ablators and the benefits of SBIR Ablator/fabrication technology.

  15. A study of the effect of selected material properties on the ablation performance of artificial graphite

    NASA Technical Reports Server (NTRS)

    Maahs, H. G.

    1972-01-01

    Eighteen material properties were measured on 45 different, commercially available, artificial graphites. Ablation performance of these same graphites were also measured in a Mach 2 airstream at a stagnation pressure of 5.6 atm. Correlations were developed, where possible, between pairs of the material properties. Multiple regression equations were then formulated relating ablation performance to the various material properties, thus identifying those material properties having the strongest effect on ablation performance. These regression equations reveal that ablation performance in the present test environment depends primarily on maximum grain size, density, ash content, thermal conductivity, and mean pore radius. For optimization of ablation performance, grain size should be small, ash content low, density and thermal conductivity high, and mean pore radius large.

  16. Performance of Er:YAG laser ablation of hard bone under different irrigation water cooling conditions

    NASA Astrophysics Data System (ADS)

    Beltrán Bernal, Lina M.; Shayeganrad, Gholamreza; Kosa, Gabor; Zelechowski, Marek; Rauter, Georg; Friederich, Niklaus; Cattin, Philippe C.; Zam, Azhar

    2018-02-01

    The biological applicability of the Erbium-doped Yttrium Aluminum Garnet (Er:YAG) laser in surgical processes is so far limited to hard dental tissues. Using the Er:YAG laser for bone ablation is being studied since it has shown good performance for ablating dental hard tissues at the wavelength 2.94 μm, which coincides with the absorption peak of water, one of the main components of hard tissue, like teeth and bone. To obtain a decent performance of the laser in the cutting process, we aim at examining the influence of sequenced water jet irrigation on both, the ablation rate and the prevention of carbonization while performing laser ablation of bone with fixed laser parameters. An Er:YAG laser at 2.94 μm wavelength, 940 mJ energy per pulse, 400 μs pulse width, and 10 Hz repetition rate is used for the ablation of a porcine femur bone under different pulsed water jet irrigation conditions. We used micro-computed tomography (micro-CT) scans to determine the geometry of the ablated areas. In addition, scanning electron microscopy (SEM) is used for qualitative observations for the presence of carbonization and micro-fractures on the ablated surfaces. We evaluate the performance of the laser ablation process for the different water jet conditions in terms of the ablation rate, quantified by the ablated volume per second and the ablation efficiency, calculated as the ablated volume per pulse energy. We provide an optimized system for laser ablation which delivers the appropriate amount of water to the bone and consequently, the bone is ablated in the most efficient way possible without carbonization.

  17. Numerical design of RF ablation applicator for hepatic cancer treatment

    NASA Astrophysics Data System (ADS)

    Rakhmadi, Aditya; Basari

    2017-02-01

    Currently, cancer has become one of health problems that is difficult to be overcomed. This disease is not only difficult to be cured, but also to be detected and may cause death. For this reason, RF ablation treatment method is proposed to cure cancer. RF ablation therapy is a method in which an applicator is inserted into the body to kill cancer cells by heating the cells. The cancer cells are exposed to the temperature more than 60°C in short duration (few second to few minutes) so thus cell destruction occurs locally. For the sake of the successful treatment, a minimally invasive method is selected in order for perfect local temperature distribution in cancer cells can be achieved. In this paper, a coax-fed dipole-type applicator with interstitial irradiation technique is proposed aimed at RF ablation into hepatic cells. Numerical simulation is performed to obtain a suitable geometric dimension at operating frequency around 2.45 GHz, in order to localize the ablation area. The proposed applicator is inserted into a simple phantom representing an adult human body model in which normal and cancerous liver cells. The simulated results show that the proposed applicator is able to operate at center frequency of 2.355 GHz with blood droplet-type ablation zone and the temperature around the cancer cell by 60°C can be achieved.

  18. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation.

    PubMed

    Al-Hadeethi, Y; Al-Jedani, S; Razvi, M A N; Saeed, A; Abdel-Daiem, A M; Ansari, M Shahnawaze; Babkair, Saeed S; Salah, Numan A; Al-Mujtaba, A

    2016-01-01

    Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS) technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM). Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX). The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased.

  19. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation

    PubMed Central

    Abdel-Daiem, A. M.; Ansari, M. Shahnawaze; Babkair, Saeed S.; Salah, Numan A.; Al-Mujtaba, A.

    2016-01-01

    Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS) technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM). Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX). The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased. PMID:27228169

  20. Ion acceleration enhanced by target ablation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhao, S.; State Key Laboratory of Nuclear Physics and Technology, and Key Lab of HEDPS, CAPT, Peking University, Beijing 100871; Institute of Radiation, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden

    2015-07-15

    Laser proton acceleration can be enhanced by using target ablation, due to the energetic electrons generated in the ablation preplasma. When the ablation pulse matches main pulse, the enhancement gets optimized because the electrons' energy density is highest. A scaling law between the ablation pulse and main pulse is confirmed by the simulation, showing that for given CPA pulse and target, proton energy improvement can be achieved several times by adjusting the target ablation.

  1. Laboratory Simulations of Micrometeoroid Ablation

    NASA Astrophysics Data System (ADS)

    Thomas, Evan Williamson

    Each day, several tons of meteoric material enters Earth's atmosphere, the majority of which consist of small dust particles (micrometeoroids) that completely ablate at high altitudes. The dust input has been suggested to play a role in a variety of phenomena including: layers of metal atoms and ions, nucleation of noctilucent clouds, effects on stratospheric aerosols and ozone chemistry, and the fertilization of the ocean with bio-available iron. Furthermore, a correct understanding of the dust input to the Earth provides constraints on inner solar system dust models. Various methods are used to measure the dust input to the Earth including satellite detectors, radar, lidar, rocket-borne detectors, ice core and deep-sea sediment analysis. However, the best way to interpret each of these measurements is uncertain, which leads to large uncertainties in the total dust input. To better understand the ablation process, and thereby reduce uncertainties in micrometeoroid ablation measurements, a facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to accelerate iron particles to relevant meteoric velocities (10-70 km/s). The particles are then introduced into a chamber pressurized with a target gas, and they partially or completely ablate over a short distance. An array of diagnostics then measure, with timing and spatial resolution, the charge and light that is generated in the ablation process. In this thesis, we present results from the newly developed ablation facility. The ionization coefficient, an important parameter for interpreting meteor radar measurements, is measured for various target gases. Furthermore, experimental ablation measurements are compared to predictions from commonly used ablation models. In light of these measurements, implications to the broader context of meteor ablation are discussed.

  2. Use of shear waves for diagnosis and ablation monitoring of prostate cancer: a feasibility study

    NASA Astrophysics Data System (ADS)

    Gomez, A.; Rus, G.; Saffari, N.

    2016-01-01

    Prostate cancer remains as a major healthcare issue. Limitations in current diagnosis and treatment monitoring techniques imply that there is still a need for improvements. The efficacy of prostate cancer diagnosis is still low, generating under and over diagnoses. High intensity focused ultrasound ablation is an emerging treatment modality, which enables the noninvasive ablation of pathogenic tissue. Clinical trials are being carried out to evaluate its longterm efficacy as a focal treatment for prostate cancer. Successful treatment of prostate cancer using non-invasive modalities is critically dependent on accurate diagnostic means and is greatly benefited by a real-time monitoring system. While magnetic resonance imaging remains the gold standard for prostate imaging, its wider implementation for prostate cancer diagnosis remains prohibitively expensive. Conventional ultrasound is currently limited to guiding biopsy. Elastography techniques are emerging as a promising real-time imaging method, as cancer nodules are usually stiffer than adjacent healthy prostatic tissue. In this paper, a new transurethral approach is proposed, using shear waves for diagnosis and ablation monitoring of prostate cancer. A finite-difference time domain model is developed for studying the feasibility of the method, and an inverse problem technique based on genetic algorithms is proposed for reconstructing the location, size and stiffness parameters of the tumour. Preliminary results indicate that the use of shear waves for diagnosis and monitoring ablation of prostate cancer is feasible.

  3. Femtosecond laser ablation of gold interdigitated electrodes for electronic tongues

    NASA Astrophysics Data System (ADS)

    Manzoli, Alexandra; de Almeida, Gustavo F. B.; Filho, José A.; Mattoso, Luiz H. C.; Riul, Antonio; Mendonca, Cleber R.; Correa, Daniel S.

    2015-06-01

    Electronic tongue (e-tongue) sensors based on impedance spectroscopy have emerged as a potential technology to evaluate the quality and chemical composition of food, beverages, and pharmaceuticals. E-tongues usually employ transducers based on metal interdigitated electrodes (IDEs) coated with a thin layer of an active material, which is capable of interacting chemically with several types of analytes. IDEs are usually produced by photolithographic methods, which are time-consuming and costly, therefore, new fabrication technologies are required to make it more affordable. Here, we employed femtosecond laser ablation with pulse duration of 50 fs to microfabricate gold IDEs having finger width from 2.3 μm up to 3.2 μm. The parameters used in the laser ablation technique, such as light intensity, scan speed and beam spot size have been optimized to achieve uniform IDEs, which were characterized by optical and scanning electron microscopy. The electrical properties of gold IDEs fabricated by laser ablation were evaluated by impedance spectroscopy, and compared to those produced by conventional photolithography. The results show that femtosecond laser ablation is a promising alternative to conventional photolithography for fabricating metal IDEs for e-tongue systems.

  4. Selective ablation of sub- and supragingival calculus with a frequency-doubled Alexandrite laser

    NASA Astrophysics Data System (ADS)

    Rechmann, Peter; Hennig, Thomas

    1995-05-01

    In a preceding trial the absorption characteristics of subgingival calculus were calculated using fluorescence emission spectroscopy (excitation laser: N2-laser, wavelength 337 nm, pulse duration 4 ns). Subgingival calculus seems to contain chromophores absorbing in the ultraviolet spectral region up to 420 nm. The aim of the actual study was the ablation of sub- and supragingival calculus using a frequency doubled Alexandrite-laser (wavelength 377 nm, pulse duration 100 ns, repetition rate 110 Hz). Extracted human teeth presenting sub- and supragingival calculus were irradiated perpendicular to their axis with a laser fluence of 1 Jcm-2. Using a standard application protocol calculus was irradiated at the enamel surface, at the junction between enamel and root, and at the root surface (located on dentin or on cementum). During the irradiation procedure an effective water cooling-system was engaged. For light microscopical investigations undecalcified histological sections were prepared after treatment. The histological sections revealed that a selective and total removal of calculus is possible at all locations without ablation of healthy enamel, dentin or cementum. Even low fluences provide us with a high effectiveness for the ablation of calculus. Thus, based on different absorption characteristics and ablation thresholds, engaging a frequency doubled Alexandrite-laser a fast and, even more, a selective ablation of sub- and supragingival calculus is possible without adverse side effects to the surrounding tissues. Even more, microbial dental plaque can be perfectly removed.

  5. Picosecond laser ablation of poly-L-lactide: Effect of crystallinity on the material response

    NASA Astrophysics Data System (ADS)

    Ortiz, Rocío; Quintana, Iban; Etxarri, Jon; Lejardi, Ainhoa; Sarasua, Jose-Ramon

    2011-11-01

    The picosecond laser ablation of poly-L-lactide (PLLA) as a function of laser fluence and degree of crystallinity was examined. The ablation parameters and the surface modifications were analyzed under various irradiation conditions using laser wavelengths ranging from the ultraviolet through the visible. When processing the amorphous PLLA, both energy threshold and topography varied considerably depending on laser wavelength. Laser irradiation showed a reduction in the energy ablation threshold as the degree of crystallinity increased, probably related to photomechanical effects involved in laser ablation with ultra-short pulses and the lower stress accommodation behavior of semicrystalline polymers. In particular, cooperative chain motions are impeded by the higher degree of crystallinity, showing fragile mechanical behavior and lower energy dissipation. The experimental results on ablation rate versus laser energy showed that UV laser ablation on semicrystalline PLLA was more efficient than the visible ablation, i.e., it exhibits higher etch rates over a wide range of pulse energy conditions. These results were interpreted in terms of photo-thermal and photo-chemical response of polymers as a function of material micro-structure and incident laser wavelength. High quality micro-grooves were produced in amorphous PLLA, reveling the potential of ultra-fast laser processing technique in the field of micro-structuring biocompatible and biodegradable polymers for biomedical applications.

  6. Biological Ablation of Sentinel Lymph Node Metastasis in Submucosally Invaded Early Gastrointestinal Cancer

    PubMed Central

    Kikuchi, Satoru; Kishimoto, Hiroyuki; Tazawa, Hiroshi; Hashimoto, Yuuri; Kuroda, Shinji; Nishizaki, Masahiko; Nagasaka, Takeshi; Shirakawa, Yasuhiro; Kagawa, Shunsuke; Urata, Yasuo; Hoffman, Robert M; Fujiwara, Toshiyoshi

    2015-01-01

    Currently, early gastrointestinal cancers are treated endoscopically, as long as there are no lymph node metastases. However, once a gastrointestinal cancer invades the submucosal layer, the lymph node metastatic rate rises to higher than 10%. Therefore, surgery is still the gold standard to remove regional lymph nodes containing possible metastases. Here, to avoid prophylactic surgery, we propose a less-invasive biological ablation of lymph node metastasis in submucosally invaded gastrointestinal cancer patients. We have established an orthotopic early rectal cancer xenograft model with spontaneous lymph node metastasis by implantation of green fluorescent protein (GFP)-labeled human colon cancer cells into the submucosal layer of the murine rectum. A solution containing telomerase-specific oncolytic adenovirus was injected into the peritumoral submucosal space, followed by excision of the primary rectal tumors mimicking the endoscopic submucosal dissection (ESD) technique. Seven days after treatment, GFP signals had completely disappeared indicating that sentinel lymph node metastasis was selectively eradicated. Moreover, biologically treated mice were confirmed to be relapse-free even 4 weeks after treatment. These results indicate that virus-mediated biological ablation selectively targets lymph node metastasis and provides a potential alternative to surgery for submucosal invasive gastrointestinal cancer patients. PMID:25523761

  7. Heat sink phenomenon of bipolar and monopolar radiofrequency ablation observed using polypropylene tubes for vessel simulation.

    PubMed

    Al-Alem, Ihssan; Pillai, Krishna; Akhter, Javed; Chua, Terence C; Morris, David L

    2014-06-01

    Radiofrequency ablation (RFA) is widely used for treating liver tumors; recurrence is common owing to proximity to blood vessels possibly due to the heat sink effect. We seek to investigate this phenomenon using unipolar and bipolar RFA on an egg white tumor tissue model and an animal liver model. Temperature profiles during ablation (with and without vessel simulation) were studied, using both bipolar and unipolar RFA probes by 4 strategically placed temperature leads to monitor temperature profile during ablation. The volume of ablated tissue was also measured. The volume ablated during vessel simulation confirmed the impact of the heat sink phenomenon. The heat sink effect of unipolar RFA was greater compared with bipolar RFA (ratio of volume affected 2:1) in both tissue and liver models. The volume ablated using unipolar RFA was less than the bipolar RFA (ratio of volume ablated = 1:4). Unipolar RFA achieved higher ablation temperatures (122°C vs 98°C). Unipolar RFA resulted in tissue damage beyond the vessel, which was not observed using bipolar RFA. Bipolar RFA ablates a larger tumor volume compared with unipolar RFA, with a single ablation. The impact of heat sink phenomenon in tumor ablation is less so with bipolar than unipolar RFA with sparing of adjacent vessel damage. © The Author(s) 2013.

  8. Ventricular fibrillation occurring after atrioventricular node ablation despite minimal difference between pre- and post-ablation heart rates.

    PubMed

    Squara, F; Theodore, G; Scarlatti, D; Ferrari, E

    2017-02-01

    We report the case of an 82-year-old man presenting with ventricular fibrillation (VF) occurring acutely after atrioventricular node (AVN) ablation. This patient had severe valvular cardiomyopathy, chronic atrial fibrillation (AF), and underwent prior to the AVN ablation a biventricular implantable cardiac defibrillator positioning. The VF was successfully cardioverted with one external electrical shock. What makes this presentation original is that the pre-ablation spontaneous heart rate in AF was slow (84 bpm), and that VF occurred after ablation despite a minimal heart rate drop of only 14 bpm. VF is the most feared complication of AVN ablation, but it had previously only been described in case of acute heart rate drop after ablation of at least 30 bpm (and more frequently>50 bpm). This case report highlights the fact that VF may occur after AVN ablation regardless of the heart rate drop, rendering temporary fast ventricular pacing mandatory whatever the pre-ablation heart rate. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  9. Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery

    PubMed Central

    Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J. F.

    2014-01-01

    Abstract. Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuries in the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential use of laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ=2.94  μm), titanium:sapphire femtosecond laser system (λ=1700  nm), and Nd:glass femtosecond laser (λ=1053  nm). Bovine samples were ablated at fluences of 8 to 18  J/cm2 with the erbium:YAG laser, at a power of 300±15  mW with the titanium:sapphire femtosecond system, and at an energy of 3  μJ/pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18  J/cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates. PMID:25200394

  10. Thermal Ablation of T1c Renal Cell Carcinoma: A Comparative Assessment of Technical Performance, Procedural Outcome, and Safety of Microwave Ablation, Radiofrequency Ablation, and Cryoablation.

    PubMed

    Zhou, Wenhui; Arellano, Ronald S

    2018-04-06

    To evaluate perioperative outcomes of thermal ablation with microwave (MW), radiofrequency (RF), and cryoablation for stage T1c renal cell carcinoma (RCC). A retrospective analysis of 384 patients (mean age, 71 y; range, 22-88 y) was performed between October 2006 and October 2016. Mean radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior, and location relative to polar lines; preoperative aspects and dimensions used for anatomic classification; and centrality index scores were 6.3, 7.9, and 2.7, respectively. Assessment of pre- and postablation serum blood urea nitrogen, creatinine, and estimated glomerular filtration rate was performed to assess functional outcomes. Linear regression analyses were performed to compare sedation medication dosages among the three treatment cohorts. Univariable and multivariable logistic regression analyses were performed to compare rates of residual disease and complications among treatment modalities. A total of 437 clinical stage T1N0M0 biopsy-proven RCCs measuring 1.2-6.9 cm were treated with computed tomography (CT)-guided MW ablation (n = 44; 10%), RF ablation (n = 347; 79%), or cryoablation (n = 46; 11%). There were no significant differences in patient demographic or tumor characteristics among cohorts. Complication rates and immediate renal function changes were similar among the three ablation modalities (P = .46 and P = .08, respectively). MW ablation was associated with significantly decreased ablation time (P < .05), procedural time (P < .05), and dosage of sedative medication (P < .05) compared with RF ablation and cryoablation. CT-guided percutaneous MW ablation is comparable to RF ablation or cryoablation for the treatment of stage T1N0M0 RCC with regard to treatment response and is associated with shorter treatment times and less sedation than RF ablation or cryoablation. In addition, the safety profile of CT-guided MW ablation is noninferior to those of RF ablation or

  11. Surface modification of biomaterials by pulsed laser ablation deposition and plasma/gamma polymerization

    NASA Astrophysics Data System (ADS)

    Rau, Kaustubh R.

    Surface modification of stainless-steel was carried out by two different methods: pulsed laser ablation deposition (PLAD) and a combined plasma/gamma process. A potential application was the surface modification of endovascular stents, to enhance biocompatibility. The pulsed laser ablation deposition process, had not been previously reported for modifying stents and represented a unique and potentially important method for surface modification of biomaterials. Polydimethylsiloxane (PDMS) elatomer was studied using the PLAD technique. Cross- linked PDMS was deemed important because of its general use for biomedical implants and devices as well as in other fields. Furthermore, PDMS deposition using PLAD had not been previously studied and any information gained on its ablation characteristics could be important scientifically and technologically. The studies reported here showed that the deposited silicone film properties had a dependence on the laser energy density incident on the target. Smooth, hydrophobic, silicone-like films were deposited at low energy densities (100-150 mJ/cm2). At high energy densities (>200 mJ/cm2), the films had an higher oxygen content than PDMS, were hydrophilic and tended to show a more particulate morphology. It was also determined that (1)the deposited films were stable and extremely adherent to the substrate, (2)silicone deposition exhibited an `incubation effect' which led to the film properties changing with laser pulse number and (3)films deposited under high vacuum were similar to films deposited at low vacuum levels. The mechanical properties of the PLAD films were determined by nanomechanical measurements which are based on the Atomic Force Microscope (AFM). From these measurements, it was possible to determine the modulus of the films and also study their scratch resistance. Such measurement techniques represent a significant advance over current state-of-the-art thin film characterization methods. An empirical model for

  12. Value of microwave ablation in treatment of large lesions of hepatocellular carcinoma.

    PubMed

    Medhat, Eman; Abdel Aziz, Ashraf; Nabeel, Mohammed; Elbaz, Tamer; Zakaria, Zeinab; Shousha, Hend; Amer, Ayman; Fouad Fathalah, Waleed; Maher, Rabab; Musa, Shereif

    2015-08-01

    Thermal ablative therapies continue to be favored as a safe and effective treatment for patients with non-resectable hepatocellular carcinoma (HCC). Percutaneous microwave ablative therapy, which is a relatively new technique, has the advantage in providing faster ablation of large tumors. This study aimed to evaluate microwave ablation in the treatment of large HCC (5-7 cm) and to assess its effect on local tumor progression, prognostic outcome and patients' survival. In all, 26 patients with large HCC lesions (5-7 cm) were managed in the multidisciplinary clinic of Kasr Al Ainy University hospital using microwave ablation. The treatment was performed with the patient under conscious sedation and analgesia and ultrasonography-guided using an HS AMICA microwave machine operating at frequency of 2450 MHz and a power up to 100 W. Multiple needle insertions were made in one or two sessions according to the size of the lesion. The complete ablation rate, local tumor progression and patients' overall survival were analyzed, and the efficacy and safety of MWA was evaluated. Complete ablation was achieved in 19/26 (73.1%). Local tumor progression was recorded in five treated lesions (19.2%). Distant tumor progression within the liver was recorded in six patients (23.1%), with a mean survival of 21.5 months. No procedure-related major complications or deaths were observed. Percutaneous microwave ablation is safe and effective in the treatment of large HCC tumors. Patients' survival and local tumor control were acceptable. © 2015 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

  13. Comparison of microbubble presence in the right heart during mechanochemical and radiofrequency ablation for varicose veins.

    PubMed

    Moon, K H; Dharmarajah, B; Bootun, R; Lim, C S; Lane, Tra; Moore, H M; Sritharan, K; Davies, A H

    2017-07-01

    Objective Mechanochemical ablation is a novel technique for ablation of varicose veins utilising a rotating catheter and liquid sclerosant. Mechanochemical ablation and radiofrequency ablation have no reported neurological side-effect but the rotating mechanism of mechanochemical ablation may produce microbubbles. Air emboli have been implicated as a cause of cerebrovascular events during ultrasound-guided foam sclerotherapy and microbubbles in the heart during ultrasound-guided foam sclerotherapy have been demonstrated. This study investigated the presence of microbubbles in the right heart during varicose vein ablation by mechanochemical abaltion and radiofrequency abaltion. Methods Patients undergoing great saphenous vein ablation by mechanochemical abaltion or radiofrequency ablation were recruited. During the ablative procedure, the presence of microbubbles was assessed using transthoracic echocardiogram. Offline blinded image quantification was performed using International Consensus Criteria grading guidelines. Results From 32 recruited patients, 28 data sets were analysed. Eleven underwent mechanochemical abaltion and 17 underwent radiofrequency abaltion. There were no neurological complications. In total, 39% (11/28) of patients had grade 1 or 2 microbubbles detected. Thirty-six percent (4/11) of mechanochemical abaltion patients and 29% (5/17) of radiofrequency ablation patients had microbubbles with no significant difference between the groups ( p=0.8065). Conclusion A comparable prevalence of microbubbles between mechanochemical abaltion and radiofrequency ablation both of which are lower than that previously reported for ultrasound-guided foam sclerotherapy suggests that mechanochemical abaltion may not confer the same risk of neurological events as ultrasound-guided foam sclerotherapy for treatment of varicose veins.

  14. The use of a novel method of endovenous steam ablation in treatment of great saphenous vein insufficiency: own experiences.

    PubMed

    Mlosek, R K; Woźniak, W; Gruszecki, L; Stapa, R Z

    2014-02-01

    Endovascular procedures are gaining more and more popularity as treatment of great saphenous vein (GSV) incompetence. The purpose of the present study was to assess the efficacy of steam GSV ablation. Steam ablation using the steam vein sclerosis system (CERMA, France) was performed in 20 patients with GSV incompetence. The efficacy of the procedure was evaluated using ultrasound and the following parameters were assessed: changes in lumen diameter, GSV wall thickness, reflux and presence/absence of blood flow. The GSV steam ablation resulted in the obliteration of the vein lumen in all patients - reflux or blood flow were not observed in any subject. A significant decrease of GSV lumen diameter and an increase of GSV wall thickness were also observed in all subjects following the procedure. No postoperative complications were noted. The steam ablation technique was also positively assessed by the patients. Steam ablation is an endovascular surgical technique, which can become popular and widely used due to its efficacy and safety. It is also easy to use and patient-friendly. The research on its use should be continued.

  15. Perioral Rejuvenation With Ablative Erbium Resurfacing.

    PubMed

    Cohen, Joel L

    2015-11-01

    Since the introduction of the scanning full-field erbium laser, misconceptions regarding ablative erbium resurfacing have resulted in its being largely overshadowed by ablative fractional resurfacing. This case report illustrates the appropriateness of full-field erbium ablation for perioral resurfacing. A patient with profoundly severe perioral photodamage etched-in lines underwent full-field ablative perioral resurfacing with an erbium laser (Contour TRL, Sciton Inc., Palo Alto, CA) that allows separate control of ablation and coagulation. The pre-procedure consultations included evaluation of the severity of etched-in lines, and discussion of patient goals, expectations, and appropriate treatment options, as well as a review of patient photos and post-treatment care required. The author generally avoids full-field erbium ablation in patients with Fitzpatrick type IV and above. For each of 2 treatment sessions (separated by approximately 4 months), the patient received (12 cc plain 2% lidodaine) sulcus blocks before undergoing 4 passes with the erbium laser at 150 μ ablation, no coagulation, and then some very focal 30 μ ablation to areas of residual lines still visualized through the pinpoint bleeding. Similarly, full-field ablative resurfacing can be very reliable for significant wrinkles and creping in the lower eyelid skin--where often a single treatment of 80 μ ablation, 50 μ coagulation can lead to a nice improvement. Standardized digital imaging revealed significant improvement in deeply etched rhytides without significant adverse events. For appropriately selected patients requiring perioral (or periorbital) rejuvenation, full-field ablative erbium resurfacing is safe, efficacious and merits consideration.

  16. Simulation of Pellet Ablation

    NASA Astrophysics Data System (ADS)

    Parks, P. B.; Ishizaki, Ryuichi

    2000-10-01

    In order to clarify the structure of the ablation flow, 2D simulation is carried out with a fluid code solving temporal evolution of MHD equations. The code includes electrostatic sheath effect at the cloud interface.(P.B. Parks et al.), Plasma Phys. Contr. Fusion 38, 571 (1996). An Eulerian cylindrical coordinate system (r,z) is used with z in a spherical pellet. The code uses the Cubic-Interpolated Psudoparticle (CIP) method(H. Takewaki and T. Yabe, J. Comput. Phys. 70), 355 (1987). that divides the fluid equations into non-advection and advection phases. The most essential element of the CIP method is in calculation of the advection phase. In this phase, a cubic interpolated spatial profile is shifted in space according to the total derivative equations, similarly to a particle scheme. Since the profile is interpolated by using the value and the spatial derivative value at each grid point, there is no numerical oscillation in space, that often appears in conventional spline interpolation. A free boundary condition is used in the code. The possibility of a stationary shock will also be shown in the presentation because the supersonic ablation flow across the magnetic field is impeded.

  17. The ablation threshold of Er;Cr:YSGG laser radiation in bone tissue

    NASA Astrophysics Data System (ADS)

    Benetti, Carolina; Zezell, Denise Maria

    2015-06-01

    In laser cut clinical applications, the use of energy densities lower than the ablation threshold causes increase of temperature of the irradiated tissue, which might result in an irreversible thermal damage. Hence, knowing the ablation threshold is crucial for insuring the safety of these procedures. The aim of this study was to determine the ablation threshold of the Er,Cr:YSGG laser in bone tissue. Bone pieces from jaws of New Zealand rabbits were cut as blocks of 5 mm × 8 mm and polished with sandpaper. The Er,Cr:YSGG laser used in this study had wavelength of 2780 nm, 20 Hz of frequency, and the irradiation condition was chosen so as to simulate the irradiation during a surgical procedure. The laser irradiation was performed with 12 different values of laser energy densities, between 3 J/cm2 and 42 J/cm2, during 3 seconds, resulting in the overlap of 60 pulses. This process was repeated in each sample, for all laser energy densities. After irradiation, the samples were analyzed by scanning electron microscope (SEM), and it was measured the crater diameter for each energy density. By fitting a curve that related the ablation threshold with the energy density and the corresponding diameter of ablation crater, it was possible to determine the ablation threshold. The results showed that the ablation threshold of the Er,Cr:YSGG in bone tissue was 1.95+/-0.42 J/cm2.

  18. Towards computer-assisted TTTS: Laser ablation detection for workflow segmentation from fetoscopic video.

    PubMed

    Vasconcelos, Francisco; Brandão, Patrick; Vercauteren, Tom; Ourselin, Sebastien; Deprest, Jan; Peebles, Donald; Stoyanov, Danail

    2018-06-27

    Intrauterine foetal surgery is the treatment option for several congenital malformations. For twin-to-twin transfusion syndrome (TTTS), interventions involve the use of laser fibre to ablate vessels in a shared placenta. The procedure presents a number of challenges for the surgeon, and computer-assisted technologies can potentially be a significant support. Vision-based sensing is the primary source of information from the intrauterine environment, and hence, vision approaches present an appealing approach for extracting higher level information from the surgical site. In this paper, we propose a framework to detect one of the key steps during TTTS interventions-ablation. We adopt a deep learning approach, specifically the ResNet101 architecture, for classification of different surgical actions performed during laser ablation therapy. We perform a two-fold cross-validation using almost 50 k frames from five different TTTS ablation procedures. Our results show that deep learning methods are a promising approach for ablation detection. To our knowledge, this is the first attempt at automating photocoagulation detection using video and our technique can be an important component of a larger assistive framework for enhanced foetal therapies. The current implementation does not include semantic segmentation or localisation of the ablation site, and this would be a natural extension in future work.

  19. CT-guided bipolar and multipolar radiofrequency ablation (RF ablation) of renal cell carcinoma: specific technical aspects and clinical results.

    PubMed

    Sommer, C M; Lemm, G; Hohenstein, E; Bellemann, N; Stampfl, U; Goezen, A S; Rassweiler, J; Kauczor, H U; Radeleff, B A; Pereira, P L

    2013-06-01

    This study was designed to evaluate the clinical efficacy of CT-guided bipolar and multipolar radiofrequency ablation (RF ablation) of renal cell carcinoma (RCC) and to analyze specific technical aspects between both technologies. We included 22 consecutive patients (3 women; age 74.2 ± 8.6 years) after 28 CT-guided bipolar or multipolar RF ablations of 28 RCCs (diameter 2.5 ± 0.8 cm). Procedures were performed with a commercially available RF system (Celon AG Olympus, Berlin, Germany). Technical aspects of RF ablation procedures (ablation mode [bipolar or multipolar], number of applicators and ablation cycles, overall ablation time and deployed energy, and technical success rate) were analyzed. Clinical results (local recurrence-free survival and local tumor control rate, renal function [glomerular filtration rate (GFR)]) and complication rates were evaluated. Bipolar RF ablation was performed in 12 procedures and multipolar RF ablation in 16 procedures (2 applicators in 14 procedures and 3 applicators in 2 procedures). One ablation cycle was performed in 15 procedures and two ablation cycles in 13 procedures. Overall ablation time and deployed energy were 35.0 ± 13.6 min and 43.7 ± 17.9 kJ. Technical success rate was 100 %. Major and minor complication rates were 4 and 14 %. At an imaging follow-up of 15.2 ± 8.8 months, local recurrence-free survival was 14.4 ± 8.8 months and local tumor control rate was 93 %. GFR did not deteriorate after RF ablation (50.8 ± 16.6 ml/min/1.73 m(2) before RF ablation vs. 47.2 ± 11.9 ml/min/1.73 m(2) after RF ablation; not significant). CT-guided bipolar and multipolar RF ablation of RCC has a high rate of clinical success and low complication rates. At short-term follow-up, clinical efficacy is high without deterioration of the renal function.

  20. Pulsed Laser Ablation Synthesis of Diamond Molecules in Supercritical Fluids

    NASA Astrophysics Data System (ADS)

    Nakahara, Sho; Stauss, Sven; Miyazoe, Hiroyuki; Shizuno, Tomoki; Suzuki, Minoru; Kataoka, Hiroshi; Sasaki, Takehiko; Terashima, Kazuo

    2010-09-01

    Nanocarbon materials have been synthesized by pulsed laser ablation (532 nm; 52 J/cm2; 7 ns; 10 Hz) of highly oriented pyrolytic graphite in adamantane-dissolved supercritical xenon at a temperature T = 290.2 K and pressure p = 5.86 MPa. Micro-Raman spectroscopy of the products revealed the presence of hydrocarbons possessing sp3 hybridized bonds also found in diamond structures. The synthesis of diamantane was confirmed by gas chromatography-mass spectrometry. The same measurements also indicate the possible synthesis of other diamondoids up to octamantane. Thus, laser ablation in supercritical fluids is proposed as one practical method of synthesizing diamondoids.

  1. Ablative heat shield design for space shuttle

    NASA Technical Reports Server (NTRS)

    Seiferth, R. W.

    1973-01-01

    Ablator heat shield configuration optimization studies were conducted for the orbiter. Ablator and reusable surface insulation (RSI) trajectories for design studies were shaped to take advantage of the low conductance of ceramic RSI and high temperature capability of ablators. Comparative weights were established for the RSI system and for direct bond and mechanically attached ablator systems. Ablator system costs were determined for fabrication, installation and refurbishment. Cost penalties were assigned for payload weight penalties, if any. The direct bond ablator is lowest in weight and cost. A mechanically attached ablator using a magnesium subpanel is highly competitive for both weight and cost.

  2. Artificial pneumothorax: a safe and simple method to relieve pain during microwave ablation of subpleural lung malignancy.

    PubMed

    Hou, Xiaowei; Zhuang, Xingjun; Zhang, Haiwen; Wang, Kai; Zhang, Yuanxin

    2017-08-01

    Microwave ablation has been extensively used for eliminating pulmonary tumors; however, it is usually associated with severe pain under local anesthesia. Decreasing the power and shortening the ablation time can help to relieve the pain; however, this leads to incomplete ablation and an increasing recurrence rate. This research aims to employ an artificial pneumothorax to increase both the curative effect and pain relief during the ablation procedure. From July 2013 to January 2015, nine patients presenting with 10 subpleural lung tumors (age: 44-78 years) with a high possibility of severe pain underwent the artificial pneumothorax during microwave ablation. The pain assessment scores and complications induced by the artificial pneumothorax were recorded and analyzed by a CT scan follow-up. The tumors of the nine patients were eliminated successfully using microwave ablation with artificial pneumothorax under local anesthesia. The pain caused by the ablation was relieved to a great extent with an average rate of 94.66% (range: 63.3%-100%) and all tumors were ablated completely. No severe complications occurred after the operation. The artificial pneumothorax is a reliable therapy to improve the curative effect of microwave ablation under local anesthesia by relieving the pain of the patients.

  3. Test and Analysis of Solid Rocket Motor Nozzle Ablative Materials

    NASA Technical Reports Server (NTRS)

    Clayton, J. Louie

    2017-01-01

    Asbestos free solid motor internal insulation samples were tested at the MSFC Hyperthermal Facility. Objectives of the test were to gather data for analog characterization of ablative and in-depth thermal performance of rubber materials subject to high enthalpy/pressure flow conditions. Tests were conducted over a range of convective heat fluxes for both inert and chemically reactive sub-sonic free stream gas flow. Instrumentation included use of total calorimeters, thermocouples, and a surface pyrometer for surface temperature measurement. Post-test sample forensics involved measurement of eroded depth, charred depth, total sample weight loss, and documentation of the general condition of the eroded profile. A complete Charring Material Ablator (CMA) style aero-thermal analysis was conducted for the test matrix and results compared to the measured data. In general, comparisons were possible for a number of the cases and the results show a limited predictive ability to model accurately both the ablative response and the in-depth temperature profiles. Lessons learned and modeling recommendations are made regarding future testing and modeling improvements that will increase understanding of the basic chemistry/physics associated with the complicated material ablation process of rubber materials.

  4. Femtosecond Laser Ablation Multicollector ICPMS Analysis of Uranium Isotopes in NIST Glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duffin, Andrew M.; Springer, Kellen WE; Ward, Jesse D.

    We have utilized femtosecond laser ablation coupled to multi-collector inductively couple plasma mass spectrometry to measure the uranium isotopic content of NIST 61x (x=0,2,4,6) glasses. The uranium content of these glasses is a linear two-component mixing between isotopically natural uranium and the isotopically depleted spike used in preparing the glasses. Laser ablation results match extremely well, generally within a few ppm, with solution analysis following sample dissolution and chemical separation. In addition to isotopic data, sample utilization efficiency measurements indicate that over 1% of ablated uranium atoms reach a mass spectrometer detector, making this technique extremely efficient. Laser sampling alsomore » allows for spatial analysis and our data indicate that rare uranium concentration inhomogeneities exist in NIST 616 glass.« less

  5. Mechanistic Comparison of "Nearly Missed" Versus "On-Target" Rotor Ablation.

    PubMed

    Yamazaki, Masatoshi; Avula, Uma Mahesh R; Berenfeld, Omer; Kalifa, Jérôme

    2015-08-01

    This study used advanced optical mapping techniques to examine atrial fibrillation (AF) dynamics before and after 2 distinct electrogram-based ablation strategies: complex fractionated atrial electrograms (CFAEs) and DFmax/rotor ablation. Among the electrogram analytical features proposed to unravel the atrial regions that perpetuate AF, CFAEs, highest dominant frequency sites (DFmax), and, more recently, phase analysis-enabled rotor mapping have received the largest attention. Still, the mechanisms by which these approaches modulate AF dynamics and lead to AF termination are unknown. In Langendorff-perfused sheep hearts, AF was maintained by the continuous perfusion of acetylcholine and high-resolution endocardial-epicardial optical videos were recorded from the left atrial free wall and the posterior left atrium. Then, DFmax/rotor regions (n = 7), or CFAE regions harboring the highest wavebreak density (HWD) (n = 5), were targeted with a 4F ablation catheter (5 to 15 W, 30 to 60 s/point). Thereafter, we examined the changes in AF dynamics and whether AF terminated. DFmax/rotor point ablation resulted in a significant decrease in DFmax values. In 2 animals AF terminated, whereas in the remaining 5 animals the post-ablation DFmax domain remained in the vicinity of its pre-ablation location. However, after HWD/CFAEs density ablation, DFmax values did not change, AF did not terminate, and post-ablation DFmax domains relocated from the left atrial free wall to the pulmonary vein-posterior left atrium region. In another group of hearts (n = 12), we observed that upon a progressive increase in acetylcholine concentration-mimicking the acute electrophysiological changes occurring after ablation-3-dimensional rotors drifted from one atrial region to another along large gradients of myocardial thickness. "On-target" DFmax/rotor ablation leads to the annihilation of the fibrillation-driving rotor. This translates into large decreases in AF frequency or AF termination. In

  6. Comparison of Internal Energy Distributions of Ions Created by Electrospray Ionization and Laser Ablation-Liquid Vortex Capture-Electrospray Ionization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cahill, John F.; Kertesz, Vilmos; Ovchinnikova, Olga S.

    2015-06-27

    Recently a number of techniques have combined laser ablation with liquid capture for mass spectrometry spot sampling and imaging applications. The newly developed non-contact liquid-vortex capture probe has been used to efficiently collect 355 nm UV laser ablated material in a continuous flow solvent stream in which the captured material dissolves and then undergoes electrospray ionization. This sampling and ionization approach has produced what appear to be classic electrospray ionization spectra; however, the softness of this sampling/ionization process versus simple electrospray ionization has not been definitely determined. A series of benzlypyridinium salts, known as thermometer ions, were used to comparemore » internal energy distributions between electrospray ionization and the UV laser ablation liquid-vortex capture probe electrospray combination. Measured internal energy distributions were identical between the two techniques, even with differences in laser fluence (0.7-3.1 J cm-2) and when using UV-absorbing or non-UV-absorbing sample substrates. This data indicates ions formed directly by UV laser ablation, if any, are likely an extremely small constituent of the total ion signal observed. Instead, neutral molecules, clusters or particulates ejected from the surface during laser ablation, subsequently captured and dissolved in the flowing solvent stream then electrosprayed are the predominant source of ion signal observed. The electrospray ionization process used controls the softness of the technique.« less

  7. Naphthalene Planar Laser-Induced Fluorescence Imaging of Orion Multi-Purpose Crew Vehicle Heat Shield Ablation Products

    NASA Astrophysics Data System (ADS)

    Combs, Christopher S.; Clemens, Noel T.; Danehy, Paul M.

    2013-11-01

    The Orion Multi-Purpose Crew Vehicle (MPCV) calls for an ablative heat shield. In order to better design this heat shield and others that will undergo planetary entry, an improved understanding of the ablation process is required. Given that ablation is a multi-physics process involving heat and mass transfer, codes aiming to predict heat shield ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to visualize the transport of ablation products in a supersonic flow. Since ablation at reentry temperatures can be difficult to recreate in a laboratory setting it is desirable to create a limited physics problem and simulate the ablation process at relatively low temperature conditions using naphthalene. A scaled Orion MPCV model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel at various angles of attack in the current work. PLIF images have shown high concentrations of scalar in the capsule wake region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure. This work was supported by a NASA Office of the Chief Technologist's Space Technology Research Fellowship (NNX11AN55H).

  8. Effect of ablation time on femtosecond laser synthesis of Au- Ag colloidal nanoalloys

    NASA Astrophysics Data System (ADS)

    Hidayah, A. N.; Triyono, D.; Herbani, Y.; Isnaeni; Suliyanti, M. M.

    2018-03-01

    Au-Ag nanoalloys have been synthesized by laser irradiation technique. First, Au and Ag nanoparticles were prepared from Au and Ag pure metal (99.9%) ablated using an 800 nm femtosecond laser in distilled water. Using the same laser, Au and Ag nanoparticle with 1:1 ratio were subsequently mixed and irradiated with various irradiation time, i.e. 0, 5, 20, and 35 minutes. We varied the ablation time for each metal nanoparticles, i.e. 25 minutes and 1 hour to see its effect on the production of nanoalloys in the subsequent irradiation. Au-Ag nanoalloys were characterized and analyzed using transmission electron microscope and UV-Vis spectrophotometry. The result shows that Au-Ag nanoalloys were already formed in 20 minutes irradiation, either for the sample ablated for 25 minutes or 1 hour. The result of TEM shows that the size of Au-Ag nanoalloys prepared from 1 hour ablation was around 15.03 nm.

  9. Radiofrequency ablation of two femoral head chondroblastomas.

    PubMed

    Petsas, Theodore; Megas, Panagiotis; Papathanassiou, Zafiria

    2007-07-01

    Chondroblastoma is a rare benign cartilaginous bone tumor. Surgical resection is the treatment of choice for pain relief and prevention of further growth. Open surgical techniques are associated with complications, particularly when the tumors are located in deep anatomical sites. The authors performed RF ablation in two cases of subarticular femoral head chondroblastomas and emphasize its positive impact. The clinical course, the radiological findings and the post treatment results are discussed.

  10. Advanced Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    Early NASA missions (Gemini, Apollo, Mars Viking) employed new ablative TPS that were tailored for the entry environment. After 40 years, heritage ablative TPS materials using Viking or Pathfinder era materials are at or near their performance limits and will be inadequate for future exploration missions. Significant advances in TPS materials technology are needed in order to enable any subsequent human exploration missions beyond Low Earth Orbit. This poster summarizes some recent progress at NASA in developing families of advanced rigid/conformable and flexible ablators that could potentially be used for thermal protection in planetary entry missions. In particular the effort focuses technologies required to land heavy (approx.40 metric ton) masses on Mars to facilitate future exploration plans.

  11. TU-B-210-01: MRg HIFU - Bone and Soft Tissue Tumor Ablation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ghanouni, P.

    MR guided focused ultrasound (MRgFUS), or alternatively high-intensity focused ultrasound (MRgHIFU), is approved for thermal ablative treatment of uterine fibroids and pain palliation in bone metastases. Ablation of malignant tumors is under active investigation in sites such as breast, prostate, brain, liver, kidney, pancreas, and soft tissue. Hyperthermia therapy with MRgFUS is also feasible, and may be used in conjunction with radiotherapy and for local targeted drug delivery. MRI allows in situ target definition and provides continuous temperature monitoring and subsequent thermal dose mapping during HIFU. Although MRgHIFU can be very precise, treatment of mobile organs is challenging and advancedmore » techniques are required because of artifacts in MR temperature mapping, the need for intercostal firing, and need for gated HIFU or tracking of the lesion in real time. The first invited talk, “MR guided Focused Ultrasound Treatment of Tumors in Bone and Soft Tissue”, will summarize the treatment protocol and review results from treatment of bone tumors. In addition, efforts to extend this technology to treat both benign and malignant soft tissue tumors of the extremities will be presented. The second invited talk, “MRI guided High Intensity Focused Ultrasound – Advanced Approaches for Ablation and Hyperthermia”, will provide an overview of techniques that are in or near clinical trials for thermal ablation and hyperthermia, with an emphasis of applications in abdominal organs and breast, including methods for MRTI and tracking targets in moving organs. Learning Objectives: Learn background on devices and techniques for MR guided HIFU for cancer therapy Understand issues and current status of clinical MRg HIFU Understand strategies for compensating for organ movement during MRgHIFU Understand strategies for strategies for delivering hyperthermia with MRgHIFU CM - research collaboration with Philips.« less

  12. TU-B-210-02: MRg HIFU - Advanced Approaches for Ablation and Hyperthermia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moonen, C.

    2015-06-15

    MR guided focused ultrasound (MRgFUS), or alternatively high-intensity focused ultrasound (MRgHIFU), is approved for thermal ablative treatment of uterine fibroids and pain palliation in bone metastases. Ablation of malignant tumors is under active investigation in sites such as breast, prostate, brain, liver, kidney, pancreas, and soft tissue. Hyperthermia therapy with MRgFUS is also feasible, and may be used in conjunction with radiotherapy and for local targeted drug delivery. MRI allows in situ target definition and provides continuous temperature monitoring and subsequent thermal dose mapping during HIFU. Although MRgHIFU can be very precise, treatment of mobile organs is challenging and advancedmore » techniques are required because of artifacts in MR temperature mapping, the need for intercostal firing, and need for gated HIFU or tracking of the lesion in real time. The first invited talk, “MR guided Focused Ultrasound Treatment of Tumors in Bone and Soft Tissue”, will summarize the treatment protocol and review results from treatment of bone tumors. In addition, efforts to extend this technology to treat both benign and malignant soft tissue tumors of the extremities will be presented. The second invited talk, “MRI guided High Intensity Focused Ultrasound – Advanced Approaches for Ablation and Hyperthermia”, will provide an overview of techniques that are in or near clinical trials for thermal ablation and hyperthermia, with an emphasis of applications in abdominal organs and breast, including methods for MRTI and tracking targets in moving organs. Learning Objectives: Learn background on devices and techniques for MR guided HIFU for cancer therapy Understand issues and current status of clinical MRg HIFU Understand strategies for compensating for organ movement during MRgHIFU Understand strategies for strategies for delivering hyperthermia with MRgHIFU CM - research collaboration with Philips.« less

  13. Is Cryoballoon Ablation Preferable to Radiofrequency Ablation for Treatment of Atrial Fibrillation by Pulmonary Vein Isolation? A Meta-Analysis

    PubMed Central

    Xu, Junxia; Huang, Yingqun; Cai, Hongbin; Qi, Yue; Jia, Nan; Shen, Weifeng; Lin, Jinxiu; Peng, Feng; Niu, Wenquan

    2014-01-01

    Objective Currently radiofrequency and cryoballoon ablations are the two standard ablation systems used for catheter ablation of atrial fibrillation; however, there is no universal consensus on which ablation is the optimal choice. We therefore sought to undertake a meta-analysis with special emphases on comparing the efficacy and safety between cryoballoon and radiofrequency ablations by synthesizing published clinical trials. Methods and Results Articles were identified by searching the MEDLINE and EMBASE databases before September 2013, by reviewing the bibliographies of eligible reports, and by consulting with experts in this field. Data were extracted independently and in duplicate. There were respectively 469 and 635 patients referred for cryoballoon and radiofrequency ablations from 14 qualified clinical trials. Overall analyses indicated that cryoballoon ablation significantly reduced fluoroscopic time and total procedure time by a weighted mean of 14.13 (95% confidence interval [95% CI]: 2.82 to 25.45; P = 0.014) minutes and 29.65 (95% CI: 8.54 to 50.77; P = 0.006) minutes compared with radiofrequency ablation, respectively, whereas ablation time in cryoballoon ablation was nonsignificantly elongated by a weighted mean of 11.66 (95% CI: −10.71 to 34.04; P = 0.307) minutes. Patients referred for cryoballoon ablation had a high yet nonsignificant success rate of catheter ablation compared with cryoballoon ablation (odds ratio; 95% CI; P: 1.34; 0.53 to 3.36; 0.538), and cryoballoon ablation was also found to be associated with the relatively low risk of having recurrent atrial fibrillation (0.75; 0.3 to 1.88; 0.538) and major complications (0.46; 0.11 to 1.83; 0.269). There was strong evidence of heterogeneity and low probability of publication bias. Conclusion Our findings demonstrate greater improvement in fluoroscopic time and total procedure duration for atrial fibrillation patients referred for cryoballoon ablation than those for

  14. Radiofrequency ablation during continuous saline infusion can extend ablation margins

    PubMed Central

    Ishikawa, Toru; Kubota, Tomoyuki; Horigome, Ryoko; Kimura, Naruhiro; Honda, Hiroki; Iwanaga, Akito; Seki, Keiichi; Honma, Terasu; Yoshida, Toshiaki

    2013-01-01

    AIM: To determine whether fluid injection during radiofrequency ablation (RFA) can increase the coagulation area. METHODS: Bovine liver (1-2 kg) was placed on an aluminum tray with a return electrode affixed to the base, and the liver was punctured by an expandable electrode. During RFA, 5% glucose; 50% glucose; or saline fluid was infused continuously at a rate of 1.0 mL/min through the infusion line connected to the infusion port. The area and volume of the thermocoagulated region of bovine liver were determined after RFA. The Joule heat generated was determined from the temporal change in output during the RFA experiment. RESULTS: No liquid infusion was 17.3 ± 1.6 mL, similar to the volume of a 3-cm diameter sphere (14.1 mL). Mean thermocoagulated volume was significantly larger with continuous infusion of saline (29.3 ± 3.3 mL) than with 5% glucose (21.4 ± 2.2 mL), 50% glucose (16.5 ± 0.9 mL) or no liquid infusion (17.3 ± 1.6 mL). The ablated volume for RFA with saline was approximately 1.7-times greater than for RFA with no liquid infusion, representing a significant difference between these two conditions. Total Joule heat generated during RFA was highest with saline, and lowest with 50% glucose. CONCLUSION: RFA with continuous saline infusion achieves a large ablation zone, and may help inhibit local recurrence by obtaining sufficient ablation margins. RFA during continuous saline infusion can extend ablation margins, and may be prevent local recurrence. PMID:23483097

  15. Infrared thermography and thermocouple mapping of radiofrequency renal ablation to assess treatment adequacy and ablation margins.

    PubMed

    Ogan, Kenneth; Roberts, William W; Wilhelm, David M; Bonnell, Leonard; Leiner, Dennis; Lindberg, Guy; Kavoussi, Louis R; Cadeddu, Jeffrey A

    2003-07-01

    The primary disadvantage of renal tumor RF ablation is the inability to monitor the intraoperative propagation of the RF lesion with real-time imaging. We sought to assess whether adequately lethal temperatures are obtained at the margins of the intended ablation zone using laparoscopic thermography to monitor radiofrequency (RF) lesions in real time, thermocouple measurements, and histopathologic evaluation. Renal RF lesions were created under direct laparoscopic vision in the upper (1 cm diameter) and lower (2 cm) poles of the right kidney in 5 female pigs. The RF lesions were produced with the RITA generator and probe, set at 105 degrees C for 5-minute ablations. During RF treatment, a laparoscopic infrared (IR) camera measured the surface parenchymal temperatures, as did multiple thermocouples. The pigs were then either immediately killed (n = 3) or allowed to live for 2 weeks (n = 2). The kidneys were removed to correlate the temperature measurements with histologic analysis of the ablated lesion. Using a threshold temperature of greater than 70 degrees C for visual "temperature" color change, the IR camera identified the region of pathologic necrosis of the renal parenchyma during RF ablation. Thermocouple measurements demonstrated that the temperatures at the intended ablation radius reached 77.5 degrees C at the renal surface and 83.7 degrees C centrally, and temperatures 5 mm beyond the set radius reached 52.6 degrees C at the surface and 47.7 degrees C centrally. The average diameter of the gross lesion on the surface of the kidney measured 17.1 mm and 22.4 mm for 1-cm and 2-cm ablations, respectively. These surface measurements correlated with an average diameter of 16.1 mm and 15.9 mm (1-cm and 2-cm ablations, respectively) as measured with the IR camera. All cells within these ablation zones were nonviable by nicotinamide adenine dinucleotide diaphorase analysis. The average depth of the lesions measured 19 mm (1-cm ablation) and 25 mm (2-cm ablation

  16. Unambiguous characterization of gunshot residue particles using scanning laser ablation and inductively coupled plasma-mass spectrometry.

    PubMed

    Abrego, Zuriñe; Ugarte, Ana; Unceta, Nora; Fernández-Isla, Alberto; Goicolea, M Aranzazu; Barrio, Ramón J

    2012-03-06

    A new method based on scanning laser ablation and inductively coupled plasma-mass spectrometry (LA-ICPMS) for the detection and identification of gunshot residue (GSR) particles from firearms discharges has been developed. Tape lifts were used to collect inorganic residues from skin surfaces. The laser ablation pattern and ICPMS conditions were optimized for the detection of metals present in GSR, such as (121)Sb, (137)Ba, and (208)Pb. Other isotopes ((27)Al, (29)Si, (31)P, (33)S, (35)Cl, (39)K, (44)Ca, (57)Fe, (60)Ni, (63)Cu, (66)Zn, and (118)Sn) were monitored during the ICPMS analyses to obtain additional information to possibly classify the GSR particles as either characteristic of GSR or consistent with GSR. In experiments with real samples, different firearms, calibers, and ammunitions were used. The performed method evaluation confirms that the developed methodology can be used as an alternative to the standard scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) technique, with the significant advantage of drastically reducing the analysis time to less than 66 min.

  17. Outcomes of Radiofrequency Ablation for Dysplastic Barrett's Esophagus: A Comprehensive Review

    PubMed Central

    Iabichino, Giuseppe; Arena, Monica; Consolo, Pierluigi; Morace, Carmela; Opocher, Enrico; Mangiavillano, Benedetto

    2016-01-01

    Barrett's esophagus is a condition in which the normal squamous lining of the esophagus has been replaced by columnar epithelium containing intestinal metaplasia induced by recurrent mucosal injury related to gastroesophageal reflux disease. Barrett's esophagus is a premalignant condition that can progress through a dysplasia-carcinoma sequence to esophageal adenocarcinoma. Multiple endoscopic ablative techniques have been developed with the goal of eradicating Barrett's esophagus and preventing neoplastic progression to esophageal adenocarcinoma. For patients with high-grade dysplasia or intramucosal neoplasia, radiofrequency ablation with or without endoscopic resection for visible lesions is currently the most effective and safe treatment available. Recent data demonstrate that, in patients with Barrett's esophagus and low-grade dysplasia confirmed by a second pathologist, ablative therapy results in a statistically significant reduction in progression to high-grade dysplasia and esophageal adenocarcinoma. Treatment of dysplastic Barrett's esophagus with radiofrequency ablation results in complete eradication of both dysplasia and of intestinal metaplasia in a high proportion of patients with a low incidence of adverse events. A high proportion of treated patients maintain the neosquamous epithelium after successful treatment without recurrence of intestinal metaplasia. Following successful endoscopic treatment, endoscopic surveillance should be continued to detect any recurrent intestinal metaplasia and/or dysplasia. This paper reviews all relevant publications on the endoscopic management of Barrett's esophagus using radiofrequency ablation. PMID:28070182

  18. Deposition of functional nanoparticle thin films by resonant infrared laser ablation.

    NASA Astrophysics Data System (ADS)

    Haglund, Richard; Johnson, Stephen; Park, Hee K.; Appavoo, Kannatessen

    2008-03-01

    We have deposited thin films containing functional nanoparticles, using tunable infrared light from a picosecond free-electron laser (FEL). Thin films of the green light-emitting molecule Alq3 were first deposited by resonant infrared laser ablation at 6.68 μm, targeting the C=C ring mode of the Alq3. TiO2 nanoparticles 50-100 nm diameter were then suspended in a water matrix, frozen, and transferred by resonant infrared laser ablation at 2.94 μm through a shadow mask onto the Alq3 film. Photoluminescence was substantially enhanced in the regions of the film covered by the TiO2 nanoparticles. In a second experiment, gold nanoparticles with diameters in the range of 50-100 nm were suspended in the conducting polymer and anti-static coating material PEDOT:PSS, which was diluted by mixing with N-methyl pyrrolidinone (NMP). The gold nanoparticle concentration was 8-10% by weight. The mixture was frozen and then ablated by tuning the FEL to 3.47 μm, the C-H stretch mode of NMP. Optical spectroscopy of the thin film deposited by resonant infrared laser ablation exhibited the surface-plasmon resonance characteristic of the Au nanoparticles. These experiments illustrate the versatility of matrix-assisted resonant infrared laser ablation as a technique for depositing thin films containing functionalized nanoparticles.

  19. Planarization of Isolated Defects on ICF Target Capsule Surfaces by Pulsed Laser Ablation

    DOE PAGES

    Alfonso, Noel; Carlson, Lane C.; Bunn, Thomas L.

    2016-08-09

    Demanding surface quality requirements for inertial confinement fusion (ICF) capsules motivated the development of a pulsed laser ablation method to reduce or eliminate undesirable surface defects. The pulsed laser ablation technique takes advantage of a full surface (4π) capsule manipulation system working in combination with an optical profiling (confocal) microscope. Based on the defect topography, the material removal rate, the laser pulse energy and its beam profile, a customized laser raster pattern is derived to remove the defect. The pattern is a table of coordinates and number of pulses that dictate how the defect will be vaporized until its heightmore » is level with the capsule surface. This paper explains how the raster patterns are optimized to minimize surface roughness and how surface roughness after laser ablation is simulated. The simulated surfaces are compared with actual ablated surfaces. Large defects are reduced to a size regime where a tumble finishing process produces very high quality surfaces devoid of high mode defects. The combined polishing processes of laser ablation and tumble finishing have become routine fabrication steps for National Ignition Facility capsule production.« less

  20. Matrix Effects on Boron Containing Materials due to Laser Ablation Molecular Isotopic Spectrometry (LAMIS)

    NASA Astrophysics Data System (ADS)

    Brown, Staci R.; Akpovo, Charlemagne A.; Martinez, Jorge; Ford, Alan; Herbert, Kenley; Johnson, Lewis

    2014-03-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a spectroscopic technique that is used for the qualitative and quantitative analysis of materials in the liquid, solid, or gas phase. LIBS can also be used for the detection of isotopic shifts in atomic and diatomic species via Laser-Ablation Molecular Isotopic Spectroscopy (LAMIS). However, any additional elements that are entrained into the plasma other than the element of interest, can affect the extent of ablation and quality of spectra and hence, potentially obscure or aid in the relative abundance assessment for a given element. To address the importance of matrix effects, the isotopic analysis of boron obtained from boron oxide (BO) emission originating from different boron-containing compounds, such as boron nitride (BN), boric acid (H3BO3) , and borax (Na2B4O710H2O), via LIBS has been performed here. Each of these materials has different physical properties and elemental composition in order to illustrate possible challenges for the LAMIS method. A calibration-free model similar to that for the original LAMIS work is used to determine properties of the plasma as the matrix is changed. DTRA

  1. Development of a fine thermocouple-needle system for real-time feedback of thermal tumour ablation margin

    PubMed Central

    Ishizaka, H; Shiraishi, A; Awata, S; Shimizu, A; Hirasawa, S

    2011-01-01

    Thermal tumour ablation techniques such as radiofrequency (RF) ablation are applied for radical removal of local tumours as an easier, less invasive alternative to surgical resection. A serious drawback of thermal ablation, however, is that the ablation area cannot be accurately assessed during the procedure. To achieve real-time feedback and exact and safe ablation, a superfine thermocouple-needle system (TNS) comprising a 0.25-mm diameter thermocouple embedded in a 22-G, 15-cm-long needle was devised and efficacy was tested in vitro using porcine livers (n = 15) and in vivo using rabbit back muscles (n = 2) and livers (n = 3). A 17-gauge RF electrode with a 2 cm active tip was used for ablation. The TNS was inserted 1 cm from the active tip of the RF electrode and liver temperature around the electrode was measured concurrently. The RF current was cut off when the temperature reached 60°C or after 5 min at ≥50°C. Porcine livers and rabbit back muscles were then cut along a plane passing through the axes of the electrode and the TNS. In rabbit livers, contrast-enhanced CT was performed to evaluate ablation areas. Ablation areas in cut surfaces of porcine livers exhibited well-defined discoloured regions and the TNS tip precisely pinpointed the margin of the ablation area. Contrast-enhanced CT of rabbit livers showed the TNS tip accurately located at the margin of areas without contrast enhancement. These results indicate that the TNS can accurately show ablation margins and that placing the TNS tip at the intended ablation margin permits exact thermal ablation. PMID:21937618

  2. Brain Emboli After Left Ventricular Endocardial Ablation.

    PubMed

    Whitman, Isaac R; Gladstone, Rachel A; Badhwar, Nitish; Hsia, Henry H; Lee, Byron K; Josephson, S Andrew; Meisel, Karl M; Dillon, William P; Hess, Christopher P; Gerstenfeld, Edward P; Marcus, Gregory M

    2017-02-28

    Catheter ablation for ventricular tachycardia and premature ventricular complexes (PVCs) is common. Catheter ablation of atrial fibrillation is associated with a risk of cerebral emboli attributed to cardioversions and numerous ablation lesions in the low-flow left atrium, but cerebral embolic risk in ventricular ablation has not been evaluated. We enrolled 18 consecutive patients meeting study criteria scheduled for ventricular tachycardia or PVC ablation over a 9-month period. Patients undergoing left ventricular (LV) ablation were compared with a control group of those undergoing right ventricular ablation only. Patients were excluded if they had implantable cardioverter defibrillators or permanent pacemakers. Radiofrequency energy was used for ablation in all cases and heparin was administered with goal-activated clotting times of 300 to 400 seconds for all LV procedures. Pre- and postprocedural brain MRI was performed on each patient within a week of the ablation procedure. Embolic infarcts were defined as new foci of reduced diffusion and high signal intensity on fluid-attenuated inversion recovery brain MRI within a vascular distribution. The mean age was 58 years, half of the patients were men, half had a history of hypertension, and the majority had no known vascular disease or heart failure. LV ablation was performed in 12 patients (ventricular tachycardia, n=2; PVC, n=10) and right ventricular ablation was performed exclusively in 6 patients (ventricular tachycardia, n=1; PVC, n=5). Seven patients (58%) undergoing LV ablation experienced a total of 16 cerebral emboli, in comparison with zero patients undergoing right ventricular ablation ( P =0.04). Seven of 11 patients (63%) undergoing a retrograde approach to the LV developed at least 1 new brain lesion. More than half of patients undergoing routine LV ablation procedures (predominately PVC ablations) experienced new brain emboli after the procedure. Future research is critical to understanding the

  3. In Situ Geochemical Analysis and Age Dating of Rocks Using Laser Ablation-Miniature Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P.; Hecht, Michael H.; Hurowitz, Joel A.

    2012-01-01

    A miniaturized instrument for performing chemical and isotopic analysis of rocks has been developed. The rock sample is ablated by a laser and the neutral species produced are analyzed using the JPL-invented miniature mass spectrometer. The direct sampling of neutral ablated material and the simultaneous measurement of all the elemental and isotopic species are the novelties of this method. In this laser ablation-miniature mass spectrometer (LA-MMS) method, the ablated neutral atoms are led into the electron impact ionization source of the MMS, where they are ionized by a 70-eV electron beam. This results in a secondary ion pulse typically 10-100 microsecond wide, compared to the original 5-10-nanosecond laser pulse duration. Ions of different masses are then spatially dispersed along the focal plane of the magnetic sector of the miniature mass spectrometer and measured in parallel by a modified CCD (charge-coupled device) array detector capable of detecting ions directly. Compared to conventional scanning techniques, simultaneous measurement of the ion pulse along the focal plane effectively offers a 100% duty cycle over a wide mass range. LAMMS offers a more quantitative assessment of elemental composition than techniques that detect laser-ionized species produced directly in the ablation process because the latter can be strongly influenced by matrix effects that vary with the structure and geometry of the surface, the laser beam, and the ionization energies of the elements. The measurement of high-precision isotopic ratios and elemental composition of different rock minerals by LAMMS method has been demonstrated. The LA-MMS can be applied for the absolute age determination of rocks. There is no such instrument available presently in a miniaturized version that can be used for NASA space missions. Work is in progress in the laboratory for geochronology of rocks using LA-MMS that is based on K-Ar radiogenic dating technique.

  4. Achieving Bidirectional Long Delays In Pulmonary Vein Antral Lines Prior To Bidirectional Block In Patients With Paroxysmal Atrial Fibrillation (The Bi-Bi Technique For Atrial Fibrillation Ablation).

    PubMed

    Mina, Adel F; Warnecke, Nicholas L

    2016-01-01

    Background: Pulmonary Vein Antral isolation (PVAI) is currently the standard of care for both paroxysmal and persistent atrial fibrillation ablation. Reconnection to the pulmonary vein is the most common cause of recurrence of atrial fibrillation. Achieving the endpoint of bidirectional block (BDB) for cavotricuspid isthmus dependant flutter has improved our outcomes for atrial flutter ablation. With this we tried to achieve long delays in the pulmonary veins antral lines prior to complete isolation comparable to those delays found in patient with bidirectional block of atrial flutter lines. Study Objective: The objective of this paper was to evaluate feasibility and efficacy of achieving Bidirectional long delays in pulmonary vein antral lines prior to Bidirectional Block in patient with paroxysmal atrial fibrillation. Method: A retrospective analysis was performed on patients who had paroxysmal atrial fibrillation procedures at Unity Point Methodist from January 2015 to January 2016. 20 consecutive patients with paroxysmal atrial fibrillation who had AF ablation using the Bi-Bi technique were evaluated. Result: Mean age was 63, number of antiarrhythmic used prior to ablation was 1.4, mean left atrial size was 38 mm. Mean chads score was 1.3. Mean EF was 53%. Long delays in the left antral circumferential lines were achieved with mean delay of 142 milliseconds +/-100. Also long delays in the right antral circumferential lines were achieved with mean delay of 150 milliseconds +/-80. 95 % (19/20) of patients were free of any atrial arrhythmias and were off antiarrhythmic medications for AF post procedure. There was only one transient complication in one patient who developed a moderate pericardial effusion that was successfully drained with no hemodynamic changes. The only patient who had recurrence was found to have asymptomatic AF with burden on his device <1%, this patient was also found to have non PV triggers for his AF. In patients with only PV triggered AF

  5. A comparative analysis of clinical outcomes and disposable costs of different catheter ablation methods for the treatment of atrioventricular nodal reentrant tachycardia

    PubMed Central

    Berman, Adam E; Rivner, Harold; Chalkley, Robin; Heboyan, Vahé

    2017-01-01

    Background Catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is a commonly performed electrophysiology (EP) procedure. Few data exist comparing conventional (CONV) versus novel ablation strategies from both clinical and direct cost perspectives. We sought to investigate the disposable costs and clinical outcomes associated with three different ablation methodologies used in the ablation of AVNRT. Methods We performed a retrospective review of AVNRT ablations performed at Augusta University Medical Center from 2006 to 2014. A total of 183 patients were identified. Three different ablation techniques were compared: CONV manual radiofrequency (RF) (n=60), remote magnetic navigation (RMN)-guided RF (n=67), and cryoablation (CRYO) (n=56). Results Baseline demographics did not differ between the three groups except for a higher prevalence of cardiomyopathy in the RMN group (p<0.01). The clinical end point of interest was recurrent AVNRT following the index ablation procedure. A significantly higher number of recurrent AVNRT cases occurred in the CRYO group as compared to CONV and RMN (p=0.003; OR =7.75) groups. Cost-benefit analysis showed both CONV and RMN to be dominant compared to CRYO. Cost-minimization analysis demonstrated the least expensive ablation method to be CONV (mean disposable catheter cost = CONV US$2340; CRYO US$3515; RMN US$5190). Despite comparable clinical outcomes, the incremental cost of RMN over CONV averaged US$3094 per procedure. Conclusion AVNRT ablation using either CONV or RMN techniques is equally effective and associated with lower AVNRT recurrence rates than CRYO. CONV ablation carries significant disposable cost savings as compared to RMN, despite similar efficacy. PMID:29138585

  6. A comparative analysis of clinical outcomes and disposable costs of different catheter ablation methods for the treatment of atrioventricular nodal reentrant tachycardia.

    PubMed

    Berman, Adam E; Rivner, Harold; Chalkley, Robin; Heboyan, Vahé

    2017-01-01

    Catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is a commonly performed electrophysiology (EP) procedure. Few data exist comparing conventional (CONV) versus novel ablation strategies from both clinical and direct cost perspectives. We sought to investigate the disposable costs and clinical outcomes associated with three different ablation methodologies used in the ablation of AVNRT. We performed a retrospective review of AVNRT ablations performed at Augusta University Medical Center from 2006 to 2014. A total of 183 patients were identified. Three different ablation techniques were compared: CONV manual radiofrequency (RF) (n=60), remote magnetic navigation (RMN)-guided RF (n=67), and cryoablation (CRYO) (n=56). Baseline demographics did not differ between the three groups except for a higher prevalence of cardiomyopathy in the RMN group ( p <0.01). The clinical end point of interest was recurrent AVNRT following the index ablation procedure. A significantly higher number of recurrent AVNRT cases occurred in the CRYO group as compared to CONV and RMN ( p =0.003; OR =7.75) groups. Cost-benefit analysis showed both CONV and RMN to be dominant compared to CRYO. Cost-minimization analysis demonstrated the least expensive ablation method to be CONV (mean disposable catheter cost = CONV US$2340; CRYO US$3515; RMN US$5190). Despite comparable clinical outcomes, the incremental cost of RMN over CONV averaged US$3094 per procedure. AVNRT ablation using either CONV or RMN techniques is equally effective and associated with lower AVNRT recurrence rates than CRYO. CONV ablation carries significant disposable cost savings as compared to RMN, despite similar efficacy.

  7. Comparison of transcatheter laser and direct-current shock ablation of endocardium near tricuspid anulus

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Zhen; Wang, Shi-Wen; Li, Junheng

    1993-03-01

    Forty to eighty percent of the patients with accessory pathways (APs) manifest themselves by tachyarrhythmias. Many of these patients needed either life-long medical therapy or surgery. In order to avoid the discomfort and expenses in surgical procedures, closed chest percutaneous catheter ablation of APs became a potentially desirable therapeutic approach. Many investigations indicated that ablation of right APs by transcatheter direct current (dc) shock could cause life-threatening arrhythmias, right coronary arterical (RCA) spasm, etc. With the development of transcatheter laser technique, it has been used in drug-incurable arrhythmias. The results show that laser ablation is much safer than surgery and electric shock therapy. The purpose of this study is to explore the effectiveness, advantages, and complications with transcatheter Nd:YAG laser and dc shock in the ablation of right atrioventricular accessory pathways in the atrium near the tricuspid annulus (TA) in 20 dogs.

  8. Quantifying Local Ablation Rates for the Greenland Ice Sheet Using Terrestrial LIDAR

    NASA Astrophysics Data System (ADS)

    Kershner, C. M.; Pitcher, L. H.; LeWinter, A.; Finnegan, D. C.; Overstreet, B. T.; Miège, C.; Cooper, M. G.; Smith, L. C.; Rennermalm, A. K.

    2016-12-01

    Quantifying accurate ice surface ablation or melt rates for the Greenland Ice Sheet is important for calibrating and validating surface mass balance models and constraining sea level rise estimates. Common practice is to monitor surface ablation at defined points by manually measuring ice surface lowering in relation to stakes inserted into the ice / snow. However, this method does not account for the effects of local topography, solar zenith angle, and local variations in ice surface albedo/impurities on ablation rates. To directly address these uncertainties, we use a commercially available terrestrial LIDAR scanner (TLS) to monitor daily melt rates in the ablation zone of the Greenland Ice Sheet for 7 consecutive days in July 2016. Each survey is registered to previous scans using retroreflective cylinders and is georeferenced using static GPS measurements. Bulk ablation will be calculated using multi-temporal differential LIDAR techniques, and difficulties in referencing scans and collecting high quality surveys in this dynamic environment will be discussed, as well as areas for future research. We conclude that this novel application of TLS technology provides a spatially accurate, higher fidelity measurements of ablation across a larger area with less interpolation and less time spent than using traditional manual point based methods alone. Furthermore, this sets the stage for direct calibration, validation and cross-comparison with existing airborne (e.g. NASA's Airborne Topographic Mapper - ATM - onboard Operation IceBridge and NASA's Land, Vegetation & Ice Sensor - LVIS) and forthcoming spaceborne sensors (e.g. NASA's ICESat-2).

  9. Endoscopic Radiofrequency Ablation-Assisted Resection of Juvenile Nasopharyngeal Angiofibroma: Comparison with Traditional Endoscopic Technique.

    PubMed

    McLaughlin, Eamon J; Cunningham, Michael J; Kazahaya, Ken; Hsing, Julianna; Kawai, Kosuke; Adil, Eelam A

    2016-06-01

    To evaluate the feasibility of radiofrequency surgical instrumentation for endoscopic resection of juvenile nasopharyngeal angiofibroma (JNA) and to test the hypothesis that endoscopic radiofrequency ablation-assisted (RFA) resection will have superior intraoperative and/or postoperative outcomes as compared with traditional endoscopic (TE) resection techniques. Case series with chart review. Two tertiary care pediatric hospitals. Twenty-nine pediatric patients who underwent endoscopic transnasal resection of JNA from January 2000 to December 2014. Twenty-nine patients underwent RFA (n = 13) or TE (n = 16) JNA resection over the 15-year study period. Mean patient age was not statistically different between the 2 groups (P = .41); neither was their University of Pittsburgh Medical Center classification stage (P = .79). All patients underwent preoperative embolization. Mean operative times were not statistically different (P = .29). Mean intraoperative blood loss and the need for a transfusion were also not statistically different (P = .27 and .47, respectively). Length of hospital stay was not statistically different (P = .46). Recurrence rates did not differ between groups (P = .99) over a mean follow-up period of 2.3 years. There were no significant differences between RFA and TE resection in intraoperative or postoperative outcome parameters. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

  10. Catheter ablation of ventricular ectopy with para-hisian origin: importance of mapping both sides of the interventricular septum and understanding when to stop ablating.

    PubMed

    Madaffari, Antonio; Große, Anett; Raffa, Santi; Frommhold, Markus; Fink, Agnes; Geller, J Christoph

    2016-12-01

    Catheter ablation of para-Hisian premature ventricular contractions (PVCs) still represents a challenge and is a compromise between success and inadvertent AV block. We describe a possible strategy to address PVCs from this location with high-amplitude His-bundle potentials at the site of earliest activation.

  11. Sphere-enhanced microwave ablation (sMWA) versus bland microwave ablation (bMWA): technical parameters, specific CT 3D rendering and histopathology.

    PubMed

    Gockner, T L; Zelzer, S; Mokry, T; Gnutzmann, D; Bellemann, N; Mogler, C; Beierfuß, A; Köllensperger, E; Germann, G; Radeleff, B A; Stampfl, U; Kauczor, H U; Pereira, P L; Sommer, C M

    2015-04-01

    This study was designed to compare technical parameters during ablation as well as CT 3D rendering and histopathology of the ablation zone between sphere-enhanced microwave ablation (sMWA) and bland microwave ablation (bMWA). In six sheep-livers, 18 microwave ablations were performed with identical system presets (power output: 80 W, ablation time: 120 s). In three sheep, transarterial embolisation (TAE) was performed immediately before microwave ablation using spheres (diameter: 40 ± 10 μm) (sMWA). In the other three sheep, microwave ablation was performed without spheres embolisation (bMWA). Contrast-enhanced CT, sacrifice, and liver harvest followed immediately after microwave ablation. Study goals included technical parameters during ablation (resulting power output, ablation time), geometry of the ablation zone applying specific CT 3D rendering with a software prototype (short axis of the ablation zone, volume of the largest aligned ablation sphere within the ablation zone), and histopathology (hematoxylin-eosin, Masson Goldner and TUNEL). Resulting power output/ablation times were 78.7 ± 1.0 W/120 ± 0.0 s for bMWA and 78.4 ± 1.0 W/120 ± 0.0 s for sMWA (n.s., respectively). Short axis/volume were 23.7 ± 3.7 mm/7.0 ± 2.4 cm(3) for bMWA and 29.1 ± 3.4 mm/11.5 ± 3.9 cm(3) for sMWA (P < 0.01, respectively). Histopathology confirmed the signs of coagulation necrosis as well as early and irreversible cell death for bMWA and sMWA. For sMWA, spheres were detected within, at the rim, and outside of the ablation zone without conspicuous features. Specific CT 3D rendering identifies a larger ablation zone for sMWA compared with bMWA. The histopathological signs and the detectable amount of cell death are comparable for both groups. When comparing sMWA with bMWA, TAE has no effect on the technical parameters during ablation.

  12. Effect of Tumor Complexity and Technique on Efficacy and Complications after Percutaneous Microwave Ablation of Stage T1a Renal Cell Carcinoma: A Single-Center, Retrospective Study.

    PubMed

    Klapperich, Marki E; Abel, E Jason; Ziemlewicz, Timothy J; Best, Sara; Lubner, Meghan G; Nakada, Stephen Y; Hinshaw, J Louis; Brace, Christopher L; Lee, Fred T; Wells, Shane A

    2017-07-01

    Purpose To evaluate the effects of tumor complexity and technique on early and midterm oncologic efficacy and rate of complications for 100 consecutive biopsy-proved stage T1a renal cell carcinomas (RCCs) treated with percutaneous microwave ablation. Materials and Methods This HIPAA-compliant, single-center retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety-six consecutive patients (68 men, 28 women; mean age, 66 years ± 9.4) with 100 stage T1a N0M0 biopsy-proved RCCs (median diameter, 2.6 cm ± 0.8) underwent percutaneous microwave ablation between March 2011 and June 2015. Patient and procedural data were collected, including body mass index, comorbidities, tumor histologic characteristics and grade, RENAL nephrometry score, number of antennas, generator power, and duration of ablation. Technical success, local tumor progression, and presence of complications were assessed at immediate and follow-up imaging. The Kaplan-Meier method was used for survival analyses. Results Technical success was achieved for all 100 tumors (100%), including 47 moderately and five highly complex RCCs. Median clinical and imaging follow-up was 17 months (range, 0-48 months) and 15 months (range, 0-44 months), respectively. No change in estimated glomerular filtration rate was noted after the procedure (P = .49). There were three (3%) procedure-related complications and six (6%) delayed complications, all urinomas. One case of local tumor progression (1%) was identified 25 months after the procedure. Three-year local progression-free survival, cancer-specific survival, and overall survival were 88% (95% confidence interval: 0.52%, 0.97%), 100% (95% confidence interval: 1.0%, 1.0%), and 91% (95% confidence interval: 0.51%, 0.99%), respectively. Conclusion Percutaneous microwave ablation is an effective and safe treatment option for stage T1a RCC, regardless of tumor complexity. Long-term follow-up is needed

  13. Ablation by-products of dental materials from the Er:YAG laser and the dental handpiece

    NASA Astrophysics Data System (ADS)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-05-01

    Recently there has been much interest in lasers and their potential use to replace the dental drill. The research has been directed towards vital dental tissues. It must be understood that any laser to be used in dentistry which will replace the dental drill must also ablate and remove existing dental materials. Some concern exists about the ablation products when the Er:YAG laser is used to ablate dental materials. It is incumbent on the professionals using these lasers to understand the materials being produced by these lasers and protect themselves and their patients from possible toxic products. It is the intent of this paper to evaluate the products produced by the ablation of both dental amalgam and composite dental restorative materials and compare them with those produced by the traditional dental handpiece (drill).

  14. Robot-assisted radiofrequency ablation of a sacral S1-S2 aggressive hemangioma.

    PubMed

    Kaoudi, A; Capel, C; Chenin, L; Peltier, J; Lefranc, M

    2018-05-16

    Aggressive vertebral hemangiomas are rare tumors of the spine. The treatment management strategy usually consists of vertebroplasty, radiation therapy or in rare cases of surgical strategy. We present a case of a bulging sacral S1-S2 hemangioma in the spinal canal that could not be managed in the usual manner. Here, we demonstrate the usefulness of radiofrequency ablation technique as an alternative treatment as well as robotic assistance for optimal placement of the ablation probe within the lesion. Copyright © 2018. Published by Elsevier Inc.

  15. Microwave ablation for thyroid nodules: a new string to the bow for percutaneous treatments?

    PubMed

    Morelli, Francesco; Sacrini, Andrea; Pompili, Giovanni; Borelli, Anna; Panella, Silvia; Masu, Annamaria; De Pasquale, Loredana; Giacchero, Roberta; Carrafiello, Gianpaolo

    2016-12-01

    Thyroid nodules are a fairly common finding in general population and, even if most of them are benign, a treatment can be however necessary. In the last years, non surgical minimally invasive techniques have been developed to treat this pathology, starting from percutaneous ethanol injection (PEI), to laser ablation (LA), radiofrequency ablation (RFA) and, most recently, microwave ablation (MWA). We reviewed all medical literature searching in pubmed.gov the terms "microwave" & "thyroid". We found three original studies concerning MWA treatment, for a total of 263 patients (mean age 51.0 years; range, 15-80 years; male to female ratio 2.55) and 522 nodules. A total of 522 nodules (338 solid, 22 cystic, 162 mixed) in 263 patients were treated. Studies have shown a mean reduction in volume of thyroid nodules ranging from 45.9% to 65%. No study reported a significant and definitive change in laboratory parameters, except for one case (Heck et al. ). No studies have reported major complications after procedure. MWA is a new, promising technique among the minimally invasive treatments of thyroid nodules. Actually, the larger diameter of MW antenna seems to be the major limiting factor in the use of this technique. More studies are necessary to evaluate feasibility, safety and efficacy of the procedure.

  16. Evaluation of a Novel Thermal Accelerant for Augmentation of Microwave Energy during Image-guided Tumor Ablation.

    PubMed

    Park, William Keun Chan; Maxwell, Aaron Wilhelm Palmer; Frank, Victoria Elizabeth; Primmer, Michael Patrick; Collins, Scott Andrew; Baird, Grayson Luderman; Dupuy, Damian Edward

    2017-01-01

    The primary challenge in thermal ablation of liver tumors (e.g. hepatocellular carcinoma and hepatic colorectal cancer) is the relatively high recurrence rate (~30%) for which incomplete ablation at the periphery of the tumor is the most common reason. In an attempt to overcome this, we have developed a novel thermal accelerant (TA) agent capable of augmenting microwave energy from a distance normally unattainable by a single microwave ablation antenna. This cesium-based block co-polymer compound transforms from a liquid to a gel at body temperature and is intrinsically visible by computed tomography. Using an agarose phantom model, herein we demonstrate that both the rate and magnitude of temperature increase during microwave ablation were significantly greater in the presence of TA when compared with controls. These results suggest robust augmentation of microwave energy, and may translate into larger ablation zone volumes within biologic tissues. Further work using in vivo techniques is necessary to confirm these findings.

  17. Interaction thresholds in Er:YAG laser ablation of organic tissue

    NASA Astrophysics Data System (ADS)

    Lukac, Matjaz; Marincek, Marko; Poberaj, Gorazd; Grad, Ladislav; Mozina, Janez I.; Sustercic, Dusan; Funduk, Nenad; Skaleric, Uros

    1996-01-01

    Because of their unique properties with regard to the absorption in organic tissue, pulsed Er:YAG lasers are of interest for various applications in medicine, such as dentistry, dermatology, and cosmetic surgery. The relatively low thermal side effects, and surgical precision of erbium medical lasers have been attributed to the micro-explosive nature of their interaction with organic tissue. In this paper, we report on preliminary results of our study of the thresholds for tissue ablation, using an opto-acoustic technique. Two laser energy thresholds for the interaction are observed. The lower energy threshold is attributed to surface water vaporization, and the higher energy threshold to explosive ablation of thin tissue layers.

  18. Real time determination of the laser ablated mass by means of electric field-perturbation measurement

    NASA Astrophysics Data System (ADS)

    Pacheco, P.; Álvarez, J.; Sarmiento, R.; Bredice, F.; Sánchez-Aké, C.; Villagrán-Muniz, M.; Palleschi, V.

    2018-04-01

    A Nd:YAG ns-pulsed laser was used to ablate Al, Cd and Zn targets, which were placed between the plates of a planar charged capacitor. The plasma generates a transient redistribution of the electrical charges on the plates that can be measured as a voltage drop across a resistor connected to the ground plate. This signal is proportional to the capacitor applied voltage, the distance between the plates and the total number of ions produced in the ablation process which in turn is related to the laser energy and the ablated mass. After a series of pulses, the targets were weighed on a thermogravimetric balance to measure the ablated mass. Our results show that the electrical signal measured on the resistor is univocally related to the ablated mass from the target. Therefore, after a proper calibration depending on the material and the experimental geometry, the electrical signal can be used for real time quantitative measurement of the ablated mass in pulsed laser generated plasma experiments. The experiments were repeated on an aluminum target, with and without the presence of the external electric field in order to determine the possible influence of the applied electric field on the ablated mass.

  19. Percutaneous Microwave Ablation of Renal Angiomyolipomas.

    PubMed

    Cristescu, Mircea; Abel, E Jason; Wells, Shane; Ziemlewicz, Timothy J; Hedican, Sean P; Lubner, Megan G; Hinshaw, J Louis; Brace, Christopher L; Lee, Fred T

    2016-03-01

    To evaluate the safety and efficacy of US-guided percutaneous microwave (MW) ablation in the treatment of renal angiomyolipoma (AML). From January 2011 to April 2014, seven patients (5 females and 2 males; mean age 51.4) with 11 renal AMLs (9 sporadic type and 2 tuberous sclerosis associated) with a mean size of 3.4 ± 0.7 cm (range 2.4-4.9 cm) were treated with high-powered, gas-cooled percutaneous MW ablation under US guidance. Tumoral diameter, volume, and CT/MR enhancement were measured on pre-treatment, immediate post-ablation, and delayed post-ablation imaging. Clinical symptoms and creatinine were assessed on follow-up visits. All ablations were technically successful and no major complications were encountered. Mean ablation parameters were ablation power of 65 W (range 60-70 W), using 456 mL of hydrodissection fluid per patient, over 4.7 min (range 3-8 min). Immediate post-ablation imaging demonstrated mean tumor diameter and volume decreases of 1.8% (3.4-3.3 cm) and 1.7% (27.5-26.3 cm(3)), respectively. Delayed imaging follow-up obtained at a mean interval of 23.1 months (median 17.6; range 9-47) demonstrated mean tumor diameter and volume decreases of 29% (3.4-2.4 cm) and 47% (27.5-12.1 cm(3)), respectively. Tumoral enhancement decreased on immediate post-procedure and delayed imaging by CT/MR parameters, indicating decreased tumor vascularity. No patients required additional intervention and no patients experienced spontaneous bleeding post-ablation. Our early experience with high-powered, gas-cooled percutaneous MW ablation demonstrates it to be a safe and effective modality to devascularize and decrease the size of renal AMLs.

  20. Venous hemostasis postcatheter ablation of atrial fibrillation while under therapeutic levels of oral and intravenous anticoagulation.

    PubMed

    Issa, Ziad F; Amr, Bashar S

    2015-11-01

    Catheter ablation of atrial fibrillation (AF) requires utilizing multiple venous femoral sheaths in conjunction with aggressive periprocedural anticoagulation, which can lead to increased risk of vascular access complications. The objective of this study is to evaluate the safety and efficacy of the "figure-of-eight" ("F-8") suture technique for femoral venous hemostasis while on therapeutic doses of intravenous anticoagulation at the time of sheath removal. In this case-control analysis, 376 consecutive patients underwent AF ablation while on uninterrupted oral anticoagulation and received intraprocedural heparin. In the first 253 patients (the control group), manual pressure was used for femoral venous hemostasis after reversal of heparin effects. The subsequent 123 patients (the F-8 group) had femoral venous hemostasis using the F-8 suture technique and while under therapeutic heparin effects. The F-8 subcutaneous suture technique achieved adequate venous hemostasis in 98.4% of patients. As compared to the control group, there was significantly less frequent utilization of the FemoStop compression assist device (1.2 vs. 16.8%, p < 0.0001) and in a significantly shorter interval (6.8 ± 5.7 vs. 50.7 ± 12.2 min, p < 0.0001). Vascular access complications and thromboembolic events occurred in 9.8% in the F-8 group vs. 13.0% in the control group (p = 0.678). Immediate hemostasis of the femoral venous access sites after insertion of multiple sheaths for AF ablation in the presence of anticoagulation can be safely and effectively achieved using the F-8 suture technique. This technique helps minimize the period of inadequate anticoagulation immediately following ablation and shortens the time required to achieve adequate hemostasis.

  1. Wall ablation of heated compound-materials into non-equilibrium discharge plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Weizong; Kong, Linghan; Geng, Jinyue; Wei, Fuzhi; Xia, Guangqing

    2017-02-01

    show a non-equilibrium region near the plasma-wall interaction region and this indicates the need for the consideration of the influence of the possible departure from LTE in the plasma bulk on the determination of ablation rate.

  2. Sprayable lightweight ablative coating

    NASA Technical Reports Server (NTRS)

    Simpson, William G. (Inventor); Sharpe, Max H. (Inventor); Hill, William E. (Inventor)

    1991-01-01

    An improved lightweight, ablative coating is disclosed that may be spray applied and cured without the development of appreciable shrinkage cracks. The ablative mixture consists essentially of phenolic microballoons, hollow glass spheres, glass fibers, ground cork, a flexibilized resin binder, and an activated colloidal clay.

  3. Emerging needle ablation technology in urology.

    PubMed

    Leveillee, Raymond J; Pease, Karli; Salas, Nelson

    2014-01-01

    Thermal ablation of urologic tumors in the form of freezing (cryoablation) and heating (radiofrequency ablation) have been utilized successfully to treat and ablate soft tissue tumors for over 15 years. Multiple studies have demonstrated efficacy nearing that of extirpative surgery for certain urologic conditions. There are technical limitations to their speed and safety profile because of the physical limits of thermal diffusion. Recently, there has been a desire to investigate other forms of energy in an effort to circumvent the limitations of cryoblation and radiofrequency ablation. This review will focus on three relatively new energy applications as they pertain to tissue ablation: microwave, irreversible electroporation, and water vapor. High-intensity-focused ultrasound nor interstitial lasers are discussed, as there have been no recently published updates. Needle and probe-based ablative treatments will continue to play an important role. As three-dimensional imaging workstations move from the advanced radiologic interventional suite to the operating room, surgeons will likely still play a pivotal role in the +-application of these probe ablative devices. It is essential that the surgeon understands the fundamentals of these devices in order to optimize their application.

  4. Sphere-Enhanced Microwave Ablation (sMWA) Versus Bland Microwave Ablation (bMWA): Technical Parameters, Specific CT 3D Rendering and Histopathology

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gockner, T. L., E-mail: theresa.gockner@med.uni-heidelberg.de; Zelzer, S., E-mail: s.zelzer@dkfz-heidelberg.de; Mokry, T., E-mail: theresa.mokry@med.uni-heidelberg.de

    PurposeThis study was designed to compare technical parameters during ablation as well as CT 3D rendering and histopathology of the ablation zone between sphere-enhanced microwave ablation (sMWA) and bland microwave ablation (bMWA).MethodsIn six sheep-livers, 18 microwave ablations were performed with identical system presets (power output: 80 W, ablation time: 120 s). In three sheep, transarterial embolisation (TAE) was performed immediately before microwave ablation using spheres (diameter: 40 ± 10 μm) (sMWA). In the other three sheep, microwave ablation was performed without spheres embolisation (bMWA). Contrast-enhanced CT, sacrifice, and liver harvest followed immediately after microwave ablation. Study goals included technical parameters during ablation (resulting power output,more » ablation time), geometry of the ablation zone applying specific CT 3D rendering with a software prototype (short axis of the ablation zone, volume of the largest aligned ablation sphere within the ablation zone), and histopathology (hematoxylin-eosin, Masson Goldner and TUNEL).ResultsResulting power output/ablation times were 78.7 ± 1.0 W/120 ± 0.0 s for bMWA and 78.4 ± 1.0 W/120 ± 0.0 s for sMWA (n.s., respectively). Short axis/volume were 23.7 ± 3.7 mm/7.0 ± 2.4 cm{sup 3} for bMWA and 29.1 ± 3.4 mm/11.5 ± 3.9 cm{sup 3} for sMWA (P < 0.01, respectively). Histopathology confirmed the signs of coagulation necrosis as well as early and irreversible cell death for bMWA and sMWA. For sMWA, spheres were detected within, at the rim, and outside of the ablation zone without conspicuous features.ConclusionsSpecific CT 3D rendering identifies a larger ablation zone for sMWA compared with bMWA. The histopathological signs and the detectable amount of cell death are comparable for both groups. When comparing sMWA with bMWA, TAE has no effect on the technical parameters during ablation.« less

  5. Radiofrequency ablation of neuroendocrine liver metastases: the Middlesex experience.

    PubMed

    Gillams, A; Cassoni, A; Conway, G; Lees, W

    2005-01-01

    Current treatment options for neuroendocrine liver metastases are not widely applicable or not that effective. Image-guided thermal ablation offers the possibility of a minimally invasive, albeit palliative, treatment that decreases tumor volume, preserves most of the normal liver, and can be repeated several times. We report our experience with image-guided thermal ablation in 25 patients with unresectable liver metastases. Since 1990 we have treated 189 tumors at 66 treatment sessions in 25 patients (12 female, 13 male; median age, 56 years; age range, 26--78 years). Thirty treatments were performed with a solid-state laser, and 36 treatments were performed with radiofrequency ablation. All but one treatment was performed percutaneously under image guidance. Sixteen patients had metastases from carcinoid primaries, three from gastrinoma, two from insulinoma, and four from miscellaneous causes. Fourteen of 25 had symptoms from hormone secretion. Imaging follow-up was available in 19 patients at a median of 21 months (range, 4--75 months). There was a complete response in six patients, a partial response in seven, and stable disease in one; hence, tumor load was controlled in 14 of 19 patients (74%). Relief of hormone-related symptoms was achieved in nine of 14 patients (69%). The median survival period from the diagnosis of liver metastases was 53 months. One patient with end-stage cardiac disease died after a carcinoid crisis. There were eight (12%) complications: five local and three distant, four major and four minor. As a minimally invasive, readily repeatable procedure that can be used to ablate small tumors, preferably before patients become severely symptomatic, radiofrequency ablation can provide effective control of liver tumor volume in most patients over many years.

  6. [Endoscopic radiofrequency ablation for liver metastasis of colorectal cancer].

    PubMed

    Takahashi, Masahiro; Nitta, Hiroyuki; Sasaki, Akira; Fujita, Tomohiro; Obuchi, Toru; Hoshikawa, Koichi; Otsuka, Koki; Kawamura, Hidenobu; Higuchi, Taro; Asahi, Hiroshi; Saito, Kazuyoshi

    2005-10-01

    The application of radiofrequency ablation (RFA) for liver metastasis of colorectal cancer has not yet acquired an established status in clinical cancer therapy research. Removing as much tumor tissue as possible is desirable, but some cases do not allow optimal surgical ablation due to general condition of the patient and tumor status. We introduced endoscopic RFA for liver cancer in 2003, and have applied the procedure to 6 cases with H1 or H2 liver metastases of colorectal cancer to which surgical ablation could not be applied due to the poor general health of patients. Mean tumor diameter was 22.9 mm, and mean number of tumors per patient was 1.2. Tumor location was: S4, n = 2; S5, n = 1; S4, n = 1; S7, n = 2; and S8, n = 1. Mean frequency of session was 3.0. No complications occurred in any cases, and no reoperations were required. Although no recurrence of tumors in the vicinity of ablation was observed, 2 cases of each lung metastasis and intrahepatic recurrence were identified. Intrahepatic recurrence underwent hepatic arterial infusion (HAI) chemotherapy for simultaneous metastatic hepatic tumors (H2) prior to RFA, and relapses occurred in the metastatic focus where the efficacy of HAI was observed. At this point, 2 deaths were reported, 1 each from cancer and other diseases, and mean duration of survival after the procedure was 451.2 days. These results indicate that endoscopic RFA with good local control should be an available treatment for cases involving colorectal cancer with metastasis to the liver in which surgical ablation is difficult to apply.

  7. Determinations of rare earth element abundance and U-Pb age of zircons using multispot laser ablation-inductively coupled plasma mass spectrometry.

    PubMed

    Yokoyama, Takaomi D; Suzuki, Toshihiro; Kon, Yoshiaki; Hirata, Takafumi

    2011-12-01

    We have developed a new calibration technique for multielement determination and U-Pb dating of zircon samples using laser ablation-inductively coupled plasma mass spectrometry (ICPMS) coupled with galvanometric optics. With the galvanometric optics, laser ablation of two or more sample materials could be achieved in very short time intervals (~10 ms). The resulting sample aerosols released from different ablation pits or different solid samples were mixed and homogenized within the sample cell and then transported into the ICP ion source. Multiple spot laser ablation enables spiking of analytes or internal standard elements directly into the solid samples, and therefore the standard addition calibration method can be applied for the determination of trace elements in solid samples. In this study, we have measured the rare earth element (REE) abundances of two zircon samples (Nancy 91500 and Prešovice) based on the standard addition technique, using a direct spiking of analytes through a multispot laser ablation of the glass standard material (NIST SRM612). The resulting REE abundance data show good agreement with previously reported values within analytical uncertainties achieved in this study (10% for most elements). Our experiments demonstrated that nonspectroscopic interferences on 14 REEs could be significantly reduced by the standard addition technique employed here. Another advantage of galvanometric devices is the accumulation of sample aerosol released from multiple spots. In this study we have measured the U-Pb age of a zircon sample (LMR) using an accumulation of sample aerosols released from 10 separate ablation pits of low diameters (~8 μm). The resulting (238)U-(206)Pb age data for the LMR zircons was 369 ± 64 Ma, which is in good agreement with previously reported age data (367.6 ± 1.5 Ma). (1) The data obtained here clearly demonstrate that the multiple spot laser ablation-ICPMS technique can become a powerful approach for elemental and isotopic

  8. Surgical ablation for atrial fibrillation for two decades: are the results of new techniques equivalent to the Cox maze III procedure?

    PubMed

    Stulak, John M; Suri, Rakesh M; Burkhart, Harold M; Daly, Richard C; Dearani, Joseph A; Greason, Kevin L; Joyce, Lyle D; Park, Soon J; Schaff, Hartzell V

    2014-05-01

    sets. Although alternate energy sources offer the advantage of quicker application and the possibility of minimally invasive applications, the Cox maze III operation arguably remains the reference standard for the surgical treatment of AF and should still be considered, especially for patients for whom AF ablation is of critical importance. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  9. Pressure monitoring predicts pulmonary vein occlusion in cryoballoon ablation.

    PubMed

    Sunaga, Akihiro; Masuda, Masaharu; Asai, Mitsutoshi; Iida, Osamu; Okamoto, Shin; Ishihara, Takayuki; Nanto, Kiyonori; Kanda, Takashi; Tsujimura, Takuya; Matsuda, Yasuhiro; Okuno, Syota; Mano, Toshiaki

    2018-04-10

    Pulmonary venography is routinely used to confirm pulmonary vein (PV) occlusion during cryoballoon ablation. However, this technique is significantly limited by the risks associated with contrast media, such as renal injury and contrast allergy. We hypothesized that PV occlusion can be predicted by elevation of the balloon catheter tip pressure, avoiding the need for contrast media. Forty-eight consecutive patients with paroxysmal atrial fibrillation who underwent PV isolation with the cryoballoon technique were enrolled. The balloon catheter tip pressure was measured in each PV before and after balloon inflation. We analyzed 200 applications of cryoballoon ablation in 185 PVs (excluding 3 common PVs and 1 extremely small right inferior PV) of 48 patients (age, 70 ± 11 years; male, n = 28; mean left atrial diameter, 38 ± 6 mm). Compared with patients with unsuccessful occlusion, patients with successful occlusion demonstrated a larger change in pressure after balloon inflation (6 ± 8 vs. 2 ± 4 mmHg, P < 0.001), a lower minimum temperature (- 49 ± 6 vs. - 40 ± 8 °C, P < 0.001), and a higher PV isolation rate (97 vs. 64%, P < 0.001). The best cutoff value of a change in pressure for predicting PV occlusion was 4.5 mmHg, with a sensitivity of 67%, specificity of 83%, and predictive accuracy of 72%. Pressure monitoring is helpful to confirm PV occlusion during cryoballoon ablation.

  10. Diminished tektite ablation in the wake of a swarm

    NASA Technical Reports Server (NTRS)

    Sepri, P.; Chen, K. K.; Okeefe, J. A.

    1981-01-01

    Observations of ablation markings on tektite surfaces reveal that a large variation in aerodynamic heating must have occurred among the members of a swarm during atmospheric entry. In a few cases, the existence of jagged features indicates that these tektite surfaces may have barely reached the melting temperature. Such an observation seems to be incompatible with the necessarily large heating rates suffered by other tektites which exhibit the ring wave melt flow. A reconciliation is proposed in the form of a wake shielding model which is a natural consequence of swarm entry. Calculations indicate that the observed ablation variations are actually possible for swarm entry at greater than escape velocity. This aerodynamic conclusion provides support for the arguments favoring extraterrestrial origin of tektites.

  11. Modelling of pulsed electron beam induced graphite ablation: Sublimation versus melting

    NASA Astrophysics Data System (ADS)

    Ali, Muddassir; Henda, Redhouane

    2017-12-01

    Pulsed electron beam ablation (PEBA) has recently emerged as a very promising technique for the deposition of thin films with superior properties. Interaction of the pulsed electron beam with the target material is a complex process, which consists of heating, phase transition, and erosion of a small portion from the target surface. Ablation can be significantly affected by the nature of thermal phenomena taking place at the target surface, with subsequent bearing on the properties, stoichiometry and structure of deposited thin films. A two stage, one-dimensional heat conduction model is presented to describe two different thermal phenomena accounting for interaction of a graphite target with a polyenergetic electron beam. In the first instance, the thermal phenomena are comprised of heating, melting and vaporization of the target surface, while in the second instance the thermal phenomena are described in terms of heating and sublimation of the graphite surface. In this work, the electron beam delivers intense electron pulses of ∼100 ns with energies up to 16 keV and an electric current of ∼400 A to a graphite target. The temperature distribution, surface recession velocity, ablated mass per unit area, and ablation depth for the graphite target are numerically simulated by the finite element method for each case. Based on calculation findings and available experimental data, ablation appears to occur mainly in the regime of melting and vaporization from the surface.

  12. A new catheter design for combined radiofrequency ablation and optoacoustic treatment monitoring using copper-coated light-guides

    NASA Astrophysics Data System (ADS)

    Rebling, Johannes; Oyaga Landa, Francisco Javier; Deán-Ben, Xosé Luis; Razansky, Daniel

    2018-02-01

    Electrosurgery, i.e. the application of radiofrequency current for tissue ablation, is a frequently used treatment for many cardiac arrhythmias. Electrophysiological and anatomic mapping, as well as careful radiofrequency power control typically guide the radiofrequency ablation procedure. Despite its widespread application, accurate monitoring of the lesion formation with sufficient spatio-temporal resolution remains challenging with the existing imaging techniques. We present a novel integrated catheter for simultaneous radiofrequency ablation and optoacoustic monitoring of the lesion formation in real time and 3D. The design combines the delivery of both electric current and optoacoustic excitation beam in a single catheter consisting of copper-coated multimode light-guides and its manufacturing is described in detail. The electrical current causes coagulation and desiccation while the excitation light is locally absorbed, generating OA responses from the entire treated volume. The combined ablation-monitoring capabilities were verified using ex-vivo bovine tissue. The formed ablation lesions showed a homogenous coagulation while the ablation was monitored in realtime with a volumetric frame rate of 10 Hz over 150 seconds.

  13. Life-threatening hematuria requiring transcatheter embolization following radiofrequency ablation of renal cell carcinoma.

    PubMed

    Roach, H; Whittlestone, T; Callaway, M P

    2006-01-01

    Radiofrequency ablation is increasingly being acknowledged as a valid treatment for renal cell carcinoma in patients in whom definitive curative resection is deemed either undesirable or unsafe. A number of published series have shown the technique to have encouraging results and relatively low complication rates. In this article, we report a case of delayed life-threatening hematuria requiring transcatheter embolization of a bleeding intrarenal artery in a patient who had undergone imaging-guided radiofrequency ablation of a 3 cm renal cell carcinoma. To our knowledge, such a complication has not been reported previously.

  14. Visualization of risk structures for interactive planning of image guided radiofrequency ablation of liver tumors

    NASA Astrophysics Data System (ADS)

    Rieder, Christian; Schwier, Michael; Weihusen, Andreas; Zidowitz, Stephan; Peitgen, Heinz-Otto

    2009-02-01

    Image guided radiofrequency ablation (RFA) is becoming a standard procedure as a minimally invasive method for tumor treatment in the clinical routine. The visualization of pathological tissue and potential risk structures like vessels or important organs gives essential support in image guided pre-interventional RFA planning. In this work our aim is to present novel visualization techniques for interactive RFA planning to support the physician with spatial information of pathological structures as well as the finding of trajectories without harming vitally important tissue. Furthermore, we illustrate three-dimensional applicator models of different manufactures combined with corresponding ablation areas in homogenous tissue, as specified by the manufacturers, to enhance the estimated amount of cell destruction caused by ablation. The visualization techniques are embedded in a workflow oriented application, designed for the use in the clinical routine. To allow a high-quality volume rendering we integrated a visualization method using the fuzzy c-means algorithm. This method automatically defines a transfer function for volume visualization of vessels without the need of a segmentation mask. However, insufficient visualization results of the displayed vessels caused by low data quality can be improved using local vessel segmentation in the vicinity of the lesion. We also provide an interactive segmentation technique of liver tumors for the volumetric measurement and for the visualization of pathological tissue combined with anatomical structures. In order to support coagulation estimation with respect to the heat-sink effect of the cooling blood flow which decreases thermal ablation, a numerical simulation of the heat distribution is provided.

  15. Image-guided Tumor Ablation: Standardization of Terminology and Reporting Criteria—A 10-Year Update

    PubMed Central

    Solbiati, Luigi; Brace, Christopher L.; Breen, David J.; Callstrom, Matthew R.; Charboneau, J. William; Chen, Min-Hua; Choi, Byung Ihn; de Baère, Thierry; Dodd, Gerald D.; Dupuy, Damian E.; Gervais, Debra A.; Gianfelice, David; Gillams, Alice R.; Lee, Fred T.; Leen, Edward; Lencioni, Riccardo; Littrup, Peter J.; Livraghi, Tito; Lu, David S.; McGahan, John P.; Meloni, Maria Franca; Nikolic, Boris; Pereira, Philippe L.; Liang, Ping; Rhim, Hyunchul; Rose, Steven C.; Salem, Riad; Sofocleous, Constantinos T.; Solomon, Stephen B.; Soulen, Michael C.; Tanaka, Masatoshi; Vogl, Thomas J.; Wood, Bradford J.; Goldberg, S. Nahum

    2014-01-01

    Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes. © RSNA, 2014 Online supplemental material is available for this article. PMID:24927329

  16. Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update.

    PubMed

    Ahmed, Muneeb; Solbiati, Luigi; Brace, Christopher L; Breen, David J; Callstrom, Matthew R; Charboneau, J William; Chen, Min-Hua; Choi, Byung Ihn; de Baère, Thierry; Dodd, Gerald D; Dupuy, Damian E; Gervais, Debra A; Gianfelice, David; Gillams, Alice R; Lee, Fred T; Leen, Edward; Lencioni, Riccardo; Littrup, Peter J; Livraghi, Tito; Lu, David S; McGahan, John P; Meloni, Maria Franca; Nikolic, Boris; Pereira, Philippe L; Liang, Ping; Rhim, Hyunchul; Rose, Steven C; Salem, Riad; Sofocleous, Constantinos T; Solomon, Stephen B; Soulen, Michael C; Tanaka, Masatoshi; Vogl, Thomas J; Wood, Bradford J; Goldberg, S Nahum

    2014-10-01

    Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes. Online supplemental material is available for this article . © RSNA, 2014.

  17. Pulmonary vein stenosis following catheter ablation of atrial fibrillation.

    PubMed

    Pürerfellner, Helmut; Martinek, Martin

    2005-11-01

    This review provides an update on the mechanisms, incidence, and current management of significant pulmonary vein stenosis following catheter ablation of atrial fibrillation. Catheter ablation involving the pulmonary veins and the surrounding left atrial tissue is increasingly used to treat atrial fibrillation. In parallel with the fact that these procedures may cure a substantial proportion of patients, severe complications have been observed. Pulmonary vein stenosis is a new clinical entity produced by radiofrequency energy delivery mainly within or at the orifice of the pulmonary veins. The exact incidence is currently unknown because the diagnosis is dependent on the imaging modality and on the rigor with which patients are followed up. The optimal method for screening patients has not been determined. Stenosis of a pulmonary vein may be assessed by combining anatomic and functional imaging using computed tomographic or magnetic resonance imaging, transesophageal echocardiography, and lung scanning. Symptoms vary considerably and may be misdiagnosed, leading to severe clinical consequences. Current treatment strategies involve pulmonary vein dilatation or stenting; however, the restenosis rate remains high. The long-term outcome in patients with pulmonary vein stenosis is unclear. Strategies under development to prevent pulmonary vein stenosis include alternate energy sources and modified ablation techniques. Pulmonary vein stenosis following catheter ablation is a new clinical entity that has been described in various reports recently. There is much uncertainty with respect to causative factors, incidence, diagnosis, and treatment, and long-term sequelae are unclear.

  18. Navigational Guidance and Ablation Planning Tools for Interventional Radiology.

    PubMed

    Sánchez, Yadiel; Anvari, Arash; Samir, Anthony E; Arellano, Ronald S; Prabhakar, Anand M; Uppot, Raul N

    Image-guided biopsy and ablation relies on successful identification and targeting of lesions. Currently, image-guided procedures are routinely performed under ultrasound, fluoroscopy, magnetic resonance imaging, or computed tomography (CT) guidance. However, these modalities have their limitations including inadequate visibility of the lesion, lesion or organ or patient motion, compatibility of instruments in an magnetic resonance imaging field, and, for CT and fluoroscopy cases, radiation exposure. Recent advances in technology have resulted in the development of a new generation of navigational guidance tools that can aid in targeting lesions for biopsy or ablations. These navigational guidance tools have evolved from simple hand-held trajectory guidance tools, to electronic needle visualization, to image fusion, to the development of a body global positioning system, to growth in cone-beam CT, and to ablation volume planning. These navigational systems are promising technologies that not only have the potential to improve lesion targeting (thereby increasing diagnostic yield of a biopsy or increasing success of tumor ablation) but also have the potential to decrease radiation exposure to the patient and staff, decrease procedure time, decrease the sedation requirements, and improve patient safety. The purpose of this article is to describe the challenges in current standard image-guided techniques, provide a definition and overview for these next-generation navigational devices, and describe the current limitations of these, still evolving, next-generation navigational guidance tools. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Magnetic versus manual catheter navigation for ablation of free wall accessory pathways in children.

    PubMed

    Kim, Jeffrey J; Macicek, Scott L; Decker, Jamie A; Kertesz, Naomi J; Friedman, Richard A; Cannon, Bryan C

    2012-08-01

    Transcatheter ablation of accessory pathway (AP)-mediated tachycardia is routinely performed in children. Little data exist regarding the use of magnetic navigation (MN) and its potential benefits for ablation of AP-mediated tachycardia in this population. We performed a retrospective review of prospectively gathered data in children undergoing radiofrequency ablation at our institution since the installation of MN (Stereotaxis Inc, St. Louis, MO) in March 2009. The efficacy and safety between an MN-guided approach and standard manual techniques for mapping and ablation of AP-mediated tachycardia were compared. During the 26-month study period, 145 patients underwent radiofrequency ablation for AP-mediated tachycardia. Seventy-three patients were ablated with MN and 72 with a standard manual approach. There were no significant differences in demographic factors between the 2 groups with a mean cohort age of 13.1±4.0 years. Acute success rates were equivalent with 68 of 73 (93.2%) patients in the MN group being successfully ablated versus 68 of 72 (94.4%) patients in the manual group (P=0.889). During a median follow-up of 21.4 months, there were no recurrences in the MN group and 2 recurrences in the manual group (P=0.388). There were no differences in time to effect, number of lesions delivered, or average ablation power. There was also no difference in total procedure time, but fluoroscopy time was significantly reduced in the MN group at 14.0 (interquartile range, 3.8-23.9) minutes compared with the manual group at 28.1 (interquartile range, 15.3-47.3) minutes (P<0.001). There were no complications in either group. MN is a safe and effective approach to ablate AP-mediated tachycardia in children.

  20. Pleural Puncture that Excludes the Ablation Zone Decreases the Risk of Pneumothorax after Percutaneous Microwave Ablation in Porcine Lung

    PubMed Central

    Lee, Kyungmouk Steve; Takaki, Haruyuki; Yarmohammadi, Hooman; Srimathveeravalli, Govindarajan; Luchins, Kerith; Monette, Sébastien; Nair, Sreejit; Kishore, Sirish; Erinjeri, Joseph P.

    2017-01-01

    Purpose To test the hypothesis that the geometry of probe placement with respect to the pleural puncture site affects the risk of pneumothorax after microwave (MW) ablation in the lung. Materials and Methods Computed tomography–guided MW ablation of the lung was performed in 8 swine under general anesthesia and mechanical ventilation. The orientation of the 17-gauge probe was either perpendicular (90°) or parallel (< 30°) with respect to the pleural puncture site, and the ablation power was 30 W or 65 W for 5 minutes. After MW ablation, swine were euthanized, and histopathologic changes were assessed. Frequency and factors affecting pneumothorax were evaluated by multivariate analysis. Results Among 62 lung MW ablations, 13 (21%) pneumothoraces occurred. No statistically significant difference was noted in the rate of pneumothorax between the perpendicular and the parallel orientations of the probe (31% vs 14%; odds ratio [OR], 2.8; P = .11). The pneumothorax rate was equal for 65-W and 30-W ablation powers (21% and 21%; OR, 1.0; P = .94). Under multivariate analysis, 2 factors were independent positive predictors of pneumothorax: ablation zone inclusive of pleural insertion point (OR, 7.7; P = .02) and time since intubation (hours) (OR, 2.7; P = .02). Conclusions Geometries where the pleural puncture site excluded the ablation zone decreased pneumothorax in swine undergoing MW ablation in the lung. Treatment planning to ensure that the pleural puncture site excludes the subsequent ablation zone may reduce the rate of pneumothorax in patients undergoing MW ablation in the lung. PMID:25753501

  1. Thermal-mechanical modeling of laser ablation hybrid machining

    NASA Astrophysics Data System (ADS)

    Matin, Mohammad Kaiser

    2001-08-01

    Hard, brittle and wear-resistant materials like ceramics pose a problem when being machined using conventional machining processes. Machining ceramics even with a diamond cutting tool is very difficult and costly. Near net-shape processes, like laser evaporation, produce micro-cracks that require extra finishing. Thus it is anticipated that ceramic machining will have to continue to be explored with new-sprung techniques before ceramic materials become commonplace. This numerical investigation results from the numerical simulations of the thermal and mechanical modeling of simultaneous material removal from hard-to-machine materials using both laser ablation and conventional tool cutting utilizing the finite element method. The model is formulated using a two dimensional, planar, computational domain. The process simulation acronymed, LAHM (Laser Ablation Hybrid Machining), uses laser energy for two purposes. The first purpose is to remove the material by ablation. The second purpose is to heat the unremoved material that lies below the ablated material in order to ``soften'' it. The softened material is then simultaneously removed by conventional machining processes. The complete solution determines the temperature distribution and stress contours within the material and tracks the moving boundary that occurs due to material ablation. The temperature distribution is used to determine the distance below the phase change surface where sufficient ``softening'' has occurred, so that a cutting tool may be used to remove additional material. The model incorporated for tracking the ablative surface does not assume an isothermal melt phase (e.g. Stefan problem) for laser ablation. Both surface absorption and volume absorption of laser energy as function of depth have been considered in the models. LAHM, from the thermal and mechanical point of view is a complex machining process involving large deformations at high strain rates, thermal effects of the laser, removal of

  2. Bimodal electric tissue ablation (BETA): a study on ablation size when the anode is placed on the peritoneum and the liver.

    PubMed

    Tiong, Leong U; Finnie, John W; Field, John B; Maddern, Guy J

    2012-07-01

    cathode and the anode of the DC circuit. Research so far has shown that BETA works best when the anode is placed deep to the skin as the stratum corneum consisted of a layer of a-nucleated cells, which have high electrical resistivity. The liver could be the ideal location to place the anode as it has excellent electrical conductivity, therefore ensuring maximum tissue hydration around the cathode to produce the largest ablations possible. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Percutaneous microwave ablation of renal cell carcinoma using a high power microwave system: focus upon safety and efficacy.

    PubMed

    Filippiadis, D K; Gkizas, C; Chrysofos, M; Siatelis, A; Velonakis, G; Alexopoulou, E; Kelekis, A; Brountzos, E; Kelekis, N

    2017-12-04

    Percutaneous ablation is an expanding, minimally invasive approach for small- to medium-sized renal masses. The purpose of this study is to review safety, and mid-term efficacy of percutaneous microwave ablation (MWA) for Renal Cell Carcinoma (RCC) treatment using a high power microwave system. Institutional database research identified 50 consecutive patients with a single lesion resembling renal cell carcinoma in CT and MRI who underwent percutaneous microwave ablation using a high power microwave system. All patients underwent biopsy on the same session with ablation using an 18G semi-automatic soft tissue biopsy needle. Contrast-enhanced computed tomography or magnetic resonance imaging was used for post-ablation follow-up. Patient and tumour characteristics, microwave technique, complications and pattern of recurrence were evaluated. Mean patient age was 74 years (male-female: 31-19). Average lesion size was 3.1 cm (range 2.0-4.3 cm). Biopsy results report RCC (n = 48), inflammatory myofibroblastic tumour (n = 1), and non-diagnostic sample (n = 1). The 3-year overall survival was 95.8% (46/48). Two patients died during the 3-year follow-up period due to causes unrelated to the MW ablation and to the RCC. Minor complications including haematomas requiring nothing but observation occurred at 4% (2/50) of the cases. Local recurrence of 6.25% (3/48) was observed with 2/3 cases being re-treated achieving a total clinical success of 97.9% (47/48 lesions). Percutaneous microwave ablation of RCC using a high power microwave system is a safe and efficacious technique for the treatment of small- to medium-sized renal masses.

  4. Efficacy and Safety of Radiofrequency Ablation for Focal Hepatic Lesions Adjacent to Gallbladder: Reconfiguration of the Ablation Zone through Probe Relocation and Ablation Time Reduction.

    PubMed

    Choi, In Young; Kim, Pyo Nyun; Lee, Sung Gu; Won, Hyung Jin; Shin, Yong Moon

    2017-10-01

    To evaluate the safety and efficacy of radiofrequency (RF) ablation for treatment of focal hepatic lesions adjacent to the gallbladder with electrode relocation and ablation time reduction. Thirty-nine patients who underwent RF ablation for focal hepatic lesions adjacent to the gallbladder (≤ 10 mm) were evaluated retrospectively from January 2011 to December 2014 (30 men and 9 women; age range, 51-85 y; mean age, 65 y). Of 36 patients with hepatocellular carcinoma, 3 had a second treatment for recurrence (mean tumor size, 15 mm ± 6). Patients were divided into 2 subgroups based on lesion distance from the gallbladder: nonabutting (> 5 mm; n = 19) and abutting (≤ 5 mm; n = 20). Electrodes were inserted parallel to the gallbladder through the center of a tumor in the nonabutting group and through the center of the expected ablation zone between a 5-mm safety zone on the liver side and the gallbladder in the abutting group. Ablation time was decreased in proportion to the transverse diameter of the expected ablation zone. Technical success and technical effectiveness rates were 89.7% and 97.4%, respectively, with no significant differences between groups (P = 1.00). Local tumor progression was observed in 3 patients (1 in the nonabutting group and 2 in the abutting group; P = 1.00). There were no major complications. The gallbladder was thickened in 10 patients, with no significant difference between groups (P = .72). Biloma occurred in 1 patient in the nonabutting group. RF ablation with electrode relocation and reduction of ablation time can be a safe and effective treatment for focal hepatic lesions adjacent to the gallbladder. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

  5. Experimental studies and simulations of hydrogen pellet ablation in the stellarator TJ-II

    NASA Astrophysics Data System (ADS)

    Panadero, N.; McCarthy, K. J.; Koechl, F.; Baldzuhn, J.; Velasco, J. L.; Combs, S. K.; de la Cal, E.; García, R.; Hernández Sánchez, J.; Silvagni, D.; Turkin, Y.; TJ-II Team; W7-X Team

    2018-02-01

    Plasma core fuelling is a key issue for the development of steady-state scenarios in large magnetically-confined fusion devices, in particular for helical-type machines. At present, cryogenic pellet injection is the most promising technique for efficient fuelling. Here, pellet ablation and fuelling efficiency experiments, using a compact pellet injector, are carried out in electron cyclotron resonance and neutral beam injection heated plasmas of the stellarator TJ-II. Ablation profiles are reconstructed from light emissions collected by silicon photodiodes and a fast-frame camera system, under the assumptions that such emissions are loosely related to the ablation rate and that pellet radial acceleration is negligible. In addition, pellet particle deposition and fuelling efficiency are determined using density profiles provided by a Thomson scattering system. Furthermore, experimental results are compared with ablation and deposition profiles provided by the HPI2 pellet code, which is adapted here for the stellarators Wendelstein 7-X (W7-X) and TJ-II. Finally, the HPI2 code is used to simulate ablation and deposition profiles for pellets of different sizes and velocities injected into relevant W7-X plasma scenarios, while estimating the plasmoid drift and the fuelling efficiency of injections made from two W7-X ports.

  6. Optimal approach for complete liver tumor ablation using radiofrequency ablation: a simulation study.

    PubMed

    Givehchi, Sogol; Wong, Yin How; Yeong, Chai Hong; Abdullah, Basri Johan Jeet

    2018-04-01

    To investigate the effect of radiofrequency ablation (RFA) electrode trajectory on complete tumor ablation using computational simulation. The RFA of a spherical tumor of 2.0 cm diameter along with 0.5 cm clinical safety margin was simulated using Finite Element Analysis software. A total of 86 points inside one-eighth of the tumor volume along the axial, sagittal and coronal planes were selected as the target sites for electrode-tip placement. The angle of the electrode insertion in both craniocaudal and orbital planes ranged from -90° to +90° with 30° increment. The RFA electrode was simulated to pass through the target site at different angles in combination of both craniocaudal and orbital planes before being advanced to the edge of the tumor. Complete tumor ablation was observed whenever the electrode-tip penetrated through the epicenter of the tumor regardless of the angles of electrode insertion in both craniocaudal and orbital planes. Complete tumor ablation can also be achieved by placing the electrode-tip at several optimal sites and angles. Identification of the tumor epicenter on the central slice of the axial images is essential to enhance the success rate of complete tumor ablation during RFA procedures.

  7. Endovenous ablation of refluxing saphenous and perforating veins.

    PubMed

    Proebstle, Thomas; van den Bos, Renate

    2017-05-01

    Since the end of the nineties endovenous thermal ablation and more recently non-thermal, non-tumescent techniques have been developed and improved. Until now, because of their favourable side effect profile in conjunction to sustained efficacy, in many countries they already replaced high ligation and stripping in the treatment of refluxing saphenous veins as well as for treatment of perforators and selected tributaries. Now, studies and comparative trials are available with long-term follow-ups for most of the techniques, providing valid data on occlusion and reflux rates, side effect profiles, and health related quality of life.

  8. Spatially resolved in vivo plant metabolomics by laser ablation-based mass spectrometry imaging (MSI) techniques: LDI-MSI and LAESI

    PubMed Central

    Bartels, Benjamin; Svatoš, Aleš

    2015-01-01

    This short review aims to summarize the current developments and applications of mass spectrometry-based methods for in situ profiling and imaging of plants with minimal or no sample pre-treatment or manipulation. Infrared-laser ablation electrospray ionization and UV-laser desorption/ionization methods are reviewed. The underlying mechanisms of the ionization techniques–namely, laser ablation of biological samples and electrospray ionization–as well as variations of the LAESI ion source for specific targets of interest are described. PMID:26217345

  9. Aluminum X-ray mass-ablation rate measurements

    DOE PAGES

    Kline, John L.; Hager, Jonathan D.

    2016-10-15

    Measurements of the mass ablation rate of aluminum (Al) have been completed at the Omega Laser Facility. Measurements of the mass-ablation rate show Al is higher than plastic (CH), comparable to high density carbon (HDC), and lower than beryllium. The mass-ablation rate is consistent with predictions using a 1D Lagrangian code, Helios. Lastly, the results suggest Al capsules have a reasonable ablation pressure even with a higher albedo than beryllium or carbon ablators warranting further investigation into the viability of Al capsules for ignition should be pursued.

  10. Efficacy and safety of Hybrid-APC for the ablation of Barrett's esophagus.

    PubMed

    Manner, Hendrik; May, Andrea; Kouti, Ioanna; Pech, Oliver; Vieth, Michael; Ell, Christian

    2016-04-01

    After thermal ablation of Barrett's esophagus (BE), stricture formation is reported in 5 to over 10% of patients. The question arises whether submucosal fluid injection prior to ablation may lower the risk of stricture formation. The aim of the present study was to evaluate the efficacy and safety of the new technique of Hybrid-APC which combines submucosal injection with APC. Patients who had a residual BE segment of at least 1 cm after endoscopic resection of early Barrett's neoplasia underwent thermal ablation of BE by Hybrid-APC. Prior to thermal ablation, submucosal injection of sodium chloride 0.9% was carried out using a flexible water-jet probe (Erbejet 2; Erbe Elektromedizin, Tuebingen, Germany). Check-up upper GI endoscopy was carried out 3 months after macroscopically complete ablation including biopsies from the neo-Z-line and the former BE segment, and recording of stricture formation. From May 2011 to November 2012, a total of 60 patients (pt) were included in the study [55 pt male (92%); mean age 62 ± 9 years, range 42-79]. Ten patients were excluded from the study. In the remaining 50 pt, Hybrid-APC ablation and check-up endoscopy at 3 months were carried out. Forty-eight out of 50 pt (96%; ITT: 49/60, 82%) achieved macroscopically complete remission after a median of 3.5 APC sessions [SD 2.4; range 1-10]. Freedom from BE was histopathologically observed in 39/50 patients (78%). There was one treatment-related stricture (2%). Minor adverse events of Hybrid-APC were observed in 11 patients (22%). According to this pilot series, Hybrid-APC was effective and safe for BE ablation in a tertiary referral center. The rate of stricture formation was only 2%. Further studies are required to confirm the present results. DRKS00003369.

  11. Analysis of identified iron meteoroids: Possible relation with M-type Earth-crossing asteroids?

    NASA Astrophysics Data System (ADS)

    Revelle, D. O.; Ceplecha, Z.

    1994-12-01

    We have used two different techniques to analyze the U. S. Prairie Network (PN) fireballs in order to search for possible nickel-iron meteoroids. The first approach used is that of ReVelle and Rajan which is similar to the analysis carried out earlier by Wetherill and ReVelle in a series of papers relating first to the chondrites and later to fireballs of cometary origin. The second approach is a new technique developed by Ceplecha and co-workers that can simultaneously determine the presence and location of gross fragmentation events and also determine an effective ablation parameter during the fireball entry. Using this combined approach we have determined that seven fireballs among the 287 that were analyzed are likely to be iron in composition. Using the method of Ceplecha we have determined that none of these objects experienced any gross fragmentation events during their entry to the atmosphere and most of the meteoroids also exhibited rather large ablation coefficients during entry as well, a feature that is also characteristic of the ReVelle and Rajan approach. For all of these objects for which we currently have available data, we have determined that gross fragmentation events did not occur during the entry.

  12. Femtosecond nonlinear optical properties of laser ablated gold nanoparticles in water

    NASA Astrophysics Data System (ADS)

    Krishnakanth, K. N.; Bharathi, M. S. S.; Hamad, S.; Rao, S. Venugopal

    2018-04-01

    Femtosecond third order nonlinear optical (NLO) properties of ultrafast laser ablated gold (Au) colloidsin distilled waterare investigatedusing degenerate four wave mixing technique with 50fs pulses at 800nm wavelength. The estimated value of χ(3) obtained for Au nanoparticles is 1.93×10-14 e.s.u. The characterization of the NPs was achieved done using TEM and HR-TEM techniques. We also present the time resolved studies of Au colloids by using DFWM technique in the forward BOXCAR phase matching geometry.

  13. High-intensity focused ultrasound ablation: an effective and safe treatment for secondary hypersplenism.

    PubMed

    Zhu, J; Zhu, H; Mei, Z; Zhang, L; Jin, C; Ran, L; Zhou, K; Yang, W

    2014-11-01

    Hypersplenism is a common disease. The conventional treatment is splenectomy and partial splenic embolization; however, both of them have high complication rates and technical defects. Therefore, safer and more effective techniques should be considered for the treatment of hypersplenism. High-intensity focused ultrasound (HIFU) may provide an effective and safe way for treatment of hypersplenism. Therefore, we conducted this study to assess the safety and efficacy of HIFU in treatment of secondary hypersplenism. A total of 28 patients who suffered from secondary hypersplenism were treated with HIFU ablation. All patients who underwent HIFU were closely followed-up over a year. MRI scan was performed, and the spleens were observed. Blood counts and liver function tests were also carried out. In the follow-up process, the levels of white blood cells and platelets in the blood after HIFU were significantly higher than those before HIFU, liver function also improved after HIFU treatment. In addition, the symptoms were ameliorated significantly or even disappeared. The MRI showed that the ablation area had turned into a non-perfused volume, and after 12 months of HIFU ablation, the ablated area shrank evidently; the sunken spleen formed a lobulated shape and the splenic volume decreased. HIFU ablation is a safe, effective and non-invasive approach for secondary hypersplenism. For the first time we used HIFU ablation to treat secondary hypersplenism. It not only expands indications of HIFU but also provides better choice for the treatment of secondary hypersplenism.

  14. Comparison of Quadrapolar™ radiofrequency lesions produced by standard versus modified technique: an experimental model.

    PubMed

    Safakish, Ramin

    2017-01-01

    Lower back pain (LBP) is a global public health issue and is associated with substantial financial costs and loss of quality of life. Over the years, different literature has provided different statistics regarding the causes of the back pain. The following statistic is the closest estimation regarding our patient population. The sacroiliac (SI) joint pain is responsible for LBP in 18%-30% of individuals with LBP. Quadrapolar™ radiofrequency ablation, which involves ablation of the nerves of the SI joint using heat, is a commonly used treatment for SI joint pain. However, the standard Quadrapolar radiofrequency procedure is not always effective at ablating all the sensory nerves that cause the pain in the SI joint. One of the major limitations of the standard Quadrapolar radiofrequency procedure is that it produces small lesions of ~4 mm in diameter. Smaller lesions increase the likelihood of failure to ablate all nociceptive input. In this study, we compare the standard Quadrapolar radiofrequency ablation technique to a modified Quadrapolar ablation technique that has produced improved patient outcomes in our clinic. The methodology of the two techniques are compared. In addition, we compare results from an experimental model comparing the lesion sizes produced by the two techniques. Taken together, the findings from this study suggest that the modified Quadrapolar technique provides longer lasting relief for the back pain that is caused by SI joint dysfunction. A randomized controlled clinical trial is the next step required to quantify the difference in symptom relief and quality of life produced by the two techniques.

  15. Particle dynamics during nanoparticle synthesis by laser ablation in a background gas

    NASA Astrophysics Data System (ADS)

    Nakata, Yoshiki; Muramoto, Junichi; Okada, Tatsuo; Maeda, Mitsuo

    2002-02-01

    Particle dynamics during Si nanoparticle synthesis in a laser-ablation plume in different background gases were investigated by laser-spectroscopic imaging techniques. Two-dimensional laser induced fluorescence and ultraviolet Rayleigh scattering techniques were used to visualize the spatial distribution of the Si atoms and nanoparticles grown, respectively. We have developed a visualization technique called re-decomposition laser-induced fluorescence to observe small nanoparticles (hereafter called clusters) which are difficult to observe by the conventional imaging techniques. In this article, the whole process of nanoparticle synthesis in different background gases of He, Ne, Ar, N2 and O2 was investigated by these techniques. In He, Ne, Ar and N2 background gases at 10 Torr, the clustering of the Si atoms started 200, 250, 300 and 800 μs after ablation, respectively. The growth rate of the clusters in He background gas was much larger than that in the other gases. The spatial distributions of the Si nanoparticles were mushroom like in He, N2 and O2, and column like in Ne and Ar. It is thought that the difference in distribution was caused by differences in the flow characteristics of the background gases, which would imply that the viscosity of the background gas is one of the main governing parameters.

  16. Real-time estimation of lesion depth and control of radiofrequency ablation within ex vivo animal tissues using a neural network.

    PubMed

    Wang, Yearnchee Curtis; Chan, Terence Chee-Hung; Sahakian, Alan Varteres

    2018-01-04

    Radiofrequency ablation (RFA), a method of inducing thermal ablation (cell death), is often used to destroy tumours or potentially cancerous tissue. Current techniques for RFA estimation (electrical impedance tomography, Nakagami ultrasound, etc.) require long compute times (≥ 2 s) and measurement devices other than the RFA device. This study aims to determine if a neural network (NN) can estimate ablation lesion depth for control of bipolar RFA using complex electrical impedance - since tissue electrical conductivity varies as a function of tissue temperature - in real time using only the RFA therapy device's electrodes. Three-dimensional, cubic models comprised of beef liver, pork loin or pork belly represented target tissue. Temperature and complex electrical impedance from 72 data generation ablations in pork loin and belly were used for training the NN (403 s on Xeon processor). NN inputs were inquiry depth, starting complex impedance and current complex impedance. Training-validation-test splits were 70%-0%-30% and 80%-10%-10% (overfit test). Once the NN-estimated lesion depth for a margin reached the target lesion depth, RFA was stopped for that margin of tissue. The NN trained to 93% accuracy and an NN-integrated control ablated tissue to within 1.0 mm of the target lesion depth on average. Full 15-mm depth maps were calculated in 0.2 s on a single-core ARMv7 processor. The results show that a NN could make lesion depth estimations in real-time using less in situ devices than current techniques. With the NN-based technique, physicians could deliver quicker and more precise ablation therapy.

  17. Considering Angle Selection When Using Ultrasound Electrode Displacement Elastography to Evaluate Radiofrequency Ablation of Tissues

    PubMed Central

    Li, Qiang; Chen, Pin-Yu; Wang, Chiao-Yin; Liu, Hao-Li; Teng, Jianfu

    2014-01-01

    Percutaneous radiofrequency ablation (RFA) is a minimally invasive treatment to thermally destroy tumors. Ultrasound-based electrode-displacement elastography is an emerging technique for evaluating the region of RFA-induced lesions. The angle between the imaging probe and the RFA electrode can influence electrode-displacement elastography when visualizing the ablation zone. We explored the angle effect on electrode-displacement elastography to measure the ablation zone. Phantoms embedded with meatballs were fabricated and then ablated using an RFA system to simulate RFA-induced lesions. For each phantom, a commercial ultrasound scanner with a 7.5 MHz linear probe was used to acquire raw image data at different angles, ranging from 30° to 90° at increments of 10°, to construct electrode-displacement images and facilitate comparisons with tissue section images. The results revealed that the ablation regions detected using electrode-displacement elastography were highly correlated with those from tissue section images when the angle was between 30° and 60°. However, the boundaries of lesions were difficult to distinguish, when the angle was larger than 60°. The experimental findings suggest that angle selection should be considered to achieve reliable electrode-displacement elastography to describe ablation zones. PMID:24971347

  18. The advent of ultrasound-guided ablation techniques in nodular thyroid disease: towards a patient-tailored approach.

    PubMed

    Papini, Enrico; Pacella, Claudio M; Misischi, Irene; Guglielmi, Rinaldo; Bizzarri, Giancarlo; Døssing, Helle; Hegedus, Laszlo

    2014-08-01

    Surgery is the long-established therapeutic option for benign thyroid nodules, which steadily grow and become symptomatic. The cost of thyroid surgery, the risk of temporary or permanent complications, and the effect on quality of life, however, remain relevant concerns. Therefore, various minimally invasive treatments, directed towards office-based management of symptomatic nodules, without requiring general anaesthesia, and with negligible damage to the skin and cervical tissues, have been proposed during the past two decades. Today, ultrasound-guided percutaneous ethanol injection and thermal ablation with laser or radiofrequency have been thoroughly evaluated, and are accessible procedures in specialized centres. In clinical practice, relapsing thyroid cysts are effectively managed with percutaneous ethanol injection treatment, which should be considered therapy of choice. In solid non-functioning thyroid nodules that grow or become symptomatic, trained operators may safely induce, with a single session of laser ablation treatment or radiofrequency ablation, a 50% volume decrease and, in parallel, improve local symptoms. In contrast, hyperfunctioning nodules remain best treated with radioactive iodine, which results in a better control of hyperthyroidism, also in the long-term, and fewer side-effects. Currently, minimally invasive treatment is also investigated for achieving local control of small size neck recurrences of papillary thyroid carcinoma in patients who are poor candidates for repeat cervical lymph node dissection. This particular use should still be considered experimental. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Comprehensive studies of ultrashort laser pulse ablation of tin target at terawatt power

    NASA Astrophysics Data System (ADS)

    Elsied, Ahmed M.; Diwakar, Prasoon K.; Hassanein, Ahmed

    2018-01-01

    The fundamental properties of ultrashort laser interactions with metals using up to terawatt power were comprehensively studied, i.e., specifically mass ablation, nanoparticle formation, and ion dynamics using multitude of diagnostic techniques. Results of this study can be useful in many fields of research including spectroscopy, micromachining, thin film fabrication, particle acceleration, physics of warm dense matter, and equation-of-state determination. A Ti:Sapphire femtosecond laser system (110 mJ maximum energy, 40 fs, 800 nm, P-polarized, single pulse mode) was used, which delivered up to 3 terawatt laser power to ablate 1 mm tin film in vacuum. The experimental analysis includes the effect of the incident laser fluence on the ablated mass, size of the ablated area, and depth of ablation using white light profilometer. Atomic force microscope was used to measure the emitted particles size distribution at different laser fluence. Faraday cup (FC) detector was used to analyze the emitted ions flux by measuring the velocity, and the total charge of the emitted ions. The study shows that the size of emitted particles follows log-normal distribution with peak shifts depending on incident laser fluence. The size of the ablated particles ranges from 20 to 80 nm. The nanoparticles deposited on the wafer tend to aggregate and to be denser as the incident laser fluence increases as shown by AFM images. Laser ablation depth was found to increase logarithmically with laser fluence then leveling off at laser fluence > 400 J/cm2. The total ablated mass tends to increase logarithmically with laser fluence up to 60 J/cm2 while, increases gradually at higher fluence due to the increase in the ablated area. The measured ion emitted flux shows a linear dependence on laser fluence with two distinct regimes. Strong dependence on laser fluence was observed at fluences < 350 J/cm2. Also, a slight enhancement in ion velocity was observed with increasing laser fluence up to 350 J

  20. Radiofrequency catheter ablation versus balloon cryoablation of atrial fibrillation: markers of myocardial damage, inflammation, and thrombogenesis.

    PubMed

    Antolič, Bor; Pernat, Andrej; Cvijić, Marta; Žižek, David; Jan, Matevž; Šinkovec, Matjaž

    2016-07-01

    Evidence from animal and human studies suggests that cryoablation might be associated with a lesser inflammatory response and activation of coagulation compared with radiofrequency ablation. The study was aimed at comparing the effect of cryoballoon and radiofrequency catheter ablation of paroxysmal atrial fibrillation on markers of myocardial damage, inflammation, and activation of coagulation. Forty-one patients received either cryoballoon (n = 23) or radiofrequency (n = 18) ablation of atrial fibrillation. We measured troponin I, high-sensitivity CRP, and interleukin 6 at baseline from the cubital vein, and from the right and left atrium before and after ablation, and from the cubital vein the following day. Prothrombin fragments 1 + 2, soluble P‑selectin, and D‑dimer were measured before and after ablation from both atria. We observed higher troponin I release in the cryoballoon than in the radiofrequency group (7.01 mcg/l (interquartile range [IQR]: 5.30-9.09) vs 2.32 mcg/l (IQR: 1.45-2.98), p < 0.001). The levels of inflammatory markers (high-sensitivity CRP and interleukin 6) in the two groups were comparable, as were the levels of markers of coagulation activation. Procedure duration, fluoroscopy times, and mid-term success (23 months, IQR 7-32) of the two groups were also comparable. Cryoballoon ablation of atrial fibrillation causes more significant myocardial damage, that is, more extensive ablation lesions, compared with radiofrequency catheter ablation. However, no major differences between these two ablation techniques with regard to the inflammatory response and activation of the coagulation system were observed.

  1. Right atrium positioning for exposure of right pulmonary veins during off-pump atrial fibrillation ablation.

    PubMed

    Suwalski, Grzegorz; Emery, Robert; Mróz, Jakub; Kaczejko, Kamil; Gryszko, Leszek; Cwetsch, Andrzej; Skrobowski, Andrzej

    2017-06-01

    Concomitant surgical ablation of atrial fibrillation (AF) is recommended for patients undergoing off-pump coronary revascularization in the presence of this arrhythmia. Achievement of optimal visualization of pulmonary veins while maintaining stable haemodynamic conditions is crucial for proper completion of the ablation procedure. This study evaluates the safety and feasibility of right atrial positioning using a suction-based cardiac positioner as opposed to compressive manoeuvres for exposure during off-pump surgical ablation for AF. Thirty-four consecutive patients underwent pulmonary vein isolation, ganglionated plexi ablation and left atrial appendage occlusion during off-pump coronary artery bypass grafting. Right atrial suction positioning was used to visualize right pulmonary veins. Safety and feasibility end points were analysed intraoperatively and in the early postoperative course. In all patients, right atrial positioning created optimal conditions to complete transverse and oblique sinus blunt dissection, correct placement of a bipolar ablation probe, detection and ablation of ganglionated plexi and conduction block assessment. In all patients, this entire right-sided ablation procedure was completed with a single exposure manoeuvre. Feasibility end points were achieved in all study patients. This report documents the safety and feasibility of right atrial exposure using a suction-based cardiac positioner to complete ablation for AF concomitant with off-pump coronary revascularization. This technique may be widely adopted to create stable haemodynamic conditions and optimal visualization of the right pulmonary veins. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  2. Ablation of hypertrophic septum using radiofrequency energy: an alternative for gradient reduction in patient with hypertrophic obstructive cardiomyopathy?

    PubMed

    Riedlbauchová, Lucie; Janoušek, Jan; Veselka, Josef

    2013-06-01

    Alcohol septal ablation and surgical myectomy represent accepted therapeutic options for treatment of symptomatic patients with hypertrophic obstructive cardiomyopathy. Long-term experience with radiofrequency ablation of arrhythmogenic substrates raised a question if this technique might be effective for left ventricular outflow tract (LVOT) gradient reduction. We report on a 63-year-old patient with recurrence of symptoms 1 year after alcohol septal ablation (ASA) leading originally to a significant reduction of both symptoms and gradient. Due to a new increase of gradient in the LVOT up to 200 mm Hg with corresponding worsening of symptoms and due to refusal of surgical myectomy by the patient, endocardial radiofrequency ablation of the septal hypertrophy (ERASH) was indicated. Radiofrequency ablation was performed in the LVOT using irrigated-tip ablation catheter; the target site was identified using intracardiac echocardiography and electroanatomical CARTO mapping. ERASH caused an immediate gradient reduction due to hypokinesis of the ablated septum. At 2-month follow-up exam, significant clinical improvement was observed, together with persistent gradient reduction assessed with Doppler echocardiography. Echocardiography and magnetic resonance revealed persistent septal hypokinesis and slight thinning of the ablated region. Septal ablation using radiofrequency energy may be a promising alternative or adjunct to the treatment of hypertrophic obstructive cardiomyopathy. Intracardiac echocardiography and electroanatomical CARTO mapping enable exact lesion placement and preservation of atrioventricular conduction.

  3. The effect of laser ablation parameters on optical limiting properties of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Gursoy, Irmak; Yaglioglu, Halime Gul

    2017-09-01

    This paper presents the effect of laser ablation parameters on optical limiting properties of silver nanoparticles. The current applications of lasers such as range finding, guidance, detection, illumination and designation have increased the potential of damaging optical imaging systems or eyes temporary or permanently. The applications of lasers introduce risks for sensors or eyes, when laser power is higher than damage threshold of the detection system. There are some ways to protect these systems such as neutral density (nd) filters, shutters, etc. However, these limiters reduce the total amount of light that gets into the system. Also, response time of these limiters may not be fast enough to prevent damage and cause precipitation in performance due to deprivation of transmission or contrast. Therefore, optical limiting filters are needed that is transparent for low laser intensities and limit or block the high laser intensities. Metal nanoparticles are good candidates for such optical limiting filters for ns pulsed lasers or CW lasers due to their high damage thresholds. In this study we investigated the optical limiting performances of silver nanoparticles produced by laser ablation technique. A high purity silver target immersed in pure water was ablated with a Nd:YAG nanosecond laser at 532 nm. The effect of altering laser power and ablation time on laser ablation efficiency of nanoparticles was investigated experimentally and optimum values were specified. Open aperture Zscan experiment was used to investigate the effect of laser ablation parameters on the optical limiting performances of silver nanoparticles in pure water. It was found that longer ablation time decreases the optical limiting threshold. These results are useful for silver nanoparticles solutions to obtain high performance optical limiters.

  4. Magnetic Resonance Mediated Radiofrequency Ablation.

    PubMed

    Hue, Yik-Kiong; Guimaraes, Alexander R; Cohen, Ouri; Nevo, Erez; Roth, Abraham; Ackerman, Jerome L

    2018-02-01

    To introduce magnetic resonance mediated radiofrequency ablation (MR-RFA), in which the MRI scanner uniquely serves both diagnostic and therapeutic roles. In MR-RFA scanner-induced RF heating is channeled to the ablation site via a Larmor frequency RF pickup device and needle system, and controlled via the pulse sequence. MR-RFA was evaluated with simulation of electric and magnetic fields to predict the increase in local specific-absorption-rate (SAR). Temperature-time profiles were measured for different configurations of the device in agar phantoms and ex vivo bovine liver in a 1.5 T scanner. Temperature rise in MR-RFA was imaged using the proton resonance frequency method validated with fiber-optic thermometry. MR-RFA was performed on the livers of two healthy live pigs. Simulations indicated a near tenfold increase in SAR at the RFA needle tip. Temperature-time profiles depended significantly on the physical parameters of the device although both configurations tested yielded temperature increases sufficient for ablation. Resected livers from live ablations exhibited clear thermal lesions. MR-RFA holds potential for integrating RF ablation tumor therapy with MRI scanning. MR-RFA may add value to MRI with the addition of a potentially disposable ablation device, while retaining MRI's ability to provide real time procedure guidance and measurement of tissue temperature, perfusion, and coagulation.

  5. Micrometeoroid ablation simulated in the laboratory

    NASA Astrophysics Data System (ADS)

    Sternovsky, Zoltan; Thomas, Evan W.; DeLuca, Michael; Horanyi, Mihaly; Janches, Diego; Munsat, Tobin L.; Plane, John M. C.

    2016-04-01

    A facility is developed to simulate the ablation of micrometeoroids in laboratory conditions, which also allows measuring the ionization probability of the ablated material. An electrostatic dust accelerator is used to generate iron and meteoric analog particles with velocities 10-50 km/s. The particles are then introduced into a cell filled with nitrogen, air or carbon dioxide gas with pressures adjustable in the 0.02 - 0.5 Torr range, where the partial or complete ablation of the particle occurs over a short distance. An array of biased electrodes is used to collect the ionized products with spatial resolution along the ablating particles' path, allowing thus the study of the temporal resolution of the process. A simple ablation model is used to match the observations. For completely ablated particles the total collected charge directly yields the ionization efficiency for. The measurements using iron particles in N2 and air are in relatively good agreement with earlier data. The measurements with CO2 and He gases, however, are significantly different from the expectations.

  6. Fluorescent carbon and graphene oxide nanoparticles synthesized by the laser ablation in liquid

    NASA Astrophysics Data System (ADS)

    Małolepszy, A.; Błonski, S.; Chrzanowska-Giżyńska, J.; Wojasiński, M.; Płocinski, T.; Stobinski, L.; Szymanski, Z.

    2018-04-01

    The results of synthesis of the fluorescent carbon dots (CDots) from graphite target and reduced graphene oxide (rGO) nanoparticles performed by the nanosecond laser ablation in polyethylene glycol 200 (PEG200) are shown. Two-step laser irradiation (first graphite target, next achieved suspension) revealed a very effective production of CDots. However, the ablation in PEG appeared to be effective with 1064 nm laser pulse in contrast to the ablation with 355 nm laser pulse. In the case of rGO nanoparticles similar laser irradiation procedure was less efficient. In both cases, received nanoparticles exhibited strong, broadband photoluminescence with a maximum dependent on the excitation wavelength. The size distribution for obtained CDots was evaluated using the DLS technique and HRTEM images. The results from both methods show quite good agreement in nanoparticle size estimation although the DLS method slightly overestimates nanoparticle's diameter.

  7. Clinical impact of rotor ablation in atrial fibrillation: a systematic review.

    PubMed

    Parameswaran, Ramanathan; Voskoboinik, Aleksandr; Gorelik, Alexandra; Lee, Geoffrey; Kistler, Peter M; Sanders, Prashanthan; Kalman, Jonathan M

    2018-01-11

    Rotor mapping and ablation have gained favour over the recent years as an emerging ablation strategy targeting drivers of atrial fibrillation (AF). Their efficacy, however, has been a topic of great debate with variable outcomes across centres. The aim of this study was to systematically review the recent medical literature to determine the medium-term outcomes of rotor ablation in patients with paroxysmal atrial fibrillation (PAF) and persistent atrial fibrillation (PeAF). A systematic search of the contemporary scientific literature (PubMed and EMBASE) was performed in August 2017. Only studies assessing arrhythmia-free survival from rotor ablation of AF were included. We used the random-effects model to assess the primary outcome of pooled medium-term single-procedure AF-free survival for both PAF and PeAF. Success rates from multiple procedures and complication rates were also examined. We included 11 observational studies (4 PAF and 10 PeAF) with a total of 556 patients (166 PAF and 390 PeAF). Pooled single-procedure freedom from AF was 37.8% [95% confidence interval 5.6-86.3%] at a mean follow-up period of 13.8 ± 1.8 months for PAF and 59.2% (95% CI 41.4-74.9%) at a mean follow-up period of 12.9 ± 6 months for PeAF. There was a marked heterogeneity between studies (I2 = 93.8% for PAF and 88.3% for PeAF). The mean complication rate of rotor ablation among the reported studies was 3.4%. The wide variability in success rate between different centres performing rotor ablations suggests that the optimal ablation strategy, particularly targeting rotors, is unclear. Results from randomized studies are necessary before this technique can be considered as an established clinical tool. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.

  8. The Femtosecond Laser Ablation on Ultrafine-Grained Copper

    NASA Astrophysics Data System (ADS)

    Lu, Jianxun; Wu, Xiaoyu; Ruan, Shuangchen; Guo, Dengji; Du, Chenlin; Liang, Xiong; Wu, Zhaozhi

    2018-07-01

    To investigate the effects of femtosecond laser ablation on the surface morphology and microstructure of ultrafine-grained copper, point, single-line scanning, and area scanning ablation of ultrafine-grained and coarse-grained copper were performed at room temperature. The ablation threshold gradually increased and materials processing became more difficult with decreasing grain size. In addition, the ablation depth and width of the channels formed by single-line scanning ablation gradually increased with increasing grain size for the same laser pulse energy. The microhardness of the ablated specimens was also evaluated as a function of laser pulse energy using area scanning ablation. The microhardness difference before and after ablation increased with decreasing grain size for the same laser pulse energy. In addition, the microhardness after ablation gradually decreased with increasing laser pulse energy for the ultrafine-grained specimens. However, for the coarse-grained copper specimens, no clear changes of the microhardness were observed after ablation with varying laser pulse energies. The grain sizes of the ultrafine-grained specimens were also surveyed as a function of laser pulse energy using electron backscattered diffraction (EBSD). The heat generated by laser ablation caused recrystallization and grain growth of the ultrafine-grained copper; moreover, the grain size gradually increased with increasing pulse energy. In contrast, no obvious changes in grain size were observed for the coarse-grained copper specimens with increasing pulse energy.

  9. The Femtosecond Laser Ablation on Ultrafine-Grained Copper

    NASA Astrophysics Data System (ADS)

    Lu, Jianxun; Wu, Xiaoyu; Ruan, Shuangchen; Guo, Dengji; Du, Chenlin; Liang, Xiong; Wu, Zhaozhi

    2018-05-01

    To investigate the effects of femtosecond laser ablation on the surface morphology and microstructure of ultrafine-grained copper, point, single-line scanning, and area scanning ablation of ultrafine-grained and coarse-grained copper were performed at room temperature. The ablation threshold gradually increased and materials processing became more difficult with decreasing grain size. In addition, the ablation depth and width of the channels formed by single-line scanning ablation gradually increased with increasing grain size for the same laser pulse energy. The microhardness of the ablated specimens was also evaluated as a function of laser pulse energy using area scanning ablation. The microhardness difference before and after ablation increased with decreasing grain size for the same laser pulse energy. In addition, the microhardness after ablation gradually decreased with increasing laser pulse energy for the ultrafine-grained specimens. However, for the coarse-grained copper specimens, no clear changes of the microhardness were observed after ablation with varying laser pulse energies. The grain sizes of the ultrafine-grained specimens were also surveyed as a function of laser pulse energy using electron backscattered diffraction (EBSD). The heat generated by laser ablation caused recrystallization and grain growth of the ultrafine-grained copper; moreover, the grain size gradually increased with increasing pulse energy. In contrast, no obvious changes in grain size were observed for the coarse-grained copper specimens with increasing pulse energy.

  10. Microwave ablation for thyroid nodules: a new string to the bow for percutaneous treatments?

    PubMed Central

    Morelli, Francesco; Sacrini, Andrea; Pompili, Giovanni; Borelli, Anna; Panella, Silvia; Masu, Annamaria; De Pasquale, Loredana; Giacchero, Roberta

    2016-01-01

    Background Thyroid nodules are a fairly common finding in general population and, even if most of them are benign, a treatment can be however necessary. In the last years, non surgical minimally invasive techniques have been developed to treat this pathology, starting from percutaneous ethanol injection (PEI), to laser ablation (LA), radiofrequency ablation (RFA) and, most recently, microwave ablation (MWA). Methods We reviewed all medical literature searching in pubmed.gov the terms “microwave” & “thyroid”. We found three original studies concerning MWA treatment, for a total of 263 patients (mean age 51.0 years; range, 15–80 years; male to female ratio 2.55) and 522 nodules. Results A total of 522 nodules (338 solid, 22 cystic, 162 mixed) in 263 patients were treated. Studies have shown a mean reduction in volume of thyroid nodules ranging from 45.9% to 65%. No study reported a significant and definitive change in laboratory parameters, except for one case (Heck et al.). No studies have reported major complications after procedure. Conclusions MWA is a new, promising technique among the minimally invasive treatments of thyroid nodules. Actually, the larger diameter of MW antenna seems to be the major limiting factor in the use of this technique. More studies are necessary to evaluate feasibility, safety and efficacy of the procedure. PMID:28149799

  11. Multiple target laser ablation system

    DOEpatents

    Mashburn, D.N.

    1996-01-09

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film. 3 figs.

  12. Multiple target laser ablation system

    DOEpatents

    Mashburn, Douglas N.

    1996-01-01

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film.

  13. Clinical Implications of Ablation of Drivers for Atrial Fibrillation: A Systematic Review and Meta-Analysis.

    PubMed

    Baykaner, Tina; Rogers, Albert J; Meckler, Gabriela L; Zaman, Junaid; Navara, Rachita; Rodrigo, Miguel; Alhusseini, Mahmood; Kowalewski, Christopher A B; Viswanathan, Mohan N; Narayan, Sanjiv M; Clopton, Paul; Wang, Paul J; Heidenreich, Paul A

    2018-05-01

    The outcomes from pulmonary vein isolation (PVI) for atrial fibrillation (AF) are suboptimal, but the benefits of additional lesion sets remain unproven. Recent studies propose ablation of AF drivers improves outcomes over PVI, yet with conflicting reports in the literature. We undertook a systematic literature review and meta-analysis to determine outcomes from ablation of AF drivers in addition to PVI or as a stand-alone procedure. Database search was done using the terms atrial fibrillation and ablation or catheter ablation and driver or rotor or focal impulse or FIRM (Focal Impulse and Rotor Modulation). We pooled data using random effects model and assessed heterogeneity with I 2 statistic. Seventeen studies met inclusion criteria, in a cohort size of 3294 patients. Adding AF driver ablation to PVI reported freedom from AF of 72.5% (confidence interval [CI], 62.1%-81.8%; P <0.01) and from all arrhythmias of 57.8% (CI, 47.5%-67.7%; P <0.01). AF driver ablation when added to PVI or as stand-alone procedure compared with controls produced an odds ratio of 3.1 (CI, 1.3-7.7; P =0.02) for freedom from AF and an odds ratio of 1.8 (CI, 1.2-2.7; P <0.01) for freedom from all arrhythmias in 4 controlled studies. AF termination rate was 40.5% (CI, 30.6%-50.9%) and predicted favorable outcome from ablation( P <0.05). In controlled studies, the addition of AF driver ablation to PVI supports the possible benefit of a combined approach of AF driver ablation and PVI in improving single-procedure freedom from all arrhythmias. However, most studies are uncontrolled and are limited by substantial heterogeneity in outcomes. Large multicenter randomized trials are needed to precisely define the benefits of adding driver ablation to PVI. © 2018 American Heart Association, Inc.

  14. Facile and fast synthesis of SnS2 nanoparticles by pulsed laser ablation in liquid

    NASA Astrophysics Data System (ADS)

    Johny, J.; Sepulveda-Guzman, S.; Krishnan, B.; Avellaneda, D.; Shaji, S.

    2018-03-01

    Nanoparticles (NPs) of tin disulfide (SnS2) were synthesized using pulsed laser ablation in liquid (PLAL) technique. Effects of different liquid media and ablation wavelengths on the morphology and optical properties of the nanoparticles were studied. Nd: YAG laser wavelengths of 532 nm and 1064 nm (frequency 10 Hz and pulse width 10 ns) were used to irradiate SnS2 target immersed in liquid for the synthesis of SnS2 nanoparticles. Here PLAL was a fast synthesis technique, the ablation was only for 30 s. Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-vis absorption spectroscopy and photoluminescence spectroscopy were used to characterize the SnS2 NPs. TEM images showed that the liquid medium and laser wavelength influence the morphology of the NPs. SAED patterns and high resolution TEM (HRTEM) images confirmed the crystallinity of the particles. XRD and XPS analyses confirmed that SnS2 NPs were having exact crystalline structure and chemical states as that of the target. Raman analysis also supported the results obtained by XRD and XPS. Optical band gaps of the nanocolloids evaluated from their UV-vis absorption spectra were 2.4-3.05 eV. SnS2 NPs were having luminescence spectra in the blue-green region irrespective of the liquid media and ablation wavelength.

  15. Short communication. Development of a fine thermocouple-needle system for real-time feedback of thermal tumour ablation margin.

    PubMed

    Ishizaka, H; Shiraishi, A; Awata, S; Shimizu, A; Hirasawa, S

    2011-12-01

    Thermal tumour ablation techniques such as radiofrequency (RF) ablation are applied for radical removal of local tumours as an easier, less invasive alternative to surgical resection. A serious drawback of thermal ablation, however, is that the ablation area cannot be accurately assessed during the procedure. To achieve real-time feedback and exact and safe ablation, a superfine thermocouple-needle system (TNS) comprising a 0.25-mm diameter thermocouple embedded in a 22-G, 15-cm-long needle was devised and efficacy was tested in vitro using porcine livers (n = 15) and in vivo using rabbit back muscles (n = 2) and livers (n = 3). A 17-gauge RF electrode with a 2 cm active tip was used for ablation. The TNS was inserted 1 cm from the active tip of the RF electrode and liver temperature around the electrode was measured concurrently. The RF current was cut off when the temperature reached 60°C or after 5 min at ≥50°C. Porcine livers and rabbit back muscles were then cut along a plane passing through the axes of the electrode and the TNS. In rabbit livers, contrast-enhanced CT was performed to evaluate ablation areas. Ablation areas in cut surfaces of porcine livers exhibited well-defined discoloured regions and the TNS tip precisely pinpointed the margin of the ablation area. Contrast-enhanced CT of rabbit livers showed the TNS tip accurately located at the margin of areas without contrast enhancement. These results indicate that the TNS can accurately show ablation margins and that placing the TNS tip at the intended ablation margin permits exact thermal ablation.

  16. Rotor mapping and ablation to treat atrial fibrillation

    PubMed Central

    Zaman, Junaid A.B.; Peters, Nicholas S.; Narayan, Sanjiv M.

    2015-01-01

    Purpose of review Rotors have long been postulated to drive atrial fibrillation, but evidence has been limited to animal models. This changed recently with the demonstration using focal impulse and rotor modulation (FIRM) mapping that rotors act as human atrial fibrillation sources. This mechanistic approach to diagnosing the causes of atrial fibrillation in individual patients has been supported by substantially improved outcomes from FIRM-guided ablation, resulting in increased attention to rotors as therapeutic targets. Recent findings In this review, we outline the pathophysiology of rotors in animal and in-silico studies of fibrillation, and how this motivated FIRM mapping in humans. We highlight the characteristics of rotors in human atrial fibrillation, now validated by several techniques, with discussion on similar and discrepant findings between techniques. The interventional approaches to eliminate atrial fibrillation rotors are explained and the ablation results in latest studies using FIRM are discussed. Summary We propose that mapping localized sources for human atrial fibrillation, specifically rotors, is moving the field towards a unifying hypothesis that explains several otherwise contradictory observations in atrial fibrillation management. We conclude by suggesting areas of potential research that may reveal more about these critical sites and how these may lead to better and novel treatments for atrial fibrillation. PMID:25389649

  17. Percutaneous Radiofrequency Ablation of a Small Renal Mass Complicated by Appendiceal Perforation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boone, Judith, E-mail: j.boone@amc.uva.nl; Bex, Axel, E-mail: a.bex@nki.nl; Prevoo, Warner, E-mail: w.prevoo@nki.nl

    2012-06-15

    Percutaneous radiofrequency ablation (RFA) has gained wide acceptance as nephron-sparing therapy for small renal masses in select patients. Generally, it is a safe procedure with minor morbidity and acceptable short-term oncologic outcome. However, as a result of the close proximity of vital structures, such as the bowel, ureter, and large vessels, to the ablative field, complications regarding these structures may occur. This is the first article describing appendiceal perforation as a complication of computed tomography-guided RFA despite hydrodissection. When performing this innovative and promising procedure one should be aware of the possibility of particular minor and even major complications.

  18. Influence and measurement of mass ablation in ICF implosions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Spears, B K; Hicks, D; Velsko, C

    2007-09-05

    Point design ignition capsules designed for the National Ignition Facility (NIF) currently use an x-ray-driven Be(Cu) ablator to compress the DT fuel. Ignition specifications require that the mass of unablated Be(Cu), called residual mass, be known to within 1% of the initial ablator mass when the fuel reaches peak velocity. The specifications also require that the implosion bang time, a surrogate measurement for implosion velocity, be known to +/- 50 ps RMS. These specifications guard against several capsule failure modes associated with low implosion velocity or low residual mass. Experiments designed to measure and to tune experimentally the amount ofmore » residual mass are being developed as part of the National Ignition Campaign (NIC). Tuning adjustments of the residual mass and peak velocity can be achieved using capsule and laser parameters. We currently plan to measure the residual mass using streaked radiographic imaging of surrogate tuning capsules. Alternative techniques to measure residual mass using activated Cu debris collection and proton spectrometry have also been developed. These developing techniques, together with bang time measurements, will allow us to tune ignition capsules to meet NIC specs.« less

  19. Strontium isotope ratios (87Sr/86Sr) of tooth enamel: a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods.

    PubMed

    Copeland, Sandi R; Sponheimer, Matt; le Roux, Petrus J; Grimes, Vaughan; Lee-Thorp, Julia A; de Ruiter, Darryl J; Richards, Michael P

    2008-10-01

    Strontium isotope ratios (87Sr/86Sr) in tooth enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring tooth enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-tooth samples and small and/or rare specimens such as micromammal and fossil teeth.

  20. Nonthermal ablation with microbubble-enhanced focused ultrasound close to the optic tract without affecting nerve function.

    PubMed

    McDannold, Nathan; Zhang, Yong-Zhi; Power, Chanikarn; Jolesz, Ferenc; Vykhodtseva, Natalia

    2013-11-01

    Tumors at the skull base are challenging for both resection and radiosurgery given the presence of critical adjacent structures, such as cranial nerves, blood vessels, and brainstem. Magnetic resonance imaging-guided thermal ablation via laser or other methods has been evaluated as a minimally invasive alternative to these techniques in the brain. Focused ultrasound (FUS) offers a noninvasive method of thermal ablation; however, skull heating limits currently available technology to ablation at regions distant from the skull bone. Here, the authors evaluated a method that circumvents this problem by combining the FUS exposures with injected microbubble-based ultrasound contrast agent. These microbubbles concentrate the ultrasound-induced effects on the vasculature, enabling an ablation method that does not cause significant heating of the brain or skull. In 29 rats, a 525-kHz FUS transducer was used to ablate tissue structures at the skull base that were centered on or adjacent to the optic tract or chiasm. Low-intensity, low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes after intravenous injection of an ultrasound contrast agent (Definity, Lantheus Medical Imaging Inc.). Using histological analysis and visual evoked potential (VEP) measurements, the authors determined whether structural or functional damage was induced in the optic tract or chiasm. Overall, while the sonications produced a well-defined lesion in the gray matter targets, the adjacent tract and chiasm had comparatively little or no damage. No significant changes (p > 0.05) were found in the magnitude or latency of the VEP recordings, either immediately after sonication or at later times up to 4 weeks after sonication, and no delayed effects were evident in the histological features of the optic nerve and retina. This technique, which selectively targets the intravascular microbubbles, appears to be a promising method of noninvasively producing sharply demarcated lesions in

  1. Nonthermal ablation with microbubble-enhanced focused ultrasound close to the optic tract without affecting nerve function

    PubMed Central

    McDannold, Nathan; Zhang, Yong-Zhi; Power, Chanikarn; Jolesz, Ferenc; Vykhodtseva, Natalia

    2014-01-01

    Object Tumors at the skull base are challenging for both resection and radiosurgery given the presence of critical adjacent structures, such as cranial nerves, blood vessels, and brainstem. Magnetic resonance imaging–guided thermal ablation via laser or other methods has been evaluated as a minimally invasive alternative to these techniques in the brain. Focused ultrasound (FUS) offers a noninvasive method of thermal ablation; however, skull heating limits currently available technology to ablation at regions distant from the skull bone. Here, the authors evaluated a method that circumvents this problem by combining the FUS exposures with injected microbubble-based ultrasound contrast agent. These microbubbles concentrate the ultrasound-induced effects on the vasculature, enabling an ablation method that does not cause significant heating of the brain or skull. Methods In 29 rats, a 525-kHz FUS transducer was used to ablate tissue structures at the skull base that were centered on or adjacent to the optic tract or chiasm. Low-intensity, low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes after intravenous injection of an ultrasound contrast agent (Definity, Lantheus Medical Imaging Inc.). Using histological analysis and visual evoked potential (VEP) measurements, the authors determined whether structural or functional damage was induced in the optic tract or chiasm. Results Overall, while the sonications produced a well-defined lesion in the gray matter targets, the adjacent tract and chiasm had comparatively little or no damage. No significant changes (p > 0.05) were found in the magnitude or latency of the VEP recordings, either immediately after sonication or at later times up to 4 weeks after sonication, and no delayed effects were evident in the histological features of the optic nerve and retina. Conclusions This technique, which selectively targets the intravascular microbubbles, appears to be a promising method of noninvasively

  2. Spatially resolved δ13C analysis using laser ablation isotope ratio mass spectrometry

    NASA Astrophysics Data System (ADS)

    Moran, J.; Riha, K. M.; Nims, M. K.; Linley, T. J.; Hess, N. J.; Nico, P. S.

    2014-12-01

    Inherent geochemical, organic matter, and microbial heterogeneity over small spatial scales can complicate studies of carbon dynamics through soils. Stable isotope analysis has a strong history of helping track substrate turnover, delineate rhizosphere activity zones, and identifying transitions in vegetation cover, but most traditional isotope approaches are limited in spatial resolution by a combination of physical separation techniques (manual dissection) and IRMS instrument sensitivity. We coupled laser ablation sampling with isotope measurement via IRMS to enable spatially resolved analysis over solid surfaces. Once a targeted sample region is ablated the resulting particulates are entrained in a helium carrier gas and passed through a combustion reactor where carbon is converted to CO2. Cyrotrapping of the resulting CO2 enables a reduction in carrier gas flow which improves overall measurement sensitivity versus traditional, high flow sample introduction. Currently we are performing sample analysis at 50 μm resolution, require 65 ng C per analysis, and achieve measurement precision consistent with other continuous flow techniques. We will discuss applications of the laser ablation IRMS (LA-IRMS) system to microbial communities and fish ecology studies to demonstrate the merits of this technique and how similar analytical approaches can be transitioned to soil systems. Preliminary efforts at analyzing soil samples will be used to highlight strengths and limitations of the LA-IRMS approach, paying particular attention to sample preparation requirements, spatial resolution, sample analysis time, and the types of questions most conducive to analysis via LA-IRMS.

  3. Burn, freeze, or photo-ablate?: comparative symptom profile in Barrett's dysplasia patients undergoing endoscopic ablation

    NASA Astrophysics Data System (ADS)

    Gill, Kanwar Rupinder S.; Gross, Seth A.; Greenwald, Bruce D.; Hemminger, Lois L.; Wolfsen, Herbert C.

    2009-06-01

    Background: There are few data available comparing endoscopic ablation methods for Barrett's esophagus with high-grade dysplasia (BE-HGD). Objective: To determine differences in symptoms and complications associated with endoscopic ablation. Design: Prospective observational study. Setting: Two tertiary care centers in USA. Patients: Consecutive patients with BE-HGD Interventions: In this pilot study, symptoms profile data were collected for BE-HGD patients among 3 endoscopic ablation methods: porfimer sodium photodynamic therapy, radiofrequency ablation and low-pressure liquid nitrogen spray cryotherapy. Main Outcome Measurements: Symptom profiles and complications from the procedures were assessed 1-8 weeks after treatment. Results: Ten BE-HGD patients were treated with each ablation modality (30 patients total; 25 men, median age: 69 years (range 53-81). All procedures were performed in the clinic setting and none required subsequent hospitalization. The most common symptoms among all therapies were chest pain, dysphagia and odynophagia. More patients (n=8) in the porfimer sodium photodynamic therapy group reported weight loss compared to radio-frequency ablactation (n=2) and cryotherapy (n=0). Four patients in the porfimer sodium photodynamic therapy group developed phototoxicity requiring medical treatment. Strictures, each requiring a single dilation, were found in radiofrequency ablactation (n=1) and porfimer sodium photodynamic therapy (n=2) patients. Limitations: Small sample size, non-randomized study. Conclusions: These three endoscopic therapies are associated with different types and severity of post-ablation symptoms and complications.

  4. Enhanced Radiofrequency Ablation With Magnetically Directed Metallic Nanoparticles.

    PubMed

    Nguyen, Duy T; Tzou, Wendy S; Zheng, Lijun; Barham, Waseem; Schuller, Joseph L; Shillinglaw, Benjamin; Quaife, Robert A; Sauer, William H

    2016-05-01

    Remote heating of metal located near a radiofrequency ablation source has been previously demonstrated. Therefore, ablation of cardiac tissue treated with metallic nanoparticles may improve local radiofrequency heating and lead to larger ablation lesions. We sought to evaluate the effect of magnetic nanoparticles on tissue sensitivity to radiofrequency energy. Ablation was performed using an ablation catheter positioned with 10 g of force over prepared ex vivo specimens. Tissue temperatures were measured and lesion volumes were acquired. An in vivo porcine thigh model was used to study systemically delivered magnetically guided iron oxide (FeO) nanoparticles during radiofrequency application. Magnetic resonance imaging and histological staining of ablated tissue were subsequently performed as a part of ablation lesion analysis. Ablation of ex vivo myocardial tissue treated with metallic nanoparticles resulted in significantly larger lesions with greater impedance changes and evidence of increased thermal conductivity within the tissue. Magnet-guided localization of FeO nanoparticles within porcine thigh preps was demonstrated by magnetic resonance imaging and iron staining. Irrigated ablation in the regions with greater FeO, after FeO infusion and magnetic guidance, created larger lesions without a greater incidence of steam pops. Metal nanoparticle infiltration resulted in significantly larger ablation lesions with altered electric and thermal conductivity. In vivo magnetic guidance of FeO nanoparticles allowed for facilitated radiofrequency ablation without direct infiltration into the targeted tissue. Further research is needed to assess the clinical applicability of this ablation strategy using metallic nanoparticles for the treatment of cardiac arrhythmias. © 2016 American Heart Association, Inc.

  5. History and Technical Approaches and Considerations for Ablative Surgery for Epilepsy.

    PubMed

    Sinha, Saurabh; Danish, Shabbar F

    2016-01-01

    The history of epilepsy surgery is generally noted to have begun in 1886 with Victor Horsley's first report of craniotomies for posttraumatic epilepsy. With increased understanding of brain function and development of electroencephalographic methods, nonlesional epilepsy began to be treated with resection in the 1950s. Methodological improvements and increased understanding of pathophysiology followed, and the advent of stereotaxy and ablative technology in the 1960s and 1970s heralded a new era of minimally invasive, targeted procedures for lesional and nonlesional epilepsy. Current techniques combine stereotactic methods, improved ablative technologies, and electroencephalographic methods for a multidisciplinary approach to the neurosurgical treatment of epilepsy. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Rare complications after lung percutaneous radiofrequency ablation: Incidence, risk factors, prevention and management.

    PubMed

    Alberti, Nicolas; Buy, Xavier; Frulio, Nora; Montaudon, Michel; Canella, Mathieu; Gangi, Afshin; Crombe, Amandine; Palussière, Jean

    2016-06-01

    Among image-guided thermo-ablative techniques, percutaneous radiofrequency ablation (PRFA) is the most widely used technique for the treatment of primary and secondary lung malignancies. Tolerance of PRFA in the lung is excellent. However, relatively little is known about potential rare complications. This article presents both the clinical and imaging features of lung PRFA complications as well as their prevention and management. Complications may be classified in four groups: pleuropulmonary (e.g., bronchopleural or bronchial fistula, delayed abscess or aspergilloma inside post-PRFA cavitations, pulmonary artery pseudo aneurysm, gas embolism and interstitial pneumonia); thoracic wall and vertebral (e.g., rib or vertebral fractures and intercostal artery injury); mediastinal and apical (e.g., neural damage); or diaphragmatic. Most complications can be managed with conservative treatment, percutaneous or endoscopic drainage, or surgical repair. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Patterned femtosecond-laser ablation of Xenopus laevis melanocytes for studies of cell migration, wound repair, and developmental processes

    PubMed Central

    Mondia, Jessica P.; Adams, Dany S.; Orendorff, Ryan D.; Levin, Michael; Omenetto, Fiorenzo G.

    2011-01-01

    Ultrafast (femtosecond) lasers have become an important tool to investigate biological phenomena because of their ability to effect highly localized tissue removal in surgical applications. Here we describe programmable, microscale, femtosecond-laser ablation of melanocytes found on Xenopus laevis tadpoles, a technique that is applicable to biological studies in development, regeneration, and cancer research. We illustrate laser marking of individual melanocytes, and the drawing of patterns on melanocyte clusters to help track their migration and/or regeneration. We also demonstrate that this system can upgrade scratch tests, a technique used widely with cultured cells to study cell migration and wound healing, to the more realistic in vivo realm, by clearing a region of melanocytes and monitoring their return over time. In addition, we show how melanocyte ablation can be used for loss-of-function experiments by damaging neighboring tissue, using the example of abnormal tail regeneration following localized spinal cord damage. Since the size, shape, and depth of melanocytes vary as a function of tadpole age and melanocyte location (head or tail), an ablation threshold chart is given. Mechanisms of laser ablation are also discussed. PMID:21833375

  8. Patterned femtosecond-laser ablation of Xenopus laevis melanocytes for studies of cell migration, wound repair, and developmental processes.

    PubMed

    Mondia, Jessica P; Adams, Dany S; Orendorff, Ryan D; Levin, Michael; Omenetto, Fiorenzo G

    2011-08-01

    Ultrafast (femtosecond) lasers have become an important tool to investigate biological phenomena because of their ability to effect highly localized tissue removal in surgical applications. Here we describe programmable, microscale, femtosecond-laser ablation of melanocytes found on Xenopus laevis tadpoles, a technique that is applicable to biological studies in development, regeneration, and cancer research. We illustrate laser marking of individual melanocytes, and the drawing of patterns on melanocyte clusters to help track their migration and/or regeneration. We also demonstrate that this system can upgrade scratch tests, a technique used widely with cultured cells to study cell migration and wound healing, to the more realistic in vivo realm, by clearing a region of melanocytes and monitoring their return over time. In addition, we show how melanocyte ablation can be used for loss-of-function experiments by damaging neighboring tissue, using the example of abnormal tail regeneration following localized spinal cord damage. Since the size, shape, and depth of melanocytes vary as a function of tadpole age and melanocyte location (head or tail), an ablation threshold chart is given. Mechanisms of laser ablation are also discussed.

  9. Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Phillips, Mark C.; Brumfield, Brian E.; LaHaye, Nicole

    Here, we demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from 235U and 238U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals. The rapid, non-contact measurement is promising for in-field, standoff measurements of uranium enrichment for nuclear safety and security.

  10. Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Phillips, Mark C.; Brumfield, Brian E.; LaHaye, Nicole L.

    We demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from 235U and 238U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals. The rapid, non-contact measurement is promising for in-field, standoff measurements of uranium enrichment for nuclear safety and security applications.

  11. Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes

    DOE PAGES

    Phillips, Mark C.; Brumfield, Brian E.; LaHaye, Nicole; ...

    2017-06-19

    Here, we demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from 235U and 238U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals. The rapid, non-contact measurement is promising for in-field, standoff measurements of uranium enrichment for nuclear safety and security.

  12. Thermal protection during percutaneous thermal ablation procedures: interest of carbon dioxide dissection and temperature monitoring.

    PubMed

    Buy, Xavier; Tok, Chung-Hong; Szwarc, Daniel; Bierry, Guillaume; Gangi, Afshin

    2009-05-01

    Percutaneous image-guided thermal ablation of tumor is widely used, and thermal injury to collateral structures is a known complication of this technique. To avoid thermal damage to surrounding structures, several protection techniques have been reported. We report the use of a simple and effective protective technique combining carbon dioxide dissection and thermocouple: CO(2) displaces the nontarget structures, and its low thermal conductivity provides excellent insulation; insertion of a thermocouple in contact with vulnerable structures achieves continuous thermal monitoring. We performed percutaneous thermal ablation of 37 tumors in 35 patients (4 laser, 10 radiofrequency, and 23 cryoablations) with protection of adjacent vulnerable structures by using CO(2) dissection combined with continuous thermal monitoring with thermocouple. Tumor locations were various (19 intra-abdominal tumors including 4 livers and 9 kidneys, 18 musculoskeletal tumors including 11 spinal tumors). CO(2) volume ranged from 10 ml (epidural space) to 1500 ml (abdominal). Repeated insufflations were performed if necessary, depending on the information given by the thermocouple and imaging control. Dissection with optimal thermal protection was achieved in all cases except two patients where adherences (one postoperative, one arachnoiditis) blocked proper gaseous distribution. No complication referred to this technique was noted. This safe, cost-effective, and simple method increases the safety and the success rate of percutaneous thermal ablation procedures. It also offers the potential to increase the number of tumors that can be treated via a percutaneous approach.

  13. Tissue shrinkage in microwave ablation of liver: an ex vivo predictive model.

    PubMed

    Amabile, Claudio; Farina, Laura; Lopresto, Vanni; Pinto, Rosanna; Cassarino, Simone; Tosoratti, Nevio; Goldberg, S Nahum; Cavagnaro, Marta

    2017-02-01

    The aim of this study was to develop a predictive model of the shrinkage of liver tissues in microwave ablation. Thirty-seven cuboid specimens of ex vivo bovine liver of size ranging from 2 cm to 8 cm were heated exploiting different techniques: 1) using a microwave oven (2.45 GHz) operated at 420 W, 500 W and 700 W for 8 to 20 min, achieving complete carbonisation of the specimens, 2) using a radiofrequency ablation apparatus (450 kHz) operated at 70 W for a time ranging from 6 to 7.5 min obtaining white coagulation of the specimens, and 3) using a microwave (2.45 GHz) ablation apparatus operated at 60 W for 10 min. Measurements of specimen dimensions, carbonised and coagulated regions were performed using a ruler with an accuracy of 1 mm. Based on the results of the first two experiments a predictive model for the contraction of liver tissue from microwave ablation was constructed and compared to the result of the third experiment. For carbonised tissue, a linear contraction of 31 ± 6% was obtained independently of the heating source, power and operation time. Radiofrequency experiments determined that the average percentage linear contraction of white coagulated tissue was 12 ± 5%. The average accuracy of our model was determined to be 3 mm (5%). The proposed model allows the prediction of the shrinkage of liver tissues upon microwave ablation given the extension of the carbonised and coagulated zones. This may be useful in helping to predict whether sufficient tissue volume is ablated in clinical practice.

  14. UV solid state laser ablation of intraocular lenses

    NASA Astrophysics Data System (ADS)

    Apostolopoulos, A.; Lagiou, D. P.; Evangelatos, Ch.; Spyratou, E.; Bacharis, C.; Makropoulou, M.; Serafetinides, A. A.

    2013-06-01

    Commercially available intraocular lenses (IOLs) are manufactured from silicone and acrylic, both rigid (e.g. PMMA) and foldable (hydrophobic or hydrophilic acrylic biomaterials), behaving different mechanical and optical properties. Recently, the use of apodizing technology to design new diffractive-refractive multifocals improved the refractive outcome of these intraocular lenses, providing good distant and near vision. There is also a major ongoing effort to refine laser refractive surgery to correct other defects besides conventional refractive errors. Using phakic IOLs to treat high myopia potentially provides better predictability and optical quality than corneal-based refractive surgery. The aim of this work was to investigate the effect of laser ablation on IOL surface shaping, by drilling circular arrays of holes, with a homemade motorized rotation stage, and scattered holes on the polymer surface. In material science, the most popular lasers used for polymer machining are the UV lasers, and, therefore, we tried in this work the 3rd and the 5th harmonic of a Q-switched Nd:YAG laser (λ=355 nm and λ=213 nm respectively). The morphology of the ablated IOL surface was examined with a scanning electron microscope (SEM, Fei - Innova Nanoscope) at various laser parameters. Quantitative measurements were performed with a contact profilometer (Dektak-150), in which a mechanical stylus scanned across the surface of gold-coated IOLs (after SEM imaging) to measure variations in surface height and, finally, the ablation rates were also mathematically simulated for depicting the possible laser ablation mechanism(s). The experimental results and the theoretical modelling of UV laser interaction with polymeric IOLs are discussed in relation with the physical (optical, mechanical and thermal) properties of the material, in addition to laser radiation parameters (laser energy fluence, number of pulses). The qualitative aspects of laser ablation at λ=213 nm reveal a

  15. Efficacy and Safety of Radiofrequency Ablation for Benign Thyroid Nodules: A Prospective Multicenter Study

    PubMed Central

    Jung, So Lyung; Lee, Jeong Hyun; Shong, Young Kee; Sung, Jin Yong; Kim, Kyu Sun; Lee, Ducky; Kim, Ji-hoon; Baek, Seon Mi; Sim, Jung Suk; Na, Dong Gyu

    2018-01-01

    Objective To assess the efficacy and safety of thyroid radiofrequency (RF) ablation for benign thyroid nodules by trained radiologists according to a unified protocol in a multi-center study. Materials and Methods From 2010 to 2011, 345 nodules from 345 patients (M:F = 43:302; mean age ± SD = 46.0 ± 12.7 years, range = 15–79) who met eligibility criteria were enrolled from five institutions. At pre-ablation, the mean volume was 14.2 ± 13.2 mL (1.1–80.8 mL). For 12 months or longer after treatment, 276 lesions, consisting of 248 solid and 28 predominantly cystic nodules, were followed. All operators performed RF ablation with a cool-tip RF system and two standard techniques (a transisthmic approach and the moving-shot technique). Volume reduction at 12 months after RF ablation (the primary outcome), therapeutic success, improvement of symptoms as well as of cosmetic problems, and complications were evaluated. Multiple linear regression analysis was applied to identify factors that were independently predictive of volume reduction. Results The mean volume reduction at 12 months was 80.3% (n = 276) and at the 24-, 36-, 48-, and 60-month follow-ups 84.3% (n = 198), 89.2% (n = 128), 91.9% (n = 57), and 95.3% (n = 6), respectively. Our therapeutic success was 97.8%. Both mean symptom and cosmetic scores showed significant improvements (p < 0.001). The rate of major complications was 1.0% (3/276). Solidity and applied energy were independent factors that predicted volume reduction. Conclusion Radiofrequency ablation performed by trained radiologists from multiple institutions using a unified protocol and similar devices was effective and safe for treating benign thyroid nodules. PMID:29354014

  16. An approach to ablate and pace:AV junction ablation and pacemaker implantation performed concurrently from the same venous access site.

    PubMed

    Issa, Ziad F

    2007-09-01

    Atrioventricular junction (AVJ) ablation combined with permanent pacemaker implantation (the "ablate and pace" approach) remains an acceptable alternative treatment strategy for symptomatic, drug-refractory atrial fibrillation (AF) with rapid ventricular response. This case series describes the feasibility and safety of catheter ablation of the AVJ via a superior vena caval approach performed during concurrent dual-chamber pacemaker implantation. A total of 17 consecutive patients with symptomatic, drug-refractory, paroxysmal AF underwent combined AVJ ablation and dual-chamber pacemaker implantation procedure using a left axillary venous approach. Two separate introducer sheaths were placed into the axillary vein. The first sheath was used for implantation of the pacemaker ventricular lead, which was then connected to the pulse generator. Subsequently, a standard ablation catheter was introduced through the second axillary venous sheath and used for radiofrequency (RF) ablation of the AVJ. After successful ablation, the catheter was withdrawn and the pacemaker atrial lead was advanced through that same sheath and implanted in the right atrium. Catheter ablation of the AVJ was successfully achieved in all patients. The median number of RF applications required to achieve complete AV block was three (range 1-10). In one patient, AV conduction recovered within the first hour after completion of the procedure, and AVJ ablation was then performed using the conventional femoral venous approach. There were no procedural complications. Catheter ablation of the AVJ can be performed successfully and safely via a superior vena caval approach in patients undergoing concurrent dual-chamber pacemaker implantation.

  17. Ablative Thermal Protection Systems Fundamentals

    NASA Technical Reports Server (NTRS)

    Beck, Robin A. S.

    2017-01-01

    This is a presentation of the fundamentals of ablative TPS materials for a short course at TFAWS 2017. It gives an overall description of what an ablator is, the equations that define it, and how to model it.

  18. Clinical effects of non-ablative and ablative fractional lasers on various hair disorders: a case series of 17 patients.

    PubMed

    Cho, Suhyun; Choi, Min Ju; Zheng, Zhenlong; Goo, Boncheol; Kim, Do-Young; Cho, Sung Bin

    2013-04-01

    Both ablative and non-ablative fractional lasers have been applied to various uncommon hair disorders. The purpose of this study was to demonstrate the clinical effects of fractional laser therapy on the course of primary follicular and perifollicular pathologies and subsequent hair regrowth. A retrospective review of 17 patients with uncommon hair disorders - including ophiasis, autosomal recessive woolly hair/hypotrichosis, various secondary cicatricial alopecias, pubic hypotrichosis, frontal fibrosing alopecia, and perifolliculitis abscedens et suffodiens - was conducted. All patients had been treated with non-ablative and/or ablative fractional laser therapies. The mean clinical improvement score in these 17 patients was 2.2, while the mean patient satisfaction score was 2.5. Of the 17 subjects, 12 (70.6%) demonstrated a clinical response to non-ablative and/or ablative fractional laser treatments, including individuals with ophiasis, autosomal recessive woolly hair/hypotrichosis, secondary cicatricial alopecia (scleroderma and pressure-induced alopecia), frontal fibrosing alopecia, and perifolliculitis abscedens et suffodiens. Conversely, patients with long-standing ophiasis, surgical scar-induced secondary cicatricial alopecia, and pubic hypotrichosis did not respond to fractional laser therapy. Our findings demonstrate that the use of non-ablative and/or ablative fractional lasers promoted hair growth in certain cases of uncommon hair disorders without any remarkable side effects.

  19. High intensity focused ultrasound (HIFU) ablation of benign thyroid nodules - a systematic review.

    PubMed

    Lang, Brian Hung-Hin; Wu, Arnold L H

    2017-01-01

    With an increasing number of imaging studies being done nowadays, the number of incidentally discovered thyroid nodules is expected to rise. Although many of these nodules are small and benign in nature, some do grow and may cause pressure and/or thyrotoxic symptoms. Surgical resection has traditionally been recommended for symptomatic nodules but is associated with risk of hypothyroidism, bleeding, infection, and nerve damage. High intensity focused ultrasound (HIFU) is one of the non-surgical thermal ablation techniques that may serve as an alternative in the treatment of benign thyroid nodules. The present review is to systematically evaluate the efficacy and safety of HIFU ablation. We comprehensively searched all studies that evaluated the use of HIFU ablation as a treatment of benign thyroid nodules from Medline (PubMed) and Cochrane Library electronic databases using specific keywords. All titles identified by the search strategy were independently screened by two authors. Case reports, animal studies, editorials, expert opinions, reviews without original data and studies on pediatric population were excluded. Multiple reports of the same dataset were assessed and the most representative and updated report of a study was included. Five original studies were found. All treated thyroid nodules were confirmed to be benign cytologically and either appeared solid or predominantly (>70%) solid on ultrasonography. Only one type of commercially available US-guided device with an extracorporeal probe (3 MHz) was used in all the reported treatments. No major complications including recurrent laryngeal nerve injury, skin burn or haematoma were reported in all of the studies. The overall nodule volume reduction after single session of HIFU ablation ranged between 45 and 68%, depending on nodule size and length of follow-up. Despite the few number of studies, our review appeared to suggest that HIFU is a safe and efficacious method of treating symptomatic benign thyroid

  20. Elucidating the thermal, chemical, and mechanical mechanisms of ultraviolet ablation in poly(methyl methacrylate) via molecular dynamics simulations.

    PubMed

    Conforti, Patrick F; Prasad, Manish; Garrison, Barbara J

    2008-08-01

    [Figure: see text]. Laser ablation harnesses photon energy to remove material from a surface. Although applications such as laser-assisted in situ keratomileusis (LASIK) surgery, lithography, and nanoscale device fabrication take advantage of this process, a better understanding the underlying mechanism of ablation in polymeric materials remains much sought after. Molecular simulation is a particularly attractive technique to study the basic aspects of ablation because it allows control over specific process parameters and enables observation of microscopic mechanistic details. This Account describes a hybrid molecular dynamics-Monte Carlo technique to simulate laser ablation in poly(methyl methacrylate) (PMMA). It also discusses the impact of thermal and chemical excitation on the ensuing ejection processes. We used molecular dynamics simulation to study the molecular interactions in a coarse-grained PMMA substrate following photon absorption. To ascertain the role of chemistry in initiating ablation, we embedded a Monte Carlo protocol within the simulation framework. These calculations permit chemical reactions to occur probabilistically during the molecular dynamics calculation using predetermined reaction pathways and Arrhenius rates. With this hybrid scheme, we can examine thermal and chemical pathways of decomposition separately. In the simulations, we observed distinct mechanisms of ablation for each type of photoexcitation pathway. Ablation via thermal processes is governed by a critical number of bond breaks following the deposition of energy. For the case in which an absorbed photon directly causes a bond scission, ablation occurs following the rapid chemical decomposition of material. A detailed analysis of the processes shows that a critical energy for ablation can describe this complex series of events. The simulations show a decrease in the critical energy with a greater amount of photochemistry. Additionally, the simulations demonstrate the effects

  1. Laser Ablation-Aerosol Mass Spectrometry-Chemical Ionization Mass Spectrometry for Ambient Surface Imaging

    DOE PAGES

    Berry, Jennifer L.; Day, Douglas A.; Elseberg, Tim; ...

    2018-02-20

    Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. In this paper, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inletmore » providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. Finally, the results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.« less

  2. Laser Ablation-Aerosol Mass Spectrometry-Chemical Ionization Mass Spectrometry for Ambient Surface Imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berry, Jennifer L.; Day, Douglas A.; Elseberg, Tim

    Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. In this paper, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inletmore » providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. Finally, the results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.« less

  3. Radiofrequency Ablation Followed by Percutaneous Ethanol Ablation Leading to Long-Term Remission of Hyperparathyroidism

    PubMed Central

    Menon, Arun S.; Nazar, P. K.; Moorthy, Srikanth; Kumar, Harish; Nair, Vasantha; Pavithran, Praveen Valiyaparambil; Bhavani, Nisha; Menon, Vadayath Usha; Abraham, Nithya; Jayakumar, R. Vasukutty

    2017-01-01

    A 30-year-old male with cerebral palsy and motor impairment presented with right femur fracture. He had gradually worsening mobility and contractures of all extremities for the preceding 5 years. Evaluation showed multiple vertebral and femoral fractures, severe osteoporosis, a large parathyroid adenoma, and parathormone (PTH) exceeding 2500 pg/mL. Because of poor general health and high anesthetic risk, parathyroidectomy was deemed impractical. Ultrasound-guided radiofrequency ablation (RFA) helped achieve 50% size reduction and PTH levels with better control of hypercalcemia. Later, as calcium and PTH remained elevated, percutaneous ethanol ablation was performed with resultant normalization of PTH and substantial symptomatic improvement. Two years later, he still remains normocalcaemic with normal PTH levels. We propose that RFA and percutaneous ethanol ablation be considered as effective short-term options for surgically difficult cases, which could even help achieve long-term remission. Although not previously reported, our case illustrates that both RFA and percutaneous ethanol ablation could be safely performed successively achieving long-term remission. PMID:29264521

  4. Thermoplastic microchannel fabrication using carbon dioxide laser ablation.

    PubMed

    Wang, Shau-Chun; Lee, Chia-Yu; Chen, Hsiao-Ping

    2006-04-14

    We report the procedures of machining microchannels on Vivak co-polyester thermoplastic substrates using a simple industrial CO(2) laser marker. To avoid overheating the substrates, we develop low-power marking techniques in nearly anaerobic environment. These procedures are able to machine microchannels at various aspect ratios. Either straight or serpent channel can be easily marked. Like the wire-embossed channel walls, the ablated channel surfaces become charged after alkaline hydrolysis treatment. Stable electroosmotic flow in the charged conduit is observed to be of the same order of magnitude as that in fused silica capillary. Typical dynamic coating protocols to alter the conduit surface properties are transferable to the ablated channels. The effects of buffer acidity on electroosmotic mobility in both bare and coated channels are similar to those in fused silica capillaries. Using video microscopy we also demonstrate that this device is useful in distinguishing the electrophoretic mobility of bare and latex particles from that of functionalized ones.

  5. Connectivity changes after laser ablation: Resting-state fMRI.

    PubMed

    Boerwinkle, Varina L; Vedantam, Aditya; Lam, Sandi; Wilfong, Angus A; Curry, Daniel J

    2018-05-01

    Resting-state functional magnetic resonance imaging (rsfMRI) is emerging as a useful tool in the multimodal assessment of patients with epilepsy. In pediatric patients who cannot perform task-based fMRI, rsfMRI may present an adjunct and alternative. Although changes in brain activation during task-based fMRI have been described after surgery for epilepsy, there is limited data on the role of postoperative rsfMRI. In this short review, we discuss the role of postoperative rsfMRI after laser ablation of seizure foci. By establishing standardized anesthesia protocols and imaging parameters, we have been able to perform serial rsfMRI at postoperative follow-up. The development of in-house software that can merge rsfMRI images to surgical navigation systems has allowed us to enhance the clinical applications of this technique. Resting-state fMRI after laser ablation has the potential to identify changes in connectivity, localize new seizure foci, and guide antiepileptic therapy. In our experience, rsfMRI complements conventional MR imaging and task-based fMRI for the evaluation of patients with seizure recurrence after laser ablation, and represents a potential noninvasive biomarker for functional connectivity. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Nanosecond laser-metal ablation at different ambient conditions

    NASA Astrophysics Data System (ADS)

    Elsied, Ahmed M.; Dieffenbach, Payson C.; Diwakar, Prasoon K.; Hassanein, Ahmed

    2018-05-01

    Ablation of metals under different ambient conditions and laser fluences, was investigated through series of experiments. A 1064 nm, 6 ns Nd:YAG laser was used to ablate 1 mm thick metal targets with laser energy ranging from 2 mJ to 300 mJ. The experiments were designed to study the effect of material properties, laser fluence, ambient gas, and ambient pressure on laser-metal ablation. The first experiment was conducted under vacuum to study the effect of laser fluence and material properties on metal ablation, using a wide range of laser fluences (2 J/cm2 up to 300 J/cm2) and two different targets, Al and W. The second experiment was conducted at atmospheric pressure using two different ambient gases air and argon, to understand the effect of ambient gas on laser-metal ablation process. The third experiment was conducted at two different pressures (10 Torr and 760 Torr) using the same ambient gas to investigate the effect of ambient pressure on laser-metal ablation. To compare the different ablation processes, the amount of mass ablated, ablation depth, crater profile and melt formation were measured using White Light Profilometer (WLP). The experimental results show that at low laser fluence: the ablated mass, ablation depth, and height of molten layer follow a logarithmic function of the incident laser fluence. While, at high laser fluence they follow a linear function. This dependence on laser fluence was found to be independent on ambient conditions and irradiated material. The effect of ambient pressure was more pronounced than the effect of ambient gas type. Plasma shielding effect was found to be very pronounced in the presence of ambient gas and led to significant reduction in the total mass ablation.

  7. Radiofrequency ablation combined with transcatheter arterial embolisation in rabbit liver: investigation of the ablation zone according to the time interval between the two therapies.

    PubMed

    Lee, I J; Kim, Y I; Kim, K W; Kim, D H; Ryoo, I; Lee, M W; Chung, J W

    2012-11-01

    This study was designed to evaluate the extent of the radiofrequency ablation zone in relation to the time interval between transcatheter arterial embolisation (TAE) and radiofrequency ablation (RFA) and, ultimately, to determine the optimal strategy of combining these two therapies for hepatocellular carcinoma. 15 rabbits were evenly divided into three groups: Group A was treated with RFA alone; Group B was treated with TAE immediately followed by RFA; and Group C was treated with TAE followed by RFA 5 days later. All animals underwent perfusion CT (PCT) scans immediately after RFA. Serum liver transaminases were measured to evaluate acute liver damage. Animals were euthanised for pathological analysis of ablated tissues 10 days after RFA. Non-parametric analyses were conducted to compare PCT indices, the RFA zone and liver transaminase levels among the three experimental groups. Group B showed a significantly larger ablation zone than the other two groups. Arterial liver perfusion and hepatic perfusion index represented well the perfusion decrease after TAE on PCT. Although Group B showed the most elevated liver transaminase levels at 1 day post RFA, the enzymes decreased to levels that were not different from the other groups at 10 days post-RFA. When combined TAE and RFA therapy is considered, TAE should be followed by RFA as quickly as possible, as it can be performed safely without serious hepatic deterioration, despite the short interval between the two procedures.

  8. Graphite Ablation and Thermal Response Simulation Under Arc-Jet Flow Conditions

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Milos, F. S.; Reda, D. C.; Stewart, D. A.; Venkatapathy, Ethiraj (Technical Monitor)

    2002-01-01

    The Two-dimensional Implicit Thermal Response and Ablation program, TITAN, was developed and integrated with a Navier-Stokes solver, GIANTS, for multidimensional ablation and shape change simulation of thermal protection systems in hypersonic flow environments. The governing equations in both codes are demoralized using the same finite-volume approximation with a general body-fitted coordinate system. Time-dependent solutions are achieved by an implicit time marching technique using Gauess-Siedel line relaxation with alternating sweeps. As the first part of a code validation study, this paper compares TITAN-GIANTS predictions with thermal response and recession data obtained from arc-jet tests recently conducted in the Interaction Heating Facility (IHF) at NASA Ames Research Center. The test models are graphite sphere-cones. Graphite was selected as a test material to minimize the uncertainties from material properties. Recession and thermal response data were obtained from two separate arc-jet test series. The first series was at a heat flux where graphite ablation is mainly due to sublimation, and the second series was at a relatively low heat flux where recession is the result of diffusion-controlled oxidation. Ablation and thermal response solutions for both sets of conditions, as calculated by TITAN-GIANTS, are presented and discussed in detail. Predicted shape change and temperature histories generally agree well with the data obtained from the arc-jet tests.

  9. Morphologic changes in the vein after different numbers of radiofrequency ablation cycles.

    PubMed

    Shaidakov, Evgeny V; Grigoryan, Arsen G; Korzhevskii, Dmitriy E; Ilyukhin, Evgeny A; Rosukhovski, Dmitriy A; Bulatov, Vasiliy L; Tsarev, Oleg I

    2015-10-01

    It has not yet been clarified whether it is possible to decrease the percentage of recurrences after radiofrequency (RF) ablation by way of increasing the number of RF ablation cycles. The aim of this study was to assess the morphologic changes in excised vein fragments after different durations of RF ablation exposure. In the first part of the study, we performed a morphologic analysis of eight cases of great saphenous vein (GSV) recanalization 6 months after RF ablation. The second part was performed on a suprafascial segment of the GSV with a length of >22 cm and a minimum diameter of 5 mm in 10 patients, who had given their consent to intraoperative excision of suprafascial GSV segments after RF ablation treatment through four 1-cm-long diametrical cuts. Prior ultrasound analysis had shown an average 6.9-mm diameter of the suprafascial segments. The segment was divided into three 7-cm-long subsegments and one control segment. The first, second, and third segments were treated with three, two, and one RF ablation cycles (ClosureFast; Covidien, Mansfield, Mass), respectively; the control segment was not exposed to RF ablation at all. Morphologic study of 160 sections of the vein (five sections of each segment and 10 control specimens) was carried out. The specimens were dyed with hematoxylin and orcein. The ensuing analysis was performed by an experienced expert with the blind study method (the specimens were numbered without any hint as to the quantity of RF ablation cycles performed on them). The intergroup comparison of the depth of venous wall damage was based on comparison of the coefficient of alteration, which is calculated as the relation of damage depth to thickness of the vein. After one RF ablation cycle, the depth of blurring of the structural elements only on some portions reached the middle of the muscle layer of the wall (coefficient of alteration, α = 26%). After two cycles, blurring of the structural elements on some portions extended to the

  10. Laser-ablation ICP-MS as a tool for whole rock trace element analyses on fused powders

    NASA Astrophysics Data System (ADS)

    Girard, G.; Rooney, T. O.

    2013-12-01

    Here we present an accurate and precise technique for routine trace element analysis of geologic materials by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We focus on rock powders previously prepared for X-ray fluorescence by fusion in a Li2B4O7 flux, and subsequently quenched in a Pt mold to form a glass disk. Our method allows for the analysis up to 30 trace elements by LA-ICP-MS using a Photon-Machines Analyte G2 193 nm excimer laser coupled to a Thermo-Fisher Scientific ICAP Q quadrupole ICP-MS. Analyses are run as scans on the surface of the disks. Laser ablation conditions for which trace element fractionation effects are minimal have been empirically determined to be ~ 4 J m-2 fluence, at 10 Hz , and 10 μm s-1 scan speed, using a 110 μm laser beam size. Ablated material is carried into the ICP-MS by a He carrier at a rate of 0.75 L min-1. Following pre-ablation to remove surface particles, samples are ablated for 200 s, of which 140 s are used for data acquisition. At the end of each scan, a gas blank is collected for 30 s. Dwell times for each element vary between 15 and 60 μs, depending on abundance and instrument sensitivity, allowing 120 readings of each element during the data acquisition time window. To correct for variations in the total volume of material extracted by the laser, three internal standards are used, Ca, Fe and Zr. These elements are routinely analyzed by X-ray fluorescence by the Geoanalytical laboratory at Michigan State University with precision and accuracy of <5%. The availability of several internal standards allows for better correction of possible persisting laser ablation fractionation effects; for a particular trace element, we correct using the internal standard that best reproduces its ablation behavior. Our calibration is based on a combination of fused powders of US Geological Survey and Geological Survey of Japan rock standards, NIST SRM 612 glass, and US Geological Survey natural and

  11. Artificial meteor ablation studies - Iron oxides.

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.

    1972-01-01

    Artificial meteor ablation was performed on natural minerals composed predominantly of magnetite and hematite by using an arc-heated plasma stream of air. Analysis indicates that most of the ablated debris was composed of two or more minerals. Wustite, a metastable mineral, was found to occur as a common product. The 'magnetite' sample, which was 80% magnetite, 14% hematite, 4% apatite, and 2% quartz, yielded ablated products consisting of more than 12 different minerals. Magnetite occurred in 91% of the specimens examined, hematite in 16%, and wustite in 30%. The 'hematite' sample, which was 96% hematite and 3% quartz, yielded ablated products consisting of more than 13 different minerals. Hematite occurred in 47% of the specimens examined, magnetite in 60%, and wustite in 28%. The more volatile elements (Si, P, and Cl) were depleted by about 50%. This study has shown that artificially created ablation products from iron oxides exhibit unique properties that can be used for identification.

  12. Value of local electrogram characteristics predicting successful catheter ablation of left-versus right-sided accessory atrioventricular pathways by radiofrequency current.

    PubMed

    Lin, J L; Schie, J T; Tseng, C D; Chen, W J; Cheng, T F; Tsou, S S; Chen, J J; Tseng, Y Z; Lien, W P

    1995-01-01

    Despite similar guidance by local electrogram criteria, catheter ablation of right-sided accessory atrioventricular (AV) pathways by radiofrequency current has been less effective than that of left-sided ones. In order to elucidate the possible diversities in local electrosignal criteria, we systematically analyzed the morphological and timing characteristics of 215 bipolar local electrograms from catheter ablation sites of 65 left-sided accessory AV pathways and of 356 from those of 37 right-sided ones in 92 consecutive patients with Wolff-Parkinson-White syndrome or AV reentrant tachycardia incorporating concealed accessory AV pathways. After stepwise multivariate analysis, we selected the presence of a possible accessory pathway potential, local ventricular activation preceding QRS complex for 20 ms or more during ventricular insertion mapping, and the local retrograde ventriculoatrial (VA) continuity, local retrograde VA interval < or = 50 ms, electrogram stability (left-sided targets only), retrograde accessory pathway potential (right-sided targets only) during atrial insertion mapping, as independent local electrogram predictors for successful ablation of left- and right-sided accessory AV pathways. Combination of all local electrogram predictors could have moderate chance of success (80 and 51%) for the ventricular and atrial insertion ablation of left-sided accessory AV pathways, but only low probability of success (40% in ventricular insertion ablation) or very low sensitivity (12.5% in atrial insertion ablation) for right-sided ones. In conclusion, with the present approach, successful catheter ablation of right-sided accessory AV pathways, compared to left-sided ones, still necessitate a breakthrough in the precision mapping and the efficiency of energy delivery.

  13. Flexible Ablators: Applications and Arcjet Testing

    NASA Technical Reports Server (NTRS)

    Arnold, James O.; Venkatapathy, Ethiraj; Beck, Robin A S.; Mcguire, Kathy; Prabhu, Dinesh K.; Gorbunov, Sergey

    2011-01-01

    Flexible ablators were conceived in 2009 to meet the technology pull for large, human Mars Exploration Class, 23 m diameter hypersonic inflatable aerodynamic decelerators. As described elsewhere, they have been recently undergoing initial technical readiness (TRL) advancement by NASA. The performance limits of flexible ablators in terms of maximum heat rates, pressure and shear remain to be defined. Further, it is hoped that this emerging technology will vastly expand the capability of future NASA missions involving atmospheric entry systems. This paper considers four topics of relevance to flexible ablators: (1) Their potential applications to near/far term human and robotic missions (2) Brief consideration of the balance between heat shield diameter, flexible ablator performance limits, entry vehicle controllability and aft-body shear layer impingement of interest to designers of very large entry vehicles, (3) The approach for developing bonding processes of flexible ablators for use on rigid entry bodies and (4) Design of large arcjet test articles that will enable the testing of flexible ablators in flight-like, combined environments (heat flux, pressure, shear and structural tensile loading). Based on a review of thermal protection system performance requirements for future entry vehicles, it is concluded that flexible ablators have broad applications to conventional, rigid entry body systems and are enabling to large deployable (both inflatable and mechanical) heat shields. Because of the game-changing nature of flexible ablators, it appears that NASA's Office of the Chief Technologist (OCT) will fund a focused, 3-year TRL advancement of the new materials capable of performance in heat fluxes in the range of 200-600 W/sq. cm. This support will enable the manufacture and use of the large-scale arcjet test designs that will be a key element of this OCT funded activity.

  14. Laser ablation-miniature mass spectrometer for elemental and isotopic analysis of rocks.

    PubMed

    Sinha, M P; Neidholdt, E L; Hurowitz, J; Sturhahn, W; Beard, B; Hecht, M H

    2011-09-01

    A laser ablation-miniature mass spectrometer (LA-MMS) for the chemical and isotopic measurement of rocks and minerals is described. In the LA-MMS method, neutral atoms ablated by a pulsed laser are led into an electron impact ionization source, where they are ionized by a 70 eV electron beam. This results in a secondary ion pulse typically 10-100 μs wide, compared to the original 5-10 ns laser pulse duration. Ions of different masses are then spatially dispersed along the focal plane of the magnetic sector of the miniature mass spectrometer (MMS) and measured in parallel by a modified CCD array detector capable of detecting ions directly. Compared to conventional scanning techniques, simultaneous measurement of the ion pulse along the focal plane effectively offers a 100% duty cycle over a wide mass range. LA-MMS offers a more quantitative assessment of elemental composition than techniques that detect ions directly generated by the ablation process because the latter can be strongly influenced by matrix effects that vary with the structure and geometry of the surface, the wavelength of the laser beam, and the not well characterized ionization efficiencies of the elements in the process. The above problems attendant to the direct ion analysis has been minimized in the LA-MMS by analyzing the ablated neutral species after their post-ionization by electron impaction. These neutral species are much more abundant than the directly ablated ions in the ablated vapor plume and are, therefore, expected to be characteristic of the chemical composition of the solid. Also, the electron impact ionization of elements is well studied and their ionization cross sections are known and easy to find in databases. Currently, the LA-MMS limit of detection is 0.4 wt.%. Here we describe LA-MMS elemental composition measurements of various minerals including microcline, lepidolite, anorthoclase, and USGS BCR-2G samples. The measurements of high precision isotopic ratios including (41)K

  15. Advanced Rigid Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    NASA Exploration Systems Mission Directorate s (ESMD) Entry, Descent, and Landing (EDL) Technology Development Project (TDP) and the NASA Aeronautics Research Mission Directorate s (ARMD) Hypersonics Project are developing new advanced rigid ablators in an effort to substantially increase reliability, decrease mass, and reduce life cycle cost of rigid aeroshell-based entry systems for multiple missions. Advanced Rigid Ablators combine ablation resistant top layers capable of high heat flux entry and enable high-speed EDL with insulating mass-efficient bottom that, insulate the structure and lower the areal weight. These materials may benefit Commercial Orbital Transportation Services (COTS) vendors and may potentially enable new NASA missions for higher velocity returns (e.g. asteroid, Mars). The materials have been thermally tested to 400-450 W/sq cm at the Laser Hardened Materials Evaluation Lab (LHMEL), Hypersonics Materials Evaluation Test System (HyMETS) and in arcjet facilities. Tested materials exhibit much lower backface temperatures and reduced recession over the baseline materials (PICA). Although the EDL project is ending in FY11, NASA in-house development of advanced ablators will continue with a focus on varying resin systems and fiber/resin interactions.

  16. Pulsed laser ablation of borax target in vacuum and hydrogen DC glow discharges

    NASA Astrophysics Data System (ADS)

    Kale, A. N.; Miotello, A.; Mosaner, P.

    2006-09-01

    The aim of our experiment was to produce a material with B sbnd H bonds for applications in hydrogen storage and generation. By using KrF excimer laser ( λ = 248 nm) ablation of borax (Na 2B 4O 7) target, thin films were deposited on KBr and silicon substrates. Ablation was performed both in vacuum and in hydrogen atmosphere. DC glow discharge technique was utilized to enhance hydrogen gas ionization. Experiments were performed using laser fluence from 5 to 20 J/cm 2. Films were deposited under gas pressure of 1 × 10 -5 to 5 × 10 -2 mbar and substrate temperatures of 130-450 °C. Scanning electron microscopy analysis of films showed presence of circular particulates. Film thickness, roughness and particulates number increased with increase in laser fluence. Energy dispersive X-ray spectroscopy analysis shows that sodium content in the particulates is higher than in the target. This effect is discussed in terms of atomic arrangements (both at surface and bulk) in systems where ionic and covalent bonds are present and by looking at the increased surface/bulk ratio of the particulates with respect to the deposited films. The Fourier transform infrared spectroscopy measurements showed presence of B sbnd O stretching and B sbnd O sbnd B bending bonds. Possible reasons for absence of B sbnd H bonds are attributed to binding enthalpy of the competing molecules.

  17. Microwave ablation of pancreatic head cancer: safety and efficacy.

    PubMed

    Carrafiello, Gianpaolo; Ierardi, Anna Maria; Fontana, Federico; Petrillo, Mario; Floridi, Chiara; Lucchina, Natalie; Cuffari, Salvatore; Dionigi, Gianlorenzo; Rotondo, Antonio; Fugazzola, Carlo

    2013-10-01

    To evaluate the safety and efficacy of percutaneous microwave (MW) ablation treatment in locally advanced, nonresectable, nonmetastatic pancreatic head cancer. Ten patients with pancreatic head cancer treated with percutaneous (n = 5) or laparotomic (n = 5) MW ablation were retrospectively reviewed. The MW generator used (45 W at 915 MHz) was connected by coaxial cable to 14-gauge straight MW antennas with a 3.7- or 2-cm radiating section. One or two antennae were used, with an ablation time of 10 minutes. Ultrasonographic (US) and combined US/cone-beam computed tomographic (CT) guidance were used in five patients each. Follow-up was performed by CT after 1, 3, 6, and, when possible, 12 months. Tumor response was assessed per Response Evaluation Criteria In Solid Tumors (version 1.1) and Choi criteria. The feasibility, safety, and major and minor complications associated with quality of life (QOL) were recorded prospectively. The procedure was feasible in all patients (100%). One late major complication was observed in one patient, and no visceral injury was detected. No patient had further surgery, and all minor complications resolved during the hospital stay. An improvement in QOL was observed in all patients despite a tendency to return to preoperative levels in the months following the procedure, without the influence of minor complications. No repeat treatment was performed. Despite the small number of patients, the present results can be considered encouraging, showing that MW ablation is a feasible approach in the palliative treatment of pancreatic tumors. © SIR, 2013.

  18. Convergent ablation measurements of plastic ablators in gas-filled rugby hohlraums on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Jalinaud, T.; Masse, L.; Galmiche, D.

    2015-10-01

    Indirect-drive implosions experiments were conducted on the Omega Laser Facility to test the performance of uniformly doped plastic ablators for Inertial Confinement Fusion. The first convergent ablation measurements in gas-filled rugby hohlraums are reported. Ignition relevant limb velocities in the range from 150 to 300 μm .n s-1 have been reached by varying the laser drive energy and the initial capsule aspect ratio. The measured capsule trajectory and implosion velocity are in good agreement with 2D integrated simulations and a zero-dimensional modeling of the implosions. We demonstrate experimentally the scaling law for the maximum implosion velocity predicted by the improved rocket model [Y. Saillard, Nucl. Fusion 46, 1017 (2006)] in the high-ablation regime case.

  19. Prospective study of atrial fibrillation termination during ablation guided by automated detection of fractionated electrograms.

    PubMed

    Porter, Michael; Spear, William; Akar, Joseph G; Helms, Ray; Brysiewicz, Neil; Santucci, Peter; Wilber, David J

    2008-06-01

    Complex fractionated atrial electrograms (CFAE) may identify critical sites for perpetuation of atrial fibrillation (AF) and provide useful targets for ablation. Current assessment of CFAE is subjective; automated detection algorithms may improve reproducibility, but their utility in guiding ablation has not been tested. In 67 patients presenting for initial AF ablation (42 paroxysmal, 25 persistent), LA and CS mapping were performed during induced or spontaneous AF. CFAE were identified by an online automated computer algorithm and displayed on electroanatomical maps. A mean of 28 +/- 18 sites/patient were identified (20 +/- 13% of mapped sites), and were more frequent during persistent AF. CFAE occurred most commonly within the CS, on the atrial septum, and around the pulmonary veins. Ablation initially targeting CFAE terminated AF in 88% of paroxysmal AF, but only 20% of persistent AF (P < 0.001). Subsequently, additional ablation was performed in all patients (PV isolation for paroxysmal AF, PV isolation + mitral and roof lines for persistent AF). Minimum follow-up was 1 year. One-year freedom from recurrent atrial arrhythmias without antiarrhythmic drug therapy after a single procedure was 90% for paroxysmal AF, and 68% for persistent AF. Ablation guided by automated detection of CFAE proved feasible, and was associated with a high AF termination rate in paroxysmal, but not persistent AF. As an adjunct to conventional techniques, it was associated with excellent long-term single procedure outcomes in both groups. Criteria for identifying optimal CFAE sites for ablation, and selection of patients most likely to benefit, require additional study.

  20. Fractional ablative laser skin resurfacing: a review.

    PubMed

    Tajirian, Ani L; Tarijian, Ani L; Goldberg, David J

    2011-12-01

    Ablative laser technology has been in use for many years now. The large side effect profile however has limited its use. Fractional ablative technology is a newer development which combines a lesser side effect profile along with similar efficacy. In this paper we review fractional ablative laser skin resurfacing.

  1. Safety and feasibility of single-catheter ablation using remote magnetic navigation for treatment of slow-fast atrioventricular nodal reentrant tachycardia compared to conventional ablation strategies.

    PubMed

    Akca, Ferdi; Schwagten, Bruno; Theuns, Dominic A J; Takens, Marieke; Musters, Paul; Szili-Torok, Tamas

    2013-12-01

    Ablation of atrioventricular nodal re-entrant tachycardia (AVNRT) is a highly effective procedure both with radiofrequency (RF) and cryoenergy (CE). Conventionally, it requires several diagnostic catheters and hospital admission. This study assessed the safety and efficacy of a highly simplified approach using the magnetic navigation system (MNS) compared to CE and manual RF ablation (MAN). In the MNS group a single magnetic-guided quadripolar catheter was inserted through the internal jugular vein to perform ablation. In the CE group cryomapping preceded ablation and for MAN procedures conventional ablation was performed. The following parameters were analysed: success- and recurrence rate, procedure-, fluoroscopy- and total application time. In total 69 eligible patients were treated with MNS (n = 26), CE (n = 25) and MAN (n = 16). The success rates were 100%, 100% and 94%, respectively (p = ns). The mean procedural time was 83 +/- 25 min for MNS, 117 +/- 47 min for CE and 117 +/- 55 min for MAN (P < 0.01). Total radiation time was significantly lower for MNS [0.0 min (IQR 0.0-0.0)] compared to CE [15.1 min (IQR 9.1-23.8), P < 0.001] and MAN [17.5 min (IQR 7.0-31.3), P < 0.001]. The total application time was comparable for both RF groups: 357 +/- 315 s (MNS) vs 204 +/- 177 s (MAN) (P = 0.14). No major adverse events occurred. After 3 months follow-up similar PR intervals were recorded for all patients. During a follow-up of 26 +/- 5 months recurrence rates were 3.8%, 4.0% and 6.3%, respectively, for each group. The MNS-guided single-catheter approach is a feasible and safe technique for the treatment of patients with typical AVNRT.

  2. Investigation of low-cost fabrication of ablative heat shields

    NASA Technical Reports Server (NTRS)

    Massions, V. P.; Mach, R. W.

    1973-01-01

    The fabrication, testing, and evaluation of materials and techniques employed in the fabrication of ablative heat shield panels are described. Results of this effort show projected reductions in labor man-hours for dielectric curing of panels when compared to panels molded in a steam-heated press. In addition, panels were fabricated with more than one density within the cross-section. These dual-density panels show significant weight and cost reduction potentials.

  3. Atrial Fibrillation Radiofrequency Ablation: Safety Using Contact Force Catheter In A Low-Volume Centre.

    PubMed

    Vaccari Md, Diego; Giacopelli MSc, Daniele; Rocchetto MSc, Eros; Vittadello Md, Sabina; Mantovan Md, Roberto; Neri Md, Gianfilippo

    2014-01-01

    The tip-to-tissue contact force (CF) has been identified as a potential determinant of lesion quality during radiofrequency (RF) ablation. The aim of this paper is to report the experience of a single low-volume centre in the atrial fibrillation (AF) ablation procedure with an RF catheter capable of measuring this parameter. CF data and their possible implications on patient safety are presented. Thirty-nine consecutive patients suffering of paroxysmal or permanent AF received percutaneous ablation with the novel catheter studied. Procedural characteristics, CF applied and safety events related to the procedure were reported. During RF application the mean CF value was 17 ± 3 g, with a maximum mean value of 37 ± 8 g. CF value never exceeded 62 g and in the 74% of the RF applications ranged between 10 g and 30 g. No complication related to the catheter manipulation or to the energy delivered was observed. This study of a single centre with a low level of experience in AF ablation suggests that the ability to measure CF may provide additional useful information to the operator. It ensures uniform ablations, with little variability in the catheter manipulations, and it avoids excessive contact forces increasing the patient safety.

  4. Evaluation of pain during high-intensity focused ultrasound ablation of benign thyroid nodules.

    PubMed

    Lang, Brian H H; Woo, Yu-Cho; Chiu, Keith Wan-Hang

    2018-06-01

    To assess severity and factors of pain during high-intensity focused ultrasound (HIFU) ablation of benign thyroid nodules. 128 patients who underwent a HIFU ablation for a benign thyroid nodule were analysed. All patients received a bolus of intravenous pethidine and diazepam before treatment. After treatment, patients were asked to rate their overall pain experience on a visual analogue scale (0-100) (0 = no pain; 100 = worse possible pain) during treatment, 2 h after treatment and the following morning. Binary logistic regression was performed to evaluate associated factors for pain including patient demographics, nodule size, body mass index (BMI) and treatment parameters. At T1, median (range) pain score was 65.0 (0.00-100.00). Only 16 (12.5 %) patients had a pain score of zero. In multivariate analysis, only lower BMI (OR 1.265, 95 % CI 1.102-1.452, p=0.001) and longer nodule diameter (OR 1.462, 95 % CI 1.071-1.996, p=0.017) were independent factors for pain score at T1 ≤ 65.0. A moderate to severe amount of pain was reported during ablation of benign thyroid nodules in over 50 % of patients. Patients' BMI and length of nodule diameter were independent variables for pain during HIFU ablation. • Pain was moderate to severe during HIFU ablation of thyroid nodules. • Only one in eight patients reported no pain during ablation. • Level of energy per pulse did not affect pain. • Patients with lower BMI and larger nodules had less pain.

  5. Emission intensity modulation of radio-frequency helium glow-discharge emission source by laser ablation.

    PubMed

    Matsuta, Hideyuki; Naeem, Tariq M; Wagatsuma, Kazuaki

    2003-06-01

    A novel emission excitation source comprising a high repetition rate diode-pumped Q-switched Nd:YAG laser and a Grimm-style glow-discharge lamp is described. Laser-ablated atoms are introduced into the He glow discharge plasma, which then give emission signals. By using phase-sensitive detection with a lock-in amplifier, the emission signal modulated by the pulsed laser can be detected selectively. It is possible to estimate only the emission intensity of sample atoms ablated by laser irradiation with little interference from the other species in the plasma.

  6. History, ethics, advantages and limitations of experimental models for hepatic ablation.

    PubMed

    Ong, Seok Ling; Gravante, Gianpiero; Metcalfe, Matthew S; Dennison, Ashley R

    2013-01-14

    Numerous techniques developed in medicine require careful evaluation to determine their indications, limitations and potential side effects prior to their clinical use. At present this generally involves the use of animal models which is undesirable from an ethical standpoint, requires complex and time-consuming authorization, and is very expensive. This process is exemplified in the development of hepatic ablation techniques, starting experiments on explanted livers and progressing to safety and efficacy studies in living animals prior to clinical studies. The two main approaches used are ex vivo isolated non-perfused liver models and in vivo animal models. Ex vivo non perfused models are less expensive, easier to obtain but not suitable to study the heat sink effect or experiments requiring several hours. In vivo animal models closely resemble clinical subjects but often are expensive and have small sample sizes due to ethical guidelines. Isolated perfused ex vivo liver models have been used to study drug toxicity, liver failure, organ transplantation and hepatic ablation and combine advantages of both previous models.

  7. SnO2/Pt Thin Film Laser Ablated Gas Sensor Array

    PubMed Central

    Shahrokh Abadi, Mohammad Hadi; Hamidon, Mohd Nizar; Shaari, Abdul Halim; Abdullah, Norhafizah; Wagiran, Rahman

    2011-01-01

    A gas sensor array was developed in a 10 × 10 mm2 space using Screen Printing and Pulse Laser Ablation Deposition (PLAD) techniques. Heater, electrode, and an insulator interlayer were printed using the screen printing method on an alumina substrate, while tin oxide and platinum films, as sensing and catalyst layers, were deposited on the electrode at room temperature using the PLAD method, respectively. To ablate SnO2 and Pt targets, depositions were achieved by using a 1,064 nm Nd-YAG laser, with a power of 0.7 J/s, at different deposition times of 2, 5 and 10 min, in an atmosphere containing 0.04 mbar (4 kPa) of O2. A range of spectroscopic diffraction and real space imaging techniques, SEM, EDX, XRD, and AFM were used in order to characterize the surface morphology, structure, and composition of the films. Measurement on the array shows sensitivity to some solvent and wood smoke can be achieved with short response and recovery times. PMID:22164041

  8. Application of erbium: YAG laser in ocular ablation.

    PubMed

    Tsubota, K

    1990-01-01

    Recent developments in lasers have provided us the possibility of laser ocular surgery. The xenon, argon, neodymium:YAG and dye lasers have been successfully used in out-patient clinics. The excimer laser has been attracting researchers' interest in the new application of laser to cornea and lens. The erbium:YAG laser emits a 2.94-microns beam that can ablate the transparent ocular tissues such as lenses and corneas. The author has applied this laser to the cornea, lens, vitreous and other ocular tissues. The erbium:YAG laser beam was directed through a 1.5-meter-long, 200-microns-diameter fiberoptic guide. The radiant energy measured about 50 mJ at the end of the probe. The laser was emitted as a 400-microsecond pulse. Freshly enucleated rabbit eyes were used in this study. Laser burns were applied to the tissue surface at various energy settings. At minimal power, the tissues were coagulated by the erbium:YAG laser application. At a power of more than 636-954 mJ/mm2, tissue began to evaporate; the tissue loss was observed under a surgical light microscope. Corneal photoablation, lens ablation, iridotomy, trabeculotomy, cutting of the vitreous and retinal ablation were easily performed. Like the excimer laser, the erbium:YAG laser is a potential tool for ocular surgery.

  9. Emergency catheter ablation in critical patients

    PubMed Central

    Tebbenjohanns, Jürgen; Rühmkorf, Klaus

    2010-01-01

    Emergency catheter ablation is justified in critical patients with drug-refractory life-threatening arrhythmias. The procedure can be used for ablation of an accessory pathway in preexcitation syndrome with high risk of ventricular fibrillation and in patients with shock due to ischemic cardiomyopathy and incessant ventricular tachycardia. Emergency catheter ablation can also be justified in patients with an electrical storm of the implanted cardioverter-defibrillator or in patients with idiopathic ventricular fibrillation. PMID:20606793

  10. Analysis of excimer laser radiant exposure effect toward corneal ablation volume at LASIK procedure

    NASA Astrophysics Data System (ADS)

    Adiati, Rima Fitria; Rini Rizki, Artha Bona; Kusumawardhani, Apriani; Setijono, Heru; Rahmadiansah, Andi

    2016-11-01

    LASIK (Laser Asissted In Situ Interlamelar Keratomilieusis) is a technique for correcting refractive disorders of the eye such as myopia and astigmatism using an excimer laser. This procedure use photoablation technique to decompose corneal tissues. Although preferred due to its efficiency, permanency, and accuracy, the inappropriate amount radiant exposure often cause side effects like under-over correction, irregular astigmatism and problems on surrounding tissues. In this study, the radiant exposure effect toward corneal ablation volume has been modelled through several processes. Data collecting results is laser data specifications with 193 nm wavelength, beam diameter of 0.065 - 0.65 cm, and fluence of 160 mJ/cm2. For the medical data, the myopia-astigmatism value, cornea size, corneal ablation thickness, and flap data are taken. The first modelling step is determining the laser diameter between 0.065 - 0.65 cm with 0.45 cm increment. The energy, power, and intensity of laser determined from laser beam area. Number of pulse and total energy is calculated before the radiant exposure of laser is obtained. Next is to determine the parameters influence the ablation volume. Regression method used to create the equation, and then the spot size is substituted to the model. The validation used is statistic correlation method to both experimental data and theory. By the model created, it is expected that any potential complications can be prevented during LASIK procedures. The recommendations can give the users clearer picture to determine the appropriate amount of radiant exposure with the corneal ablation volume necessary.

  11. Ablation properties of carbon/carbon composites with tungsten carbide

    NASA Astrophysics Data System (ADS)

    Yin, Jian; Zhang, Hongbo; Xiong, Xiang; Huang, Baiyun; Zuo, Jinlv

    2009-02-01

    The ablation properties and morphologies of carbon/carbon (C/C) composites with tungsten carbide (WC) filaments were investigated by ablation test on an arc heater and scanning electron microscopy. And the results were compared with those without tungsten carbide (WC) filaments tested under the same conditions. It shows that there is a big difference between C/C composites with and without WC filaments on both macroscopic and microscopic ablation morphologies and the ablation rates of the former are higher than the latter. It is found that the ablation process of C/C composites with WC filaments includes oxidation of carbon fibers, carbon matrices and WC, melting of WC and WO 3, and denudation of WC, WO 3 and C/C composites. Oxidation and melting of WC leads to the formation of holes in z directional carbon fiber bundles, which increases the coarseness of the ablation surfaces of the composites, speeds up ablation and leads to the higher ablation rate. Moreover, it is further found that the molten WC and WO 3 cannot form a continuous film on the ablation surface to prevent further ablation of C/C composites.

  12. Photoacoustic characterization of radiofrequency ablation lesions

    NASA Astrophysics Data System (ADS)

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

    2012-02-01

    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

  13. The effects of Magnetic Resonance Imaging-guided High-Intensity Focused Ultrasound ablation on human cadaver breast tissue.

    PubMed

    Merckel, Laura G; Deckers, Roel; Baron, Paul; Bleys, Ronald L A W; van Diest, Paul J; Moonen, Chrit T W; Mali, Willem P Th M; van den Bosch, Maurice A A J; Bartels, Lambertus W

    2013-10-05

    Magnetic Resonance Imaging-guided High-Intensity Focused Ultrasound (MR-HIFU) is a promising technique for non-invasive breast tumor ablation. The purpose of this study was to investigate the effects of HIFU ablation and thermal exposure on ex vivo human breast tissue. HIFU ablations were performed in three unembalmed cadaveric breast specimens using a clinical MR-HIFU system. Sonications were performed in fibroglandular and adipose tissue. During HIFU ablation, time-resolved anatomical MR images were acquired to monitor macroscopic tissue changes. Furthermore, the breast tissue temperature was measured using a thermocouple to investigate heating and cooling under HIFU exposure. After HIFU ablation, breast tissue samples were excised and prepared for histopathological analysis. In addition, thermal exposure experiments were performed to distinguish between different levels of thermal damage using immunohistochemical staining. Irreversible macroscopic deformations up to 3.7 mm were observed upon HIFU ablation both in fibroglandular and in adipose tissue. No relationship was found between the sonication power or the maximum tissue temperature and the size of the deformations. Temperature measurements after HIFU ablation showed a slow decline in breast tissue temperature. Histopathological analysis of sonicated regions demonstrated ablated tissue and morphologically complete cell death. After thermal exposure, samples exposed to three different temperatures could readily be distinguished. In conclusion, the irreversible macroscopic tissue deformations in ex vivo human breast tissue observed during HIFU ablation suggest that it might be relevant to monitor tissue deformations during MR-HIFU treatments. Furthermore, the slow decrease in breast tissue temperature after HIFU ablation increases the risk of heat accumulation between successive sonications. Since cell death was inflicted after already 5 minutes at 75°C, MR-HIFU may find a place in non-invasive treatment of

  14. In-Situ Apatite Laser Ablation U-Th-Sm/He Dating, Methods and Challenges

    NASA Astrophysics Data System (ADS)

    Pickering, J. E.; Matthews, W.; Guest, B.; Hamilton, B.; Sykes, C.

    2015-12-01

    In-situ, laser ablation U-Th-Sm/He dating is an emerging technique in thermochronology that has been proven as a means to date zircon and monzonite1-5. In-situ U-Th-Sm/He thermochronology eliminates many of the problems and inconveniences associated with traditional, whole grain methods, including; reducing bias in grain selection based on size, shape and clarity; allowing for the use of broken grains and grains with inclusions; avoiding bad neighbour effects; and eliminating safety hazards associated with dissolution. In-situ apatite laser ablation is challenging due to low concentrations of U and Th and thus a low abundance of radiogenic He. For apatite laser ablation to be effective the ultra-high-vacuum (UHV) line must have very low and consistent background levels of He. To reduce He background, samples are mounted in a UHV stable medium. Our mounting process uses a MicroHePP (Microscope Mounted Heated Platen Press) to press samples into FEP (fluorinated ethylene propylene) bonded to an aluminum backing plate. Samples are ablated using a Resonetics 193 nm excimer laser and liberated He is measured using a quadrupole mass spectrometer on the ASI Alphachron noble gas line; collectively this system is known as the Resochron. The ablated sites are imaged using a Zygo Zescope optical profilometer and ablated pit volume measured using PitVol, a custom MatLab algorithm developed to enable precise and unbiased measurement of the ablated pit geometry. We use the well-characterized Durango apatite to demonstrate the accuracy and precision of the method. He liberated from forty-two pits, having volumes between 1700 and 9000 um3, were measured using the Resochron. The ablated sites were imaged using a Zygo Zescope optical profilometer and ablated pit volume measured using PitVol. U, Th and Sm concentrations were measured by laser ablation and the U-Th-Sm/He age calculated by standard age equation. An age of 33.8±0.31 Ma was determined and compares well with conventional

  15. A Fluorescence-Guided Laser Ablation System for Removal of Residual Cancer in a Mouse Model of Soft Tissue Sarcoma.

    PubMed

    Lazarides, Alexander L; Whitley, Melodi J; Strasfeld, David B; Cardona, Diana M; Ferrer, Jorge M; Mueller, Jenna L; Fu, Henry L; Bartholf DeWitt, Suzanne; Brigman, Brian E; Ramanujam, Nimmi; Kirsch, David G; Eward, William C

    2016-01-01

    The treatment of soft tissue sarcoma (STS) generally involves tumor excision with a wide margin. Although advances in fluorescence imaging make real-time detection of cancer possible, removal is limited by the precision of the human eye and hand. Here, we describe a novel pulsed Nd:YAG laser ablation system that, when used in conjunction with a previously described molecular imaging system, can identify and ablate cancer in vivo. Mice with primary STS were injected with the protease-activatable probe LUM015 to label tumors. Resected tissues from the mice were then imaged and treated with the laser using the paired fluorescence-imaging/ laser ablation device, generating ablation clefts with sub-millimeter precision and minimal underlying tissue damage. Laser ablation was guided by fluorescence to target tumor tissues, avoiding normal structures. The selective ablation of tumor implants in vivo improved recurrence-free survival after tumor resection in a cohort of 14 mice compared to 12 mice that received no ablative therapy. This prototype system has the potential to be modified so that it can be used during surgery to improve recurrence-free survival in patients with cancer.

  16. Laser-launched flyer plate and confined laser ablation for shock wave loading: validation and applications.

    PubMed

    Paisley, Dennis L; Luo, Sheng-Nian; Greenfield, Scott R; Koskelo, Aaron C

    2008-02-01

    We present validation and some applications of two laser-driven shock wave loading techniques: laser-launched flyer plate and confined laser ablation. We characterize the flyer plate during flight and the dynamically loaded target with temporally and spatially resolved diagnostics. With transient imaging displacement interferometry, we demonstrate that the planarity (bow and tilt) of the loading induced by a spatially shaped laser pulse is within 2-7 mrad (with an average of 4+/-1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible, in particular, when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation allows for flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These techniques can be utilized to investigate such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples.

  17. Carbon Dioxide Laser Ablation of Basal Cell Carcinoma with Visual Guidance by Reflectance Confocal Microscopy: A Proof of Principle Pilot Study

    PubMed Central

    Hibler, B.P.; Sierra, H.; Cordova, M.; Phillips, W.; Rajadhyaksha, M.; Nehal, K.S.; Rossi, A.M.

    2016-01-01

    Background Laser ablation is an alternative, non-surgical treatment modality for low-risk basal cell carcinoma (BCC); however, lack of confirmative tumour destruction or residual tumour presence has been a limiting factor to adoption. Reflectance confocal microscopy (RCM) provides non-invasive, cellular-level resolution imaging of the skin and is capable of identifying tumour. Objective To evaluate the use of RCM to guide carbon dioxide (CO2) laser ablation of BCC, confirm destruction, and correlate findings with histology. Methods RCM was used pre-ablation to evaluate for features of BCC. Ablation was performed with a CO2 laser, and the response rapidly assessed using handheld RCM to evaluate for residual tumour. Confirmative pathology was used to verify confocal imaging. Results RCM imaging identified tumour pre-ablation with features not identified on normal, surrounding skin. Post-ablation, RCM documented complete removal of tumour in six cases and residual tumour in two. Histologic examination identified the ablated area and confirmed clearance of tumour in the six aforementioned cases and corroborated confocal findings for residual tumour in the other two cases. Conclusions We report successful treatment of superficial and nodular BCC using CO2 laser ablation augmented by RCM imaging for pre-ablation guidance and verification of tumour removal post-ablation. Akin to complete circumferential and deep margin control techniques, using RCM helps to map peripheral and deep BCC margins to hone in on areas exhibiting persistent tumour after ablation. CO2 laser ablation visually guided by RCM can help circumvent previously cited limiting factors of laser ablation for tumour destruction by providing cellular-level resolution imaging of tumour and margin assessment in between each laser pass and post-ablation. PMID:26800657

  18. Improved performance of selective ablation using a specially designed handpiece

    NASA Astrophysics Data System (ADS)

    Hennig, Thomas; Rechmann, Peter

    1996-01-01

    Selective ablation is fixed to a range of fluences predicted by the ablation thresholds of infected and healthy tooth structures respectively. The aim of the study was to develop a dental handpiece, which guarantees homogeneous fluence at the irradiated tooth surface. Furthermore the point of treatment should be cooled down without energy losses due to the cooling system. We suggest the direct coupling of the laser radiation into a laminar stream of liquid, which may act in turn as a lengthened beam guide. The impacts of the laser radiation and of the cooling medium hit exactly the same point. Hot ablation debris is removed out of the crater by the flush of the water jet. While the surface of a bare fiber working on contact mode is destroyed after a few shots, it was shown that coupling the laser radiation into a stream of liquid prevents this destruction. Putting together the benefits of this special handpiece short overall treatment times seem to be possible. High average power can be applied to the tooth without the threat of thermal damage. Furthermore no time consuming cutting of the fiber prolongs the treatment time.

  19. Thermal Ablation Modeling for Silicate Materials

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq

    2016-01-01

    A general thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in the ablation simulation of the meteoroid and the glassy ablator for spacecraft Thermal Protection Systems. Time-dependent axisymmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. The predicted mass loss rates will be compared with available data for model validation, and parametric studies will also be performed for meteoroid earth entry conditions.

  20. Real-time iterative monitoring of radiofrequency ablation tumor therapy with 15O-water PET imaging.

    PubMed

    Bao, Ande; Goins, Beth; Dodd, Gerald D; Soundararajan, Anuradha; Santoyo, Cristina; Otto, Randal A; Davis, Michael D; Phillips, William T

    2008-10-01

    A method that provides real-time image-based monitoring of solid tumor therapy to ensure complete tumor eradication during image-guided interventional therapy would be a valuable tool. The short, 2-min half-life of (15)O makes it possible to perform repeated PET imaging at 20-min intervals at multiple time points before and after image-guided therapy. In this study, (15)O-water PET was evaluated as a tool to provide real-time feedback and iterative image guidance to rapidly monitor the intratumoral coverage of radiofrequency (RF) ablation therapy. Tumor RF ablation therapy was performed on head and neck squamous cell carcinoma (SCC) xenograft tumors (length, approximately 23 mm) in 6 nude rats. The tumor in each animal was ablated with RF (1-cm active size ablation catheter, 70 degrees C for 5 min) twice in 2 separate tumor regions with a 20-min separation. The (15)O-water PET images were acquired before RF ablation and after the first RF and second RF ablations using a small-animal PET scanner. In each PET session, approximately 100 MBq of (15)O-water in 1.0 mL of saline were injected intravenously into each animal. List-mode PET images were acquired for 7 min starting 20 s before injection. PET images were reconstructed by 2-dimensional ordered-subset expectation maximization into single-frame images and dynamic images at 10 s/frame. PET images were displayed and analyzed with software. Pre-RF ablation images demonstrate that (15)O-water accumulates in tumors with (15)O activity reaching peak levels immediately after administration. After RF ablation, the ablated region had almost zero activity, whereas the unablated tumor tissue continued to have a high (15)O-water accumulation. Using image feedback, the RF probe was repositioned to a tumor region with residual (15)O-water uptake and then ablated. The second RF ablation in this new region of the tumor resulted in additional ablation of the solid tumor, with a corresponding decrease in activity on the (15)O

  1. Complications of Microwave Ablation for Liver Tumors: Results of a Multicenter Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Livraghi, Tito, E-mail: lalivra@tin.it; Meloni, Franca, E-mail: meloni@yahoo.it; Solbiati, Luigi, E-mail: lusolbia@tin.it

    2012-08-15

    Purpose: New technologies for microwave ablation (MWA) have been conceived, designed to achieve larger areas of necrosis compared with radiofrequency ablation (RFA). The purpose of this study was to report complications by using this technique in patients with focal liver cancer. Methods: Members of 14 Italian centers used a 2.45-GMHz generator delivering energy through a cooled miniature-choke MW antenna and a standardized protocol for follow-up. They completed a questionnaire regarding number and type of deaths, major and minor complications and side effects, and likelihood of their relationship to the procedure. Enrollment included 736 patients with 1.037 lesions: 522 had hepatocellularmore » carcinoma with cirrhosis, 187 had metastases predominantly from colorectal cancer, and 27 had cholangiocellular carcinoma. Tumor size ranged from 0.5 to 10 cm. In 13 centers, the approach used was percutaneous, in 4 videolaparoscopic, and in 3 laparotomic. Results: No deaths were reported. Major complications occurred in 22 cases (2.9%), and minor complications in 54 patients (7.3%). Complications of MWA do not differ from those RFA, both being based on the heat damage. Conclusion: Results of this multicenter study confirmed those of single-center experiences, indicating that MWA is a safe procedure, with no mortality and a low rate of major complications. The low rate of complications was probably due to precautions adopted, knowing in advance possible risk conditions, on the basis of prior RFA experience.« less

  2. Laser Ablated Carbon Nanodots for Light Emission.

    PubMed

    Reyes, Delfino; Camacho, Marco; Camacho, Miguel; Mayorga, Miguel; Weathers, Duncan; Salamo, Greg; Wang, Zhiming; Neogi, Arup

    2016-12-01

    The synthesis of fluorescent carbon dots-like nanostructures (CNDs) obtained through the laser ablation of a carbon solid target in liquid environment is reported. The ablation process was induced in acetone with laser pulses of 1064, 532, and 355 nm under different irradiation times. Close-spherical amorphous CNDs with sizes between 5 and 20 nm, whose abundance strongly depends on the ablation parameters were investigated using electron microscopy and was confirmed using absorption and emission spectroscopies. The π- π* electronic transition at 3.76 eV dominates the absorption for all the CNDs species synthesized under different irradiation conditions. The light emission is most efficient due to excitation at 3.54 eV with the photoluminescence intensity centered at 3.23 eV. The light emission from the CNDs is most efficient due to ablation at 355 nm. The emission wavelength of the CNDs can be tuned from the near-UV to the green wavelength region by controlling the ablation time and modifying the ablation and excitation laser wavelength.

  3. Design and Laboratory Validation of a Capacitive Sensor for Measuring the Recession of Thin-Layered Ablator

    NASA Technical Reports Server (NTRS)

    Noffz, Gregory K.; Bowman, Michael P.

    1996-01-01

    Flight vehicles are typically instrumented with subsurface thermocouples to estimate heat transfer at the surface using inverse analysis procedures. If the vehicle has an ablating heat shield, however, temperature time histories from subsurface thermocouples no longer provide enough information to estimate heat flux at the surface. In this situation, the geometry changes and thermal energy leaves the surface in the form of ablation products. The ablation rate is required to estimate heat transfer to the surface. A new concept for a capacitive sensor has been developed to measure ablator depth using the ablator's dielectric effect on a capacitor's fringe region. Relying on the capacitor's fringe region enables the gage to be flush mounted in the vehicle's permanent structure and not intrude into the ablative heat shield applied over the gage. This sensor's design allows nonintrusive measurement of the thickness of dielectric materials, in particular, the recession rates of low-temperature ablators applied in thin (0.020 to 0.060 in. (0.05 to 0.15 mm)) layers. Twenty capacitive gages with 13 different sensing element geometries were designed, fabricated, and tested. A two-dimensional finite-element analysis was performed on several candidate geometries. Calibration procedures using ablator-simulating shims are described. A one-to-one correspondence between system output and dielectric material thickness was observed out to a thickness of 0.055 in. (1.4 mm) for a material with a permittivity about three times that of air or vacuum. A novel method of monitoring the change in sensor capacitance was developed. This technical memorandum suggests further improvements in gage design and fabrication techniques.

  4. Feasibility of Real-Time Intraprocedural Temperature Control during Bone Metastasis Thermal Microwave Ablation: A Bicentric Retrospective Study.

    PubMed

    Kastler, Adrian; Krainik, Alexandre; Sakhri, Linda; Mousseau, Mireille; Kastler, Bruno

    2017-03-01

    To evaluate feasibility of using a thermocouple for temperature monitoring during microwave (MW) ablation of metastatic bone disease. This retrospective study comprised 16 patients (8 men with mean age 63 y and 8 women with mean age 59 y) with 18 bone metastases treated with MW ablation using a thermocouple between March 2012 and October 2015. The mean maximum tumor size was 29.5 mm. MW ablation power was set between 15 W and 40 W and applied for 1-6 minutes. Thermocouple placements were as follows: epidural space (n = 7 cases), nerve roots (n = 9 cases), pleura (n = 1), and pericardium (n = 1). The procedure was considered technically successful when the MW and the thermocouple probes were accurately placed and thermoablation was initiated. Clinical success was defined as a 50% visual analog scale score decrease at 1 month as assessed by the operators. Mean MW ablation time was 4.3 minutes with a mean energy of 30 W. Procedural success was 100%. In 16 cases with neural structure monitoring, temperature did not increase > 43°C. In 8 cases, MW ablation had to be discontinued because of temperature reaching 42°C. Efficacy of the procedure in regard to pain was achieved in 17 of 18 ablation sessions at 1 month. Use of a thermocouple during bone MW ablation is a feasible technique and may be a potentially useful tool to help avoid nontarget ablation surrounding tumors. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

  5. Real-time rotational ICE imaging of the relationship of the ablation catheter tip and the esophagus during atrial fibrillation ablation.

    PubMed

    Helms, Adam; West, J Jason; Patel, Amit; Mounsey, J Paul; DiMarco, John P; Mangrum, J Michael; Ferguson, John D

    2009-02-01

    Atrioesophageal fistula is a rare complication of atrial fibrillation (AF) ablation that should be avoided. We investigated whether rotational intracardiac echocardiography (ICE) can help to minimize ablation close to the esophagus. We studied 41 patients referred for catheter ablation of refractory AF. A rotational ICE catheter was inserted into the (LA) to determine the location of the esophagus. The esophagus was identified to be either adjacent to the pulmonary vein (PV) ostium or to a cuff 2 cm outside the ostium. Circumferential ablation was performed at the PV ostium, with the exact ablation location determined by ICE. The relationship of the catheter tip to the esophagus was imaged during energy delivery, allowing interruption when respiration moved the tip closer to the esophagus. Out of 41 patients, the esophagus was seen near left-sided PVs in 32 and near right-sided PVs in three patients. The median distance from LA endocardium to esophagus was 2.2 mm (range, 1.4-6 mm). In 21 of 35 patients with a closely related esophagus, ablation over the esophagus was avoided by ablating either lateral or medial to the esophagus. In 14 patients, the esophagus could not be avoided, and risk was minimized by limiting lesion size. Significant movement (>10 mm) of the esophagus during the procedure occurred in 3/41 cases. Rotational ICE can accurately determine the distance of ablation sites from the esophagus. Real-time imaging of the relationship of the ablation catheter tip to the esophagus may reduce the incidence of esophageal injury.

  6. Deposition of silicon carbide thin films by pulsed excimer laser ablation technique in the 25-700°C deposition temperature range

    NASA Astrophysics Data System (ADS)

    El Khakani, My A.; Gat, E.; Beaudoin, Yves; Chaker, Mohamed; Monteil, C.; Guay, Daniel; Letourneau, G.; Pepin, Henri

    1995-04-01

    Laser ablation deposition technique was used to deposit silicon carbide thin films on both Si(100) and quartz substrates. The deposition was accomplished by ablating SiC sintered ceramic targets, using a KrF (248 nm) excimer laser. At a laser intensity of about 1 X 109 W/cm2, substrate temperatures in the (25-700) degree(s)C range were investigated. When the deposition temperature is varied from 27 to 650 degree(s)C, (i) the density of a-SiC films increases from 2.6 to 3.0 g cm-3, while their mean roughness value (for a film thickness of about 1 micrometers ) slightly changes from 0.44 to 0.5 nm; (ii) the optical transmission of a-SiC films is significantly improved (the absorption coefficient at 632.8 nm wavelength was reduced by a factor of about 5); and (iii) their Si-C bond density, as determined by FTIR spectroscopy, increases from (13.1 +/- 1.3) to (23.4 +/- 2.4) 1022 bond cm-3. The increased number of Si-C bonds is correlated to the increase of the optical transmission. Over all the investigated deposition temperature range, the a-SiC films were found to be under high compressive stress around a mean value of about 1.26 GPa. The control of the stress of a-SiC films was achieved by means of post- thermal annealings and the annealed a-SiC films were successfully used to fabricate x-ray membranes.

  7. Resin-Impregnated Carbon Ablator: A New Ablative Material for Hyperbolic Entry Speeds

    NASA Technical Reports Server (NTRS)

    Esper, Jaime; Lengowski, Michael

    2012-01-01

    Ablative materials are required to protect a space vehicle from the extreme temperatures encountered during the most demanding (hyperbolic) atmospheric entry velocities, either for probes launched toward other celestial bodies, or coming back to Earth from deep space missions. To that effect, the resin-impregnated carbon ablator (RICA) is a high-temperature carbon/phenolic ablative thermal protection system (TPS) material designed to use modern and commercially viable components in its manufacture. Heritage carbon/phenolic ablators intended for this use rely on materials that are no longer in production (i.e., Galileo, Pioneer Venus); hence the development of alternatives such as RICA is necessary for future NASA planetary entry and Earth re-entry missions. RICA s capabilities were initially measured in air for Earth re-entry applications, where it was exposed to a heat flux of 14 MW/sq m for 22 seconds. Methane tests were also carried out for potential application in Saturn s moon Titan, with a nominal heat flux of 1.4 MW/sq m for up to 478 seconds. Three slightly different material formulations were manufactured and subsequently tested at the Plasma Wind Tunnel of the University of Stuttgart in Germany (PWK1) in the summer and fall of 2010. The TPS integrity was well preserved in most cases, and results show great promise.

  8. Epileptogenicity and pathology - Under consideration of ablative approaches.

    PubMed

    Stefan, H; Schmitt, F C

    2018-05-01

    Besides resective epilepsy surgery, minimally invasive ablation using new diagnostic and therapeutic techniques recently became available. Optimal diagnostic approaches for these treatment options are discussed. The pathophysiology of epileptogenic networks differs depending on the lesion-types and location, requiring a differential use of non-invasive or invasive functional studies. In addition to the definition of epileptogenic zones, a challenge for pre-surgical investigation is the determination of three-dimensional epileptic networks to be removed. Copyright © 2018. Published by Elsevier B.V.

  9. Radiofrequency catheter ablation of idiopathic ventricular arrhythmias originating from intramural foci in the left ventricular outflow tract: efficacy of sequential versus simultaneous unipolar catheter ablation.

    PubMed

    Yamada, Takumi; Maddox, William R; McElderry, H Thomas; Doppalapudi, Harish; Plumb, Vance J; Kay, G Neal

    2015-04-01

    Idiopathic ventricular arrhythmias (VAs) originating from the left ventricular outflow tract (LVOT) sometimes require catheter ablation from the endocardial and epicardial sides for their elimination, suggesting the presence of intramural VA foci. This study investigated the efficacy of sequential and simultaneous unipolar radiofrequency catheter ablation from the endocardial and epicardial sides in treating intramural LVOT VAs. Fourteen consecutive LVOT VAs, which required sequential or simultaneous irrigated unipolar radiofrequency ablation from the endocardial and epicardial sides for their elimination, were studied. The first ablation was performed at the site with the earliest local ventricular activation and best pace map on the endocardial or epicardial side. When the first ablation was unsuccessful, the second ablation was delivered on the other surface. If this sequential unipolar ablation failed, simultaneous unipolar ablation from both sides was performed. The first ablation was performed on the epicardial side in 9 VAs and endocardial side in 5 VAs. The intramural LVOT VAs were successfully eliminated by the sequential (n=9) or simultaneous (n=5) unipolar catheter ablation. Simultaneous ablation was most likely to be required for the elimination of the VAs when the distance between the endocardial and epicardial ablation sites was >8 mm and the earliest local ventricular activation time relative to the QRS onset during the VAs of <-30 ms was recorded at those ablation sites. LVOT VAs originating from intramural foci could usually be eliminated by sequential unipolar radiofrequency ablation and sometimes required simultaneous ablation from both the endocardial and epicardial sides. © 2015 American Heart Association, Inc.

  10. Conjugate Analysis of Two-Dimensional Ablation and Pyrolysis in Rocket Nozzles

    NASA Astrophysics Data System (ADS)

    Cross, Peter G.

    The development of a methodology and computational framework for performing conjugate analyses of transient, two-dimensional ablation of pyrolyzing materials in rocket nozzle applications is presented. This new engineering methodology comprehensively incorporates fluid-thermal-chemical processes relevant to nozzles and other high temperature components, making it possible, for the first time, to rigorously capture the strong interactions and interdependencies that exist between the reacting flowfield and the ablating material. By basing thermal protection system engineering more firmly on first principles, improved analysis accuracy can be achieved. The computational framework developed in this work couples a multi-species, reacting flow solver to a two-dimensional material response solver. New capabilities are added to the flow solver in order to be able to model unique aspects of the flow through solid rocket nozzles. The material response solver is also enhanced with new features that enable full modeling of pyrolyzing, anisotropic materials with a true two-dimensional treatment of the porous flow of the pyrolysis gases. Verification and validation studies demonstrating correct implementation of these new models in the flow and material response solvers are also presented. Five different treatments of the surface energy balance at the ablating wall, with increasing levels of fidelity, are investigated. The Integrated Equilibrium Surface Chemistry (IESC) treatment computes the surface energy balance and recession rate directly from the diffusive fluxes at the ablating wall, without making transport coefficient or unity Lewis number assumptions, or requiring pre-computed surface thermochemistry tables. This method provides the highest level of fidelity, and can inherently account for the effects that recession, wall temperature, blowing, and the presence of ablation product species in the boundary layer have on the flowfield and ablation response. Multiple

  11. Femtosecond laser ablation of enamel

    NASA Astrophysics Data System (ADS)

    Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui

    2016-06-01

    The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

  12. Approaches to catheter ablation for persistent atrial fibrillation.

    PubMed

    Verma, Atul; Jiang, Chen-yang; Betts, Timothy R; Chen, Jian; Deisenhofer, Isabel; Mantovan, Roberto; Macle, Laurent; Morillo, Carlos A; Haverkamp, Wilhelm; Weerasooriya, Rukshen; Albenque, Jean-Paul; Nardi, Stefano; Menardi, Endrj; Novak, Paul; Sanders, Prashanthan

    2015-05-07

    Catheter ablation is less successful for persistent atrial fibrillation than for paroxysmal atrial fibrillation. Guidelines suggest that adjuvant substrate modification in addition to pulmonary-vein isolation is required in persistent atrial fibrillation. We randomly assigned 589 patients with persistent atrial fibrillation in a 1:4:4 ratio to ablation with pulmonary-vein isolation alone (67 patients), pulmonary-vein isolation plus ablation of electrograms showing complex fractionated activity (263 patients), or pulmonary-vein isolation plus additional linear ablation across the left atrial roof and mitral valve isthmus (259 patients). The duration of follow-up was 18 months. The primary end point was freedom from any documented recurrence of atrial fibrillation lasting longer than 30 seconds after a single ablation procedure. Procedure time was significantly shorter for pulmonary-vein isolation alone than for the other two procedures (P<0.001). After 18 months, 59% of patients assigned to pulmonary-vein isolation alone were free from recurrent atrial fibrillation, as compared with 49% of patients assigned to pulmonary-vein isolation plus complex electrogram ablation and 46% of patients assigned to pulmonary-vein isolation plus linear ablation (P=0.15). There were also no significant differences among the three groups for the secondary end points, including freedom from atrial fibrillation after two ablation procedures and freedom from any atrial arrhythmia. Complications included tamponade (three patients), stroke or transient ischemic attack (three patients), and atrioesophageal fistula (one patient). Among patients with persistent atrial fibrillation, we found no reduction in the rate of recurrent atrial fibrillation when either linear ablation or ablation of complex fractionated electrograms was performed in addition to pulmonary-vein isolation. (Funded by St. Jude Medical; ClinicalTrials.gov number, NCT01203748.).

  13. Contrast-enhanced harmonic ultrasound imaging in ablation therapy for primary hepatocellular carcinoma.

    PubMed

    Minami, Yasunori; Kudo, Masatoshi

    2009-12-31

    The success rate of percutaneous radiofrequency (RF) ablation for hepatocellular carcinoma (HCC) depends on correct targeting via an imaging technique. However, RF electrode insertion is not completely accurate for residual HCC nodules because B-mode ultrasound (US), color Doppler, and power Doppler US findings cannot adequately differentiate between treated and viable residual tumor tissue. Electrode insertion is also difficult when we must identify the true HCC nodule among many large regenerated nodules in cirrhotic liver. Two breakthroughs in the field of US technology, harmonic imaging and the development of second-generation contrast agents, have recently been described and have demonstrated the potential to dramatically broaden the scope of US diagnosis of hepatic lesions. Contrast-enhanced harmonic US imaging with an intravenous contrast agent can evaluate small hypervascular HCC even when B-mode US cannot adequately characterize tumor. Therefore, contrast-enhanced harmonic US can facilitate RF ablation electrode placement in hypervascular HCC, which is poorly depicted by B-mode US. The use of contrast-enhanced harmonic US in ablation therapy for liver cancer is an efficient approach.

  14. Ablative therapies: Advantages and disadvantages of radiofrequency, cryotherapy, microwave and electroporation methods, or how to choose the right method for an individual patient?

    PubMed

    Seror, O

    2015-06-01

    Several ablation techniques are currently available. Except for electroporation, all of these methods cause fatal damage at a cellular level and irreversible architectural deconstruction at a tissue level by thermal effects. Ablation of a tumor using one of these techniques, whether thermal or otherwise, requires applicators to be positioned from which the energy is delivered in situ. Some techniques, however, require several applicators to be inserted (multibipolar radiofrequency, cryotherapy and electroporation) whereas a single applicator is often sufficient with other technologies (monopolar radiofrequency and microwave). These methods are conceptually very similar but are distinguished from each other in practice through the technologies they use. It is essential to understand these differences as they influence the advantages and limitations of each of the techniques. There is no such thing as the perfect multifunctional ablation device and choice is dictated on an individual patient basis depending on the aim of treatment, which itself depends on each patient's clinical situation. Copyright © 2015 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  15. Determining Distributed Ablation over Dirty Ice Areas of Debris-covered Glaciers Using a UAV-SfM Approach

    NASA Astrophysics Data System (ADS)

    Woodget, A.; Fyffe, C. L.; Kirkbride, M. P.; Deline, P.; Westoby, M.; Brock, B. W.

    2017-12-01

    Dirty ice areas (where debris cover is discontinuous) are often found on debris-covered glaciers above the limit of continuous debris and are important because they are areas of high melt and have been recognized as the locus of the identified upglacier increase in debris cover. The modelling of glacial ablation in areas of dirty ice is in its infancy and is currently restricted to theoretical studies. Glacial ablation is traditionally determined at point locations using stakes drilled into the ice. However, in areas of dirty ice, ablation is highly spatially variable, since debris a few centimetres thick is near the threshold between enhancing and reducing ablation. As a result, it is very difficult to ascertain if point ablation measurements are representative of ablation of the area surrounding the stake - making these measurements unsuitable for the validation of models of dirty ice ablation. This paper aims to quantify distributed ablation and its relationship to essential dirty ice characteristics with a view to informing the construction of dirty ice melt models. A novel approach to determine distributed ablation is presented which uses repeat aerial imagery acquired from a UAV (Unmanned Aerial Vehicle), processed using SfM (Structure from Motion) techniques, on an area of dirty ice on Miage Glacier, Italian Alps. A spatially continuous ablation map is presented, along with a correlation to the local debris characteristics. Furthermore, methods are developed which link ground truth data on the percentage debris cover, albedo and clast depth to the UAV imagery, allowing these characteristics to be determined for the entire study area, and used as model inputs. For example, debris thickness is determined through a field relationship with clast size, which is then correlated with image texture and point cloud roughness metrics derived from the UAV imagery. Finally, we evaluate the potential of our novel approach to lead to improved modelling of dirty ice

  16. Outcomes of Cryoballoon Ablation in High- and Low-Volume Atrial Fibrillation Ablation Centres: A Russian Pilot Survey

    PubMed Central

    Mikhaylov, Evgeny N.; Lebedev, Dmitry S.; Pokushalov, Evgeny A.; Davtyan, Karapet V.; Ivanitskii, Eduard A.; Nechepurenko, Anatoly A.; Kosonogov, Alexey Ya.; Kolunin, Grigory V.; Morozov, Igor A.; Termosesov, Sergey A.; Maykov, Evgeny B.; Khomutinin, Dmitry N.; Eremin, Sergey A.; Mayorov, Igor M.; Romanov, Alexander B.; Shabanov, Vitaliy V.; Shatakhtsyan, Victoria; Tsivkovskii, Viktor; Revishvili, Amiran Sh.; Shlyakhto, Evgeny V.

    2015-01-01

    Purpose. The results of cryoballoon ablation (CBA) procedure have been mainly derived from studies conducted in experienced atrial fibrillation (AF) ablation centres. Here, we report on CBA efficacy and complications resulting from real practice of this procedure at both high- and low-volume centres. Methods. Among 62 Russian centres performing AF ablation, 15 (24%) used CBA technology for pulmonary vein isolation. The centres were asked to provide a detailed description of all CBA procedures performed and complications, if encountered. Results. Thirteen sites completed interviews on all CBAs in their centres (>95% of CBAs in Russia). Six sites were high-volume AF ablation (>100 AF cases/year) centres, and 7 were low-volume AF ablation. There was no statistical difference in arrhythmia-free rates between high- and low-volume centres (64.6 versus 60.8% at 6 months). Major complications developed in 1.5% of patients and were equally distributed between high- and low-volume centres. Minor procedure-related events were encountered in 8% of patients and were more prevalent in high-volume centres. Total event and vascular access site event rates were higher in women than in men. Conclusions. CBA has an acceptable efficacy profile in real practice. In less experienced AF ablation centres, the major complication rate is equal to that in high-volume centres. PMID:26640789

  17. Thrust Measurements in Ballistic Pendulum Ablative Laser Propulsion Experiments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brazolin, H.; Rodrigues, N. A. S.; Minucci, M. A. S.

    This paper describes a setup for thrust measurement in ablative laser propulsion experiments, based on a simple ballistic pendulum associated to an imaging system, which is being assembled at IEAv. A light aluminium pendulum holding samples is placed inside a 100 liters vacuum chamber with two optical windows: the first (in ZnSe) for the laser beam and the second (in fused quartz) for the pendulum visualization. A TEA-CO{sub 2} laser beam is focused to the samples providing ablation and transferring linear moment to the pendulum as a whole. A CCD video camera captures the oscillatory movement of the pendulum andmore » the its trajectory is obtained by image processing. By fitting the trajectory of the pendulum to a dumped sinusoidal curve is possible to obtain the amplitude of the movement which is directly related to the momentum transfered to the sample.« less

  18. Focal Hydrothermal Ablation: Preliminary Investigation of a New Concept

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roy, Sumit, E-mail: sumit.roy@online.no

    2013-08-01

    PurposeTo determine whether focal tissue ablation is possible with interstitial instillation of steam.MethodsFresh swine livers were used. Through a 20 gauge needle, steam was instilled every 5 s, 3 (n = 5), 6 (n = 5), 9 (n = 5), or 12 (n = 5 + 5) times in a liver lobe. The ablated zones were sectioned parallel (n = 20) or perpendicular (n = 5) to the needle track. The longitudinal long and short axis diameters, or transverse long and short axis diameters of areas with discoloration on macroscopic examination, were measured. The experiment was repeated in vivo onmore » a pig. Steam instillation was performed once every 5 s for 5 min in the liver (n = 3) and in muscle (n = 4), and temperature changes at three neighboring sites were monitored. Long and short axis diameters of the discolored areas were measured.ResultsA well-defined area of discoloration was invariably present at the site of steam instillation. The median longitudinal long axis diameter were 2.0, 2.5, 2.5, and 3.5 cm for 3, 6, 9, and 12 steam instillations in vitro, while median short axis diameters were 1.0, 1.5, 1.5, and 1.5 cm, respectively. Six attempts at ablation in vivo could be successfully completed. The long axis diameters of the ablated zones in the liver were 7.0 and 8.0 cm, while in muscle it ranged from 5.5 to 7.0 cm.ConclusionInstillation of steam in the liver in vitro and in vivo, and in muscle in vivo rapidly leads to circumscribed zones of coagulation necrosis.« less

  19. Microembolism and catheter ablation I: a comparison of irrigated radiofrequency and multielectrode-phased radiofrequency catheter ablation of pulmonary vein ostia.

    PubMed

    Haines, David E; Stewart, Mark T; Dahlberg, Sarah; Barka, Noah D; Condie, Cathy; Fiedler, Gary R; Kirchhof, Nicole A; Halimi, Franck; Deneke, Thomas

    2013-02-01

    Cerebral diffusion-weighted MRI lesions have been observed after catheter ablation of atrial fibrillation. We hypothesized that conditions predisposing to microembolization could be identified using a porcine model of pulmonary vein ablation and an extracorporeal circulation loop. Ablations of the pulmonary veins were performed in 18 swine with echo monitoring. The femoral artery and vein were cannulated and an extracorporeal circulation loop with 2 ultrasonic bubble detectors and a 73-μm filter were placed in series. Microemboli and microbubbles were compared between ablation with an irrigated radiofrequency system (Biosense-Webster) and a phased radiofrequency multielectrode system (pulmonary vein ablation catheter [PVAC], Medtronic, Inc, Carlsbad, CA) in unipolar and 3 blended unipolar/bipolar modes. Animal pathology was examined. The size and number of microbubbles observed during ablation ranged from 30 to 180 μm and 0 to 3253 bubbles per ablation. Microbubble volumes with PVAC (29.1 nL) were greater than with irrigated radiofrequency (0.4 nL; P=0.045), and greatest with type II or III microbubbles on transesophageal echocardiography. Ablation with the PVAC showed fewest microbubbles in the unipolar mode (P=0.012 versus bipolar). The most occurred during bipolar energy delivery with overlap of proximal and distal electrodes (median microbubble volume, 1744 nL; interquartile range, 737-4082 nL; maximum, 19 516 nL). No cerebral MRI lesions were seen, but 2 animals had renal embolization. Left atrial ablation with irrigated radiofrequency and PVAC catheters in swine is associated with microbubble and microembolus production. Avoiding overlap of electrodes 1 and 10 on PVAC should reduce the microembolic burden associated with this procedure.

  20. Electromagnetic Tracking Navigation to Guide Radiofrequency Ablation (RFA) of a Lung Tumor

    PubMed Central

    Amalou, Hayet; Wood, Bradford J.

    2013-01-01

    Radiofrequency ablation (RFA) may be an option for patients with lung tumors who have unresectable disease and are not suitable for available palliative modalities. RFA electrode positioning may take several attempts, necessitating multiple imaging acquisitions or continuous use of CT (Computed Tomography). Electromagnetic tracking utilizes miniature sensors integrated with RFA equipment to guide tools in real-time, while referencing to pre-procedure imaging. This technology was demonstrated successfully during a lung tumor ablation, and was more accurate at targeting the tumor, compared to traditional freehand needle insertion. It is possible, although speculative and anecdotal, that more accuracy could prevent unnecessary repositioning punctures and decrease radiation exposure. Electromagnetic tracking has theoretical potential to benefit minimally invasive interventions. PMID:23207535

  1. Radiofrequency thermo-ablation of PVNS in the knee: initial results.

    PubMed

    Lalam, Radhesh K; Cribb, Gillian L; Cassar-Pullicino, Victor N; Cool, Wim P; Singh, Jaspreet; Tyrrell, Prudencia N M; Tins, Bernhard J; Winn, Naomi

    2015-12-01

    Pigmented villonodular synovitis (PVNS) is normally treated by arthroscopic or open surgical excision. We present our initial experience with radiofrequency thermo-ablation (RF ablation) of PVNS located in an inaccessible location in the knee. Review of all patients with histologically proven PVNS treated with RF ablation and with at least 2-year follow-up. Three patients met inclusion criteria and were treated with RF ablation. Two of the patients were treated successfully by one ablation procedure. One of the three patients had a recurrence which was also treated successfully by repeat RF ablation. There were no complications and all patients returned to their previous occupations following RF ablation. In this study we demonstrated the feasibility of performing RF ablation to treat PVNS in relatively inaccessible locations with curative intent. We have also discussed various post-ablation imaging appearances which can confound the assessment for residual/recurrent disease.

  2. Improved recovery of Listeria monocytogenes from stainless steel and polytetrafluoroethylene surfaces using air/water ablation.

    PubMed

    Gião, M S; Blanc, S; Porta, S; Belenguer, J; Keevil, C W

    2015-07-01

    To develop a gentle ablation technique to recover Listeria monocytogenes biofilms from stainless steel (SS) and polytetrafluoroethylene (PTFE) surfaces by using compressed air and water injection. Biofilms were grown for 4, 24 and 48 h or 7 days and a compressed air and water flow at 2, 3 and 4 bars was applied for cell removal. Collected cells were quantified for total/dead by staining with SYTO 9/PI double staining and cultivable populations were determined by plating onto brain heart infusion (BHI) agar, while coupon surfaces also were stained with DAPI to quantify in situ the remaining cells. The recovery efficiency was compared to that of conventional swabbing. Results showed that the air/water ablation is able to collect up to 98·6% of cells from SS surfaces while swabbing only recovered 11·2% of biofilm. Moreover, air/water ablation recovered 99·9% of cells from PTFE surfaces. The high recovery rate achieved by this technique, along with the fact that cells were able to retain membrane integrity and cultivability, indicate that this device is suitable for the gentle recovery of viable L. monocytogenes biofilm cells. This work presents a highly efficient technique to remove, collect and quantify L. monocytogenes from surfaces commonly used in the food industry, which can thus serve as an important aid in verifying cleaning and sanitation as well as in reducing the likelihood of cross-contamination events. © 2015 The Society for Applied Microbiology.

  3. Ellipsometric study of YBa2Cu3O(7-x) laser ablated and co-evaporated films

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Sieg, R. E.; Warner, J. D.; Stan, M. A.; Vitta, S.

    1990-01-01

    High temperature superconducting films of YBa2Cu3O(7-x) (YBCO were grown on SrTiO3, LaA1O3, and YSZ substrates using two techniques: excimer laser ablation with in situ annealing and co-evaporation of Y, Cu, and BaF2 with ex-situ annealing. Film thicknesses were typically 5000 A, with predominant c-axis alignment perpendicular to the substrate. Critical temperatures up to Tc(R=O)=90 K were achieved by both techniques. Ellipsometric measurements were taken in the range 1.6 to 4.3 eV using a variable angle spectroscopic ellipsometer. The complex dielectric function of the laser ablated films was reproducible from run to run, and was found to be within 10 percent of that previously reported for (001) oriented single crystals. A dielectric overlayer was observed in these films, with an index of refraction of approximately 1.55 and nearly zero absorption. For the laser ablated films the optical properties were essentially independent of substrate material. The magnitude of the dielectric function obtained for the co-evaported films was much lower than the value reported for single crystals, and was sample dependent.

  4. Novel Laser Ablation Technology for Surface Decontamination

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheng, Chung H.

    2004-06-01

    Laser ablation for surface cleaning has been pursued for the removal of paint on airplanes. It has also been pursued for the cleaning of semiconductor surfaces. However, all these approaches have been pursued by laser ablation in air. For highly contaminated surface, laser ablation in air can easily cause secondary contamination. Thus it is not suitable to apply to achieve surface decontamination for DOE facilities since many of these facilities have radioactive contaminants on the surface. Any secondary contamination will be a grave concern. The objective of this project is to develop a novel technology for laser ablation in liquidmore » for surface decontamination. It aims to achieve more efficient surface decontamination without secondary contamination and to evaluate the economic feasibility for large scale surface decontamination with laser ablation in liquid. When laser ablation is pursued in the solution, all the desorbed contaminants will be confined in liquid. The contaminants can be precipitated and subsequently contained in a small volume for disposal. It can reduce the risk of the decontamination workers. It can also reduce the volume of contaminants dramatically.« less

  5. Improvement of ablative margins by the intraoperative use of CEUS-CT/MR image fusion in hepatocellular carcinoma.

    PubMed

    Li, Kai; Su, Zhong-Zhen; Xu, Er-Jiao; Ju, Jin-Xiu; Meng, Xiao-Chun; Zheng, Rong-Qin

    2016-04-18

    To assess whether intraoperative use of contrast-enhanced ultrasound (CEUS)-CT/MR image fusion can accurately evaluate ablative margin (AM) and guide supplementary ablation to improve AM after hepatocellular carcinoma (HCC) ablation. Ninety-eight patients with 126 HCCs designated to undergo thermal ablation treatment were enrolled in this prospective study. CEUS-CT/MR image fusion was performed intraoperatively to evaluate whether 5-mm AM was covered by the ablative area. If possible, supplementary ablation was applied at the site of inadequate AM. The CEUS image quality, the time used for CEUS-CT/MR image fusion and the success rate of image fusion were recorded. Local tumor progression (LTP) was observed during follow-up. Clinical factors including AM were examined to identify risk factors for LTP. The success rate of image fusion was 96.2% (126/131), and the duration required for image fusion was 4.9 ± 2.0 (3-13) min. The CEUS image quality was good in 36.1% (53/147) and medium in 63.9% (94/147) of the cases. By supplementary ablation, 21.8% (12/55) of lesions with inadequate AMs became adequate AMs. During follow-up, there were 5 LTPs in lesions with inadequate AMs and 1 LTP in lesions with adequate AMs. Multivariate analysis showed that AM was the only independent risk factor for LTP (hazard ratio, 9.167; 95% confidence interval, 1.070-78.571; p = 0.043). CEUS-CT/MR image fusion is feasible for intraoperative use and can serve as an accurate method to evaluate AMs and guide supplementary ablation to lower inadequate AMs.

  6. Comparison of the Three NIF Ablators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kritcher, A. L.; Clark, D. S.; Haan, S. W.

    Indirect drive implosion experiments on NIF have now been performed using three different ablator materials: glow discharge polymer (GDP) or CH, high density carbon (HDC, which we also refer to as diamond), and sputtered beryllium (Be). It has been appreciated for some time that each of these materials has specific advantages and disadvantages as an ICF ablator.[1-4] In light of experiments conducted on NIF in the last few years, how do these ablators compare? Given current understanding, is any ablator more or less likely to reach ignition on NIF? Has the understanding of their respective strengths and weaknesses changed sincemore » NIF experiments began? How are those strengths and weaknesses highlighted by implosion designs currently being tested or planned for testing soon? This document aims to address these questions by combining modern simulation results with a survey of the current experimental data base. More particularly, this document is meant to fulfill an L2 Milestone for FY17 to “Document our understanding of the relative advantages and disadvantages of CH, HDC, and Be designs.” Note that this document does not aim to recommend a down-selection of the current three ablator choices. It is intended only to gather and document the current understanding of the differences between these ablators and thereby inform the choices made in planning future implosion experiments. This document has two themes: (i) We report on a reanalysis project in which post-shot simulations were done on a common basis for layered shots using each ablator. This included data from keyholes, 2D ConA, and so forth, from each campaign, leading up to the layered shots. (“Keyholes” are shots dedicated to measuring the shock timing in a NIF target, as described in Ref. 5. “2DConAs” are backlit implosions in which the symmetry of the implosion is measured between about half and full convergence, as described in Ref. 6.) This set of common-basis postshot simulations is

  7. Efficiency of planetesimal ablation in giant planetary envelopes

    NASA Astrophysics Data System (ADS)

    Pinhas, Arazi; Madhusudhan, Nikku; Clarke, Cathie

    2016-12-01

    Observations of exoplanetary spectra are leading to unprecedented constraints on their atmospheric elemental abundances, particularly O/H, C/H, and C/O ratios. Recent studies suggest that elemental ratios could provide important constraints on formation and migration mechanisms of giant exoplanets. A fundamental assumption in such studies is that the chemical composition of the planetary envelope represents the sum-total of compositions of the accreted gas and solids during the formation history of the planet. We investigate the efficiency with which accreted planetesimals ablate in a giant planetary envelope thereby contributing to its composition rather than sinking to the core. From considerations of aerodynamic drag causing `frictional ablation' and the envelope temperature structure causing `thermal ablation', we compute mass ablations for impacting planetesimals of radii 30 m to 1 km for different compositions (ice to iron) and a wide range of velocities and impact angles, assuming spherical symmetry. Icy impactors are fully ablated in the outer envelope for a wide range of parameters. Even for Fe impactors substantial ablation occurs in the envelope for a wide range of sizes and velocities. For example, iron impactors of sizes below ˜0.5 km and velocities above ˜30 km s-1 are found to ablate by ˜60-80 per cent within the outer envelope at pressures below 103 bar due to frictional ablation alone. For deeper pressures (˜107 bar), substantial ablation happens over a wider range of parameters. Therefore, our exploratory study suggests that atmospheric abundances of volatile elements in giant planets reflect their accretion history during formation.

  8. Investigations on laser hard tissue ablation under various environments

    NASA Astrophysics Data System (ADS)

    Kang, H. W.; Oh, J.; Welch, A. J.

    2008-06-01

    The purpose of this study was to investigate the effect of liquid environments upon laser bone ablation. A long-pulsed Er,Cr:YSGG laser was employed to ablate bovine bone tibia at various radiant exposures under dry, wet (using water or perfluorocarbon) and spray environmental conditions. Energy loss by the application of liquid during laser irradiation was evaluated, and ablation performance for all conditions was quantitatively measured by optical coherence tomography (OCT). Microscope images were also used to estimate thermal side effects in tissue after multiple-pulse ablation. Wet using water and spray conditions equally attenuated the 2.79 µm wavelength laser beam. Higher transmission efficiency was obtained utilizing a layer of perfluorocarbon. Dry ablation exhibited severe carbonization due to excessive heat accumulation. Wet condition using water resulted in similar ablation volume to the dry case without carbonization. The perfluorocarbon layer produced the largest ablation volume but some carbonization due to the poor thermal conductivity. Spray induced clean cutting with slightly reduced efficiency. Liquid-assisted ablation provided significant beneficial effects such as augmented material removal and cooling/cleaning effects during laser osteotomy.

  9. High-intensity interstitial ultrasound for thermal ablation of focal cancer targets in prostate

    NASA Astrophysics Data System (ADS)

    Salgaonkar, Vasant A.; Scott, Serena; Kurhanewicz, John; Diederich, Chris J.

    2017-03-01

    Recent advances in image based techniques such as multi-parametric MRI (MP-MRI) can provide precise targeting of focal disease in the prostate. Thermal ablation of such cancer targets while avoiding rectum, urethra, neurovascular bundles (NVB) and sphincter is clinically challenging. The approach described here employs multi-element ultrasound linear arrays designed for transperineal placement within prostate. They consist of independently powered sectored tubular transducers (6.5 - 8.0 MHz) that provide spatial control of energy deposition in angle and length. Volumetric ablation strategies were investigated through patient-specific biothermal models based on Pennes bioheat transfer equation. The acoustic and heat transfer models used here have been validated in several previous simulation and experimental studies. Focal disease sites in prostate were identified through multi-parametric MR images of representative patient cases (n=3). Focal cancer lesions and critical anatomy (prostate, urethra, rectum, bladder, seminal vesicles) were manually segmented (Mimics, Materialise) and converted to 3D finite element meshes (3-Matic, Materialise). The chosen test cases consisted of patients with medium and large sized glands and models of bulk tissue ablation covered volumes in a single quadrant in posterior prostate, hemi-gland targets and "hockey-stick" targets (lesions in three quadrants). Ultrasound applicator placement was determined such that devices were positioned along the prostate periphery while avoiding surrounding anatomy. Transducer sector angles were chosen based on applicator location within limits of fabrication practicability. Thermal models were numerically solved using finite element methods (FEM) in COMSOL Multiphysics. Temperature and thermal dose distributions were calculated to determine treated volumes (> 240 CEM43C, >52 °C) and safety profiles (<10 CEM43C, <45 °C) for nerve, rectal and urethral sparing. Modeling studies indicated that focal

  10. How to perform posterior wall isolation in catheter ablation for atrial fibrillation.

    PubMed

    Sugumar, Hariharan; Thomas, Stuart P; Prabhu, Sandeep; Voskoboinik, Aleksandr; Kistler, Peter M

    2018-02-01

    Catheter ablation has become standard of care in patients with symptomatic atrial fibrillation (AF). Although there have been significant advances in our understanding and technology, a substantial proportion of patients have ongoing AF requiring repeat procedures. Pulmonary vein isolation (PVI) is the cornerstone of AF ablation; however, it is less effective in patients with persistent as opposed to paroxysmal atrial fibrillation. Left atrial posterior wall isolation (PWI) is commonly performed as an adjunct to PVI in patients with persistent AF with nonrandomized studies showing improved outcomes. Anatomical considerations and detailed outline of the various approaches and techniques to performing PWI are detailed, and advantages and pitfalls to assist the clinical electrophysiologist successfully and safely complete PWI are described. © 2017 Wiley Periodicals, Inc.

  11. Femtosecond laser ablation of the stapes

    NASA Astrophysics Data System (ADS)

    McCaughey, Ryan G.; Sun, Hui; Rothholtz, Vanessa S.; Juhasz, Tibor; Wong, Brian J. F.

    2009-03-01

    A femtosecond laser, normally used for LASIK eye surgery, is used to perforate cadaveric human stapes. The thermal side effects of bone ablation are measured with a thermocouple in an inner ear model and are found to be within acceptable limits for inner ear surgery. Stress and acoustic events, recorded with piezoelectric film and a microphone, respectively, are found to be negligible. Optical microscopy, scanning electron microscopy, and optical coherence tomography are used to confirm the precision of the ablation craters and lack of damage to the surrounding tissue. Ablation is compared to that from an Er:YAG laser, the current laser of choice for stapedotomy, and is found to be superior. Ultra-short-pulsed lasers offer a precise and efficient ablation of the stapes, with minimal thermal and negligible mechanical and acoustic damage. They are, therefore, ideal for stapedotomy operations.

  12. Monitoring radiofrequency ablation with ultrasound Nakagami imaging.

    PubMed

    Wang, Chiao-Yin; Geng, Xiaonan; Yeh, Ta-Sen; Liu, Hao-Li; Tsui, Po-Hsiang

    2013-07-01

    Radiofrequency ablation (RFA) is a widely used alternative modality in the treatment of liver tumors. Ultrasound B-mode imaging is an important tool to guide the insertion of the RFA electrode into the tissue. However, it is difficult to visualize the ablation zone because RFA induces the shadow effect in a B-scan. Based on the randomness of ultrasonic backscattering, this study proposes ultrasound Nakagami imaging, which is a well-established method for backscattered statistics analysis, as an approach to complement the conventional B-scan for evaluating the ablation region. Porcine liver samples (n = 6) were ablated using a RFA system and monitored by employing an ultrasound scanner equipped with a 7.5 MHz linear array transducer. During the stages of ablation (0-12 min) and postablation (12-24 min), the raw backscattered data were acquired at a sampling rate of 30 MHz for B-mode, Nakagami imaging, and polynomial approximation of Nakagami imaging. The contrast-to-noise ratio (CNR) was also calculated to compare the image contrasts of the B-mode and Nakagami images. The results demonstrated that the Nakagami image has the ability to visualize changes in the backscattered statistics in the ablation zone, including the shadow region during RFA. The average Nakagami parameter increased from 0.2 to 0.6 in the ablation stage, and then decreased to approximately 0.3 at the end of the postablation stage. Moreover, the CNR of the Nakagami image was threefold that of the B-mode image, showing that the Nakagami image has a better image contrast for monitoring RFA. Specifically, the use of the polynomial approximation equips the Nakagami image with an enhanced ability to estimate the range of the ablation region. This study demonstrated that ultrasound Nakagami imaging based on the analysis of backscattered statistics has the ability to visualize the RFA-induced ablation zone, even if the shadow effect exists in the B-scan.

  13. Caring for women undergoing cardiac ablation.

    PubMed

    Keegan, Beryl

    2008-09-01

    Radiofrequency cardiac ablation (RFCA) has become the treatment of choice for many cardiac arrhythmias that have not responded to medication. Complications of cardiac ablation include bleeding, thrombosis, pericardial tamponade, and stroke. Many complications are procedure specific, and several complications can be avoided with appropriate nursing care. Quality patient outcomes begin with competent nursing care. Therefore it is vital for a patient undergoing a percutaneous cardiac ablation procedure to receive supportive care and pre- and post-interventional patient education. This article discusses the nursing care of women undergoing RFCA.

  14. Study of Mn laser ablation in methane atmosphere

    NASA Astrophysics Data System (ADS)

    Krstulović, N.; Labazan, I.; Milošević, S.

    2006-02-01

    Laser ablation of Mn target in vacuum and in the presence of CH4 was studied under 308 nm laser irradiation. Time-resolved emission using gated detection and scanning monochromator and absorption using the cavity ring-down spectroscopy were used to study vaporized plume. In the CH4 atmosphere we observed transitions identified as C2 and MnH bands, while these spectral features were not detected in emission spectra. This is a clear evidence of importance in combining both spectroscopic techniques in laser vaporized plume study.

  15. Catheter ablation in patients with persistent atrial fibrillation

    PubMed Central

    Kirchhof, Paulus; Calkins, Hugh

    2017-01-01

    Catheter ablation is increasingly offered to patients who suffer from symptoms due to atrial fibrillation (AF), based on a growing body of evidence illustrating its efficacy compared with antiarrhythmic drug therapy. Approximately one-third of AF ablation procedures are currently performed in patients with persistent or long-standing persistent AF. Here, we review the available information to guide catheter ablation in these more chronic forms of AF. We identify the following principles: Our clinical ability to discriminate paroxysmal and persistent AF is limited. Pulmonary vein isolation is a reasonable and effective first approach for catheter ablation of persistent AF. Other ablation strategies are being developed and need to be properly evaluated in controlled, multicentre trials. Treatment of concomitant conditions promoting recurrent AF by life style interventions and medical therapy should be a routine adjunct to catheter ablation of persistent AF. Early rhythm control therapy has a biological rationale and trials evaluating its value are underway. There is a clear need to generate more evidence for the best approach to ablation of persistent AF beyond pulmonary vein isolation in the form of adequately powered controlled multi-centre trials. PMID:27389907

  16. Investigation of the wavelength dependence of laser stratigraphy on Cu and Ni coatings using LIBS compared to a pure thermal ablation model

    NASA Astrophysics Data System (ADS)

    Paulis, Evgeniya; Pacher, Ulrich; Weimerskirch, Morris J. J.; Nagy, Tristan O.; Kautek, Wolfgang

    2017-12-01

    In this study, galvanic coatings of Cu and Ni, typically applied in industrial standard routines, were investigated. Ablation experiments were carried out using the first two harmonic wavelengths of a pulsed Nd:YAG laser and the resulting plasma spectra were analysed using a linear Pearson correlation method. For both wavelengths the absorption/ablation behaviour as well as laser-induced breakdown spectroscopy (LIBS) depth profiles were studied varying laser fluences between 4.3-17.2 J/cm^2 at 532 nm and 2.9-11.7 J/cm^2 at 1064 nm. The LIBS-stratigrams were compared with energy-dispersive X-ray spectroscopy of cross-sections. The ablation rates were calculated and compared to theoretical values originating from a thermal ablation model. Generally, higher ablation rates were obtained with 532 nm light for both materials. The light-plasma interaction is suggested as possible cause of the lower ablation rates in the infrared regime. Neither clear evidence of the pure thermal ablation, nor correlation with optical properties of investigated materials was obtained.

  17. Partial ablation of Ti/Al nano-layer thin film by single femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Gaković, B.; Tsibidis, G. D.; Skoulas, E.; Petrović, S. M.; Vasić, B.; Stratakis, E.

    2017-12-01

    The interaction of ultra-short laser pulses with Titanium/Aluminium (Ti/Al) nano-layered thin film was investigated. The sample composed of alternating Ti and Al layers of a few nanometres thick was deposited by ion-sputtering. A single pulse irradiation experiment was conducted in an ambient air environment using focused and linearly polarized femtosecond laser pulses for the investigation of the ablation effects. The laser induced morphological changes and the composition were characterized using several microscopy techniques and energy dispersive X-ray spectroscopy. The following results were obtained: (i) at low values of pulse energy/fluence, ablation of the upper Ti layer only was observed; (ii) at higher laser fluence, a two-step ablation of Ti and Al layers takes place, followed by partial removal of the nano-layered film. The experimental observations were supported by a theoretical model accounting for the thermal response of the multiple layered structure upon irradiation with ultra-short laser pulses.

  18. Radiofrequency Ablation in Combination with Embolization in Metachronous Recurrent Renal Cancer in Solitary Kidney after Contralateral Tumor Nephrectomy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gebauer, Bernhard, E-mail: bernhard.gebauer@charite.de; Werk, Michael; Lopez-Haenninen, Enrique

    Purpose. To evaluate the feasibility and safety of minimally invasive, percutaneous techniques in metachronous recurrent renal cell cancers (RCCs) in solitary kidneys. Methods. In 4 patients, recurrent RCC was treated by radiofrequency ablation (RFA) (RITA, StarBurst) alone, and in 2 patients by RFA in combination with superselective transarterial particle-lipiodol embolization using 3 Fr microcatheters. RFA was guided by computed tomography in 5 patients, and by magnetic resonance imaging in 1 patient. Mean tumor diameter was 26.7 mm (range 10-45 mm). All interventions were technically successful; during follow-up 1 patient developed recurrent RCC, which was retreated by RFA after embolization. Results.more » No major peri- or postprocedural complications occurred. Changes in creatinine (pre- vs. post-intervention, 122 vs. 127 {mu}mol/l) and calculated creatinine clearance (pre- vs. post-intervention, 78 vs. 73 ml/min) after ablation were minimal. Conclusion. In single kidneys, percutaneous, minimally invasive techniques are safe and feasible. In large tumors, or where there are adjacent critical structures, we prefer a combination of embolization and thermal ablation (RFA)« less

  19. Radiofrequency ablation for treatment of sporadic angiomyolipoma.

    PubMed

    Prevoo, Warner; van den Bosch, Maurice A A J; Horenblas, Simon

    2008-07-01

    Symptomatic angiomyolipoma (AML) and asymptomatic AML larger than 4 cm in size are usually treated with nephron-sparing surgery or arterial embolization. We used another technique, that is, radiofrequency ablation (RFA), for treatment of a sporadic AML in a patient with a solitary kidney, in whom maximal sparing of normal renal tissue was required. Contrast-enhanced computed tomography (CT) showed an enhancing well-defined mainly lipomatous tumor, with a maximum diameter of 4.5 cm in the upper pole of the left kidney. Diagnosis of AML was confirmed with fine-needle aspiration biopsy. RFA was performed with a RF 3000 system, consisting of a generator that supplied up to 200W of power, connected to a 15-gauge LeVeen multipolar array electrode that was placed under CT-guidance centrally in the AML. Initial power was set at low power and increased with increments of 10W, according to the algorithm provided by the manufacturer, resulting in a final tumor end temperature above 65 degrees C. No complications occurred and the patient was discharged home the day after. During follow-up (12 months) function of the solitary kidney of the patient was preserved and patient did not have any AML-related symptoms develop. Contrast-enhanced CT scan showed complete (100%) tumor ablation with absence of enhancement in the tumor and decreased tumor size from 4.5 cm to 2.9 cm at 12 months. CT-guided RFA is a minimally invasive ablation procedure that allowed successful treatment of a sporadic AML in a patient with a solitary kidney. No complications occurred and no AML recurrence was observed during the 12-month follow-up.

  20. Influence of large intrahepatic blood vessels on the gross and histological characteristics of lesions produced by radiofrequency ablation in a pig liver model.

    PubMed

    Tamaki, Katsuyoshi; Shimizu, Ichiro; Oshio, Atsuo; Fukuno, Hiroshi; Inoue, Hiroshi; Tsutsui, Akemi; Shibata, Hiroshi; Sano, Nobuya; Ito, Susumu

    2004-12-01

    To determine whether the presence of large intrahepatic blood vessels (>/=3 mm) affect radiofrequency (RF)-induced coagulation necrosis, the gross and histological characteristics of RF-ablated areas proximal to or around vessels were examined in normal pig livers. An RF ablation treatment using a two-stepwise extension technique produced 12 lesions: six contained vessels (Group A), and the other six were localized around vessels (Group B). Gross examination revealed that the longest and shortest diameters of the ablated lesions were significantly larger in Group B than in Group A. In Group A, patent vessels contiguous to the lesion were present in a tongue-shaped area, whereas the lesions in Group B were spherical. Staining with nicotinamide adenine dinucleotide diaphorase was negative within the ablated area; but, if vessels were present in the ablated area, the cells around the vessels in an opposite direction to the ablation were stained blue. Roll-off can be achieved with 100% cellular destruction within a lesion that does not contain large vessels. The ablated area was decreased in lesions that contained large vessels, suggesting that the presence of large vessels in the ablated area further increases the cooling effect and may require repeated RF ablation treatment to achieve complete coagulation necrosis.

  1. Meta-analysis of bipolar radiofrequency endometrial ablation versus thermal balloon endometrial ablation for the treatment of heavy menstrual bleeding.

    PubMed

    Zhai, Yan; Zhang, Zihan; Wang, Wei; Zheng, Tingping; Zhang, Huili

    2018-01-01

    Heavy menstrual bleeding is a common problem that can severely affect quality of life. To compare bipolar radiofrequency endometrial ablation and thermal balloon ablation for heavy menstrual bleeding in terms of efficacy and health-related quality of life (HRQoL). Online registries were systematically searched using relevant terms without language restriction from inception to November 24, 2016. Randomized control trials or cohort studies of women with heavy menstrual bleeding comparing the efficacy of two treatments were eligible. Data were extracted. Results were expressed as risk ratios (RRs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs). Six studies involving 901 patients were included. Amenorrhea rate at 12 months was significantly higher after bipolar radiofrequency endometrial ablation than after thermal balloon ablation (RR 2.73, 95% CI 2.00-3.73). However, no difference at 12 months was noted for dysmenorrhea (RR 1.04, 95% CI 0.68-1.58) or treatment failure (RR 0.78, 95% CI 0.38-1.60). The only significant difference for HRQoL outcomes was for change in SAQ pleasure score (12 months: WMD -3.51, 95% CI -5.42 to -1.60). Bipolar radiofrequency endometrial ablation and thermal balloon ablation reduce menstrual loss and improve quality of life. However, bipolar radiofrequency endometrial ablation is more effective in terms of amenorrhea rate and SAQ pleasure. © 2017 International Federation of Gynecology and Obstetrics.

  2. From Laser Desorption to Laser Ablation of Biopolymers

    NASA Astrophysics Data System (ADS)

    Franz, Hillenkamp

    1998-03-01

    For selected indications laser ablation and cutting of biological tissues is clinical practice. Preferentially lasers with emission wavelengths in the far UV and the mid IR are used, for which tissue absorption is very high. Morphologically the ablation sites look surprisingly similar for the two wavelength ranges, despite of the very different prim y putative interaction mechanisms. Ablation depth as a function of fluence follows a sigmoidal curve. Even factors below the nominal ablation threshold superficial layers of material get removed from the surface. This is the fluence range for Matrix-Assisted Laser Desorption/Ionization (MALDI). Evidence will be presented which suggest that strong similarities exist between the desorption and ablation processes both for UV- as well as for IR-wavelengths.

  3. Testing of Advanced Conformal Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew; Agrawal, Parul; Beck, Robin

    2013-01-01

    In support of the CA250 project, this paper details the results of a test campaign that was conducted at the Ames Arcjet Facility, wherein several novel low density thermal protection (TPS) materials were evaluated in an entry like environment. The motivation for these tests was to investigate whether novel conformal ablative TPS materials can perform under high heat flux and shear environment as a viable alternative to rigid ablators like PICA or Avcoat for missions like MSL and beyond. A conformable TPS over a rigid aeroshell has the potential to solve a number of challenges faced by traditional rigid TPS materials (such as tiled Phenolic Impregnated Carbon Ablator (PICA) system on MSL, and honeycomb-based Avcoat on the Orion Multi Purpose Crew Vehicle (MPCV)). The compliant (high strain to failure) nature of the conformable ablative materials will allow better integration of the TPS with the underlying aeroshell structure and enable monolithic-like configuration and larger segments to be used in fabrication.A novel SPRITE1 architecture, developed by the researchers at NASA Ames was used for arcjet testing. This small probe like configuration with 450 spherecone, enabled us to test the materials in a combination of high heat flux, pressure and shear environment. The heat flux near the nose were in the range of 500-1000 W/sq cm whereas in the flank section of the test article the magnitudes were about 50 of the nose, 250-500W/sq cm range. There were two candidate conformable materials under consideration for this test series. Both test materials are low density (0.28 g/cu cm) similar to Phenolic Impregnated Carbon Ablator (PICA) or Silicone Impregnated Refractory Ceramic Ablator (SIRCA) and are comprised of: A flexible carbon substrate (Carbon felt) infiltrated with an ablative resin system: phenolic (Conformal-PICA) or silicone (Conformal-SICA). The test demonstrated a successful performance of both the conformable ablators for heat flux conditions between 50

  4. Microwave Tissue Ablation: Biophysics, Technology and Applications

    PubMed Central

    2010-01-01

    Microwave ablation is an emerging treatment option for many cancers, cardiac arrhythmias and other medical conditions. During treatment, microwaves are applied directly to tissues to produce rapid temperature elevations sufficient to produce immediate coagulative necrosis. The engineering design criteria for each application differ, with individual consideration for factors such as desired ablation zone size, treatment duration, and procedural invasiveness. Recent technological developments in applicator cooling, power control and system optimization for specific applications promise to increase the utilization of microwave ablation in the future. This article will review the basic biophysics of microwave tissue heating, provide an overview of the design and operation of current equipment, and outline areas for future research for microwave ablation. PMID:21175404

  5. Antibacterial effects of laser ablated Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Shamaila, S.; Wali, H.; Sharif, R.; Nazir, J.; Zafar, N.; Rafique, M. S.

    2013-10-01

    The interaction of nickel nanoparticles with Escherichia coli (E. coli) bacteria has been studied. The nickel nanoparticles have been fabricated by continuous wave laser ablation of nickel target and their properties are studied using different characterization techniques. The antibacterial activity of nickel nanoparticles was checked against E. coli bacteria. Escherichia coli were cultured in nutrients broth and different concentrations of nickel nanoparticles were added to bacterial culture solution to investigate the interaction of nickel nanoparticles with bacteria and to check toxicity of the nickel nanoparticles against E. coli. The fabricated Ni nanoparticles have exhibited considerable antimicrobial activity against E. coli.

  6. Early Efficacy Analysis of Biatrial Ablation versus Left and Simplified Right Atrial Ablation for Atrial Fibrillation Treatment in Patients with Rheumatic Heart Disease.

    PubMed

    Liu, Hong; Chen, Lin; Xiao, Yingbin; Ma, Ruiyan; Hao, Jia; Chen, Baicheng; Qin, Chuan; Cheng, Wei

    2015-08-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia. About 60% of patients with rheumatic heart disease have persistent AF. A total of 197 patients underwent valve replacement concomitant bipolar radiofrequency ablation (BRFA). Patients were divided into the biatrial ablation group and the simplified right atrial ablation group. In biatrial ablation group, the patients underwent a complete left and right atrial ablation. In simplified right atrial ablation group, the patients underwent a complete left atrial ablation and a simplified right atrial ablation. The conversion of sinus rhythm (SR) was high in both groups during the follow-up period. In the simplified right atrial ablation group, SR conversion rate was 88.29% at discharge. At six months and 12 months after surgery, 87.39% of patients and 86.49% of patients were in SR free of antiarrhythmic drugs, respectively. While in the biatrial ablation group, SA conversion rate was 89.53% at discharge. Percentage of patients in SR free of antiarrhythmic drugs was 88.37% and 88.37% at six months and 12 months after surgery, respectively. Echocardiography showed left atrial diameter decreased significantly after the surgery in the two groups. The ejection fraction and fractional shortening were improved significantly, without significant differences between the two groups. The results suggest that the concomitant left atrial and simplified right atrial BRFA for AF in patients undergoing valve replacement can achieve similar early efficiency as biatrial ablation. Copyright © 2015 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  7. Thermal distribution of microwave antenna for atrial fibrillation catheter ablation.

    PubMed

    Zhang, Huijuan; Nan, Qun; Liu, Youjun

    2013-09-01

    The aim of this study is to investigate the effects of ablation parameters on thermal distribution during microwave atrial fibrillation catheter ablation, such as ablation time, ablation power, blood condition and antenna placement, and give proper ablative parameters to realise transmural ablation. In this paper, simplified 3D antenna-myocardium-blood finite element method models were built to simulate the endocardial ablation operation. Thermal distribution was obtained based on the coupled electromagnetic-thermal analysis. Under different antenna placement conditions and different microwave power inputs within 60 s, the lesion dimensions (maximum depth, maximum width) of the ablation zones were analysed. The ablation width and depth increased with the ablation time. The increase rate significantly slowed down after 10 s. The maximum temperature was located in 1 mm under the antenna tip when perpendicular to the endocardium, while 1.5 mm away from the antenna axis and 26 mm along the antenna (with antenna length about 30 mm) in the myocardium when parallel to the endocardium. The maximum temperature in the ablated area decreased and the effective ablation area (with the temperature raised to 50°C) shifted deeper into the myocardium due to the blood cooling. The research validated that the microwave antenna can provide continuous long and linear lesions for the treatment of atrial fibrillation. The dimensions of the created lesion widths were all larger than those of the depths. It is easy for the microwave antenna to produce transmural lesions for an atrial wall thickness of 2-6 mm by adjusting the applied power and ablation time.

  8. Magnetic electroanatomical mapping for ablation of focal atrial tachycardias.

    PubMed

    Marchlinski, F; Callans, D; Gottlieb, C; Rodriguez, E; Coyne, R; Kleinman, D

    1998-08-01

    Uniform success for ablation of focal atrial tachycardias has been difficult to achieve using standard catheter mapping and ablation techniques. In addition, our understanding of the complex relationship between atrial anatomy, electrophysiology, and surface ECG P wave morphology remains primitive. The magnetic electroanatomical mapping and display system (CARTO) offers an on-line display of electrical activation and/or signal amplitude related to the anatomical location of the recorded sites in the mapped chamber. A window of electrical interest is established based on signals timed from an electrical reference that usually represents a fixed electrogram recording from the coronary sinus or the atrial appendage. This window of electrical interest is established to include atrial activation prior to the onset of the P wave activity associated with the site of origin of a focal atrial tachycardia. Anatomical and electrical landmarks are defined with limited fluoroscopic imaging support and more detailed global chamber and more focal atrial mapping can be performed with minimal fluoroscopic guidance. A three-dimensional color map representing atrial activation or voltage amplitude at the magnetically defined anatomical sites is displayed with on-line data acquisition. This display can be manipulated to facilitate viewing from any angle. Altering the zoom control, triangle fill threshold, clipping plane, or color range can all enhance the display of a more focal area of interest. We documented the feasibility of using this single mapping catheter technique for localizing and ablating focal atrial tachycardias. In a consecutive series of 8 patients with 9 focal atrial tachycardias, the use of the single catheter CARTO mapping system was associated with ablation success in all but one patient who had a left atrial tachycardia localized to the medial aspect of the orifice of the left atrial appendage. Only low power energy delivery was used in this patient because of the

  9. Dual beam optical system for pulsed laser ablation film deposition

    DOEpatents

    Mashburn, Douglas N.

    1996-01-01

    A laser ablation apparatus having a laser source outputting a laser ablation beam includes an ablation chamber having a sidewall, a beam divider for dividing the laser ablation beam into two substantially equal halves, and a pair of mirrors for converging the two halves on a surface of the target from complementary angles relative to the target surface normal, thereby generating a plume of ablated material emanating from the target.

  10. Electrolytic ablation of the rat pancreas: a feasibility trial

    PubMed Central

    Fosh, Beverley G; Finch, Jonathon Guy; Anthony, Adrian A; Texler, Michael; Maddern, Guy J

    2001-01-01

    Background Pancreatic cancer is a biologically aggressive disease with less than 20% of patients suitable for a "curative" surgical resection. This, combined with the poor 5-year survival indicates that effective palliative methods for symptom relief are required. Currently there are no ablative techniques to treat pancreatic cancer in clinical use. Tissue electrolysis is the delivery of a direct current between an anode and cathode to induce localised necrosis. Electrolysis has been shown to be safe and reliable in producing hepatic tissue and tumour ablation in animal models and in a limited number of patients. This study investigates the feasibility of using electrolysis to produce localised pancreatic necrosis in a healthy rat model. Method Ten rats were studied in total. Eight rats were treated with variable "doses" of coulombs, and the systemic and local effects were assessed; 2 rats were used as controls. Results Seven rats tolerated the procedure well without morbidity or mortality, and one died immediately post procedure. One control rat died on induction of anaesthesia. Serum amylase and glucose were not significantly affected. Conclusion Electrolysis in the rat pancreas produced localised necrosis and appears both safe, and reproducible. This novel technique could offer significant advantages for patients with unresectable pancreatic tumours. The next stage of the study is to assess pancreatic electrolysis in a pig model, prior to human pilot studies. PMID:11570977

  11. Global microwave endometrial ablation for menorrhagia treatment

    NASA Astrophysics Data System (ADS)

    Fallahi, Hojjatollah; Å ebek, Jan; Frattura, Eric; Schenck, Jessica; Prakash, Punit

    2017-02-01

    Thermal ablation is a dominant therapeutic option for minimally invasive treatment of menorrhagia. Compared to other energy modalities for ablation, microwaves offer the advantages of conformal energy delivery to tissue within short times. The objective of endometrial ablation is to destroy the endometrial lining of the uterine cavity, with the clinical goal of achieving reduction in bleeding. Previous efforts have demonstrated clinical use of microwaves for endometrial ablation. A considerable shortcoming of most systems is that they achieve ablation of the target by translating the applicator in a point-to-point fashion. Consequently, treatment outcome may be highly dependent on physician skill. Global endometrial ablation (GEA) not only eliminates this operator dependence and simplifies the procedure but also facilitates shorter and more reliable treatments. The objective of our study was to investigate antenna structures and microwave energy delivery parameters to achieve GEA. Another objective was to investigate a method for automatic and reliable determination of treatment end-point. A 3D-coupled FEM electromagnetic and heat transfer model with temperature and frequency dependent material properties was implemented to characterize microwave GEA. The unique triangular geometry of the uterus where lateral narrow walls extend from the cervix to the fundus forming a wide base and access afforded through an endocervical approach limit the overall diameter of the final device. We investigated microwave antenna designs in a deployed state inside the uterus. The impact of ablation duration on treatment outcome was investigated. Prototype applicators were fabricated and experimentally evaluated in ex vivo tissue to verify the simulation results and demonstrate proof-of-concept.

  12. Plume collimation for laser ablation electrospray ionization mass spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vertes, Akos; Stolee, Jessica A.

    2016-06-07

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  13. Plume collimation for laser ablation electrospray ionization mass spectrometry

    DOEpatents

    Vertes, Akos; Stolee, Jessica A.

    2014-09-09

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  14. Characterization of Air Plane Soot Surrogates using Raman spectroscopy and laser ablation techniques

    NASA Astrophysics Data System (ADS)

    Chazallon, Bertrand; Ortega, Ismael Kenneth; Ikhenazene, Raouf; Pirim, Claire; Carpentier, Yvain; Irimiea, Cornelia; Focsa, Cristian; Ouf, François-Xavier

    2016-04-01

    Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion [1]. Aircraft exhaust plumes contain species (gases and soot particles) produced by the combustion of kerosene with ambient air in the combustion chamber of the engine. Soot particles emitted by air-planes produce persistent contrails in the upper troposphere in ice-supersaturated air masses that contribute to cloudiness and impact the radiative properties of the atmosphere. These aerosol-cloud interactions represent one of the largest sources of uncertainty in global climate models [2]. Though the formation of atmospheric ice particles has been studied for many years [3], there are still numerous opened questions on nucleation properties of soot particles [4], as the ice nucleation experiments showed a large spread in results depending on the nucleation mode chosen and origin of the soot produced. The reasons behind these discrepancies reside in the different physico-chemical properties (composition, structure) of soot particles produced in different conditions, e.g., with respect to fuel or combustion techniques. In this work, we use Raman microscopy (514 and 785 nm excitation wavelengths) and ablation techniques (Secondary Ions Mass Spectrometry, and Laser Desorption Mass Spectrometry) to characterize soot particle surrogates produced from a CAST generator (propane fuel, four different global equivalence ratios). They are produced as analogues of air-plane soot collected at different engine regimes (PowerJet SaM-146 turbofan) simulating a landing and take-off (LTO) cycle (MERMOSE project (http://mermose.onera.fr/)) [6]. The spectral parameters of the first-order Raman bands of these soot samples are analyzed using a de-convolution approach described by Sadezky et al. (2005) [5]. A systematic Raman analysis is carried out to select a number of parameters (laser wavelength, irradiance at sample, exposure time) that will alter the sample and the

  15. Simulation of radiofrequency ablation in real human anatomy.

    PubMed

    Zorbas, George; Samaras, Theodoros

    2014-12-01

    The objective of the current work was to simulate radiofrequency ablation treatment in computational models with realistic human anatomy, in order to investigate the effect of realistic geometry in the treatment outcome. The body sites considered in the study were liver, lung and kidney. One numerical model for each body site was obtained from Duke, member of the IT'IS Virtual Family. A spherical tumour was embedded in each model and a single electrode was inserted into the tumour. The same excitation voltage was used in all cases to underline the differences in the resulting temperature rise, due to different anatomy at each body site investigated. The same numerical calculations were performed for a two-compartment model of the tissue geometry, as well as with the use of an analytical approximation for a single tissue compartment. Radiofrequency ablation (RFA) therapy appears efficient for tumours in liver and lung, but less efficient in kidney. Moreover, the time evolution of temperature for a realistic geometry differs from that for a two-compartment model, but even more for an infinite homogenous tissue model. However, it appears that the most critical parameters of computational models for RFA treatment planning are tissue properties rather than tissue geometry. Computational simulations of realistic anatomy models show that the conventional technique of a single electrode inside the tumour volume requires a careful choice of both the excitation voltage and treatment time in order to achieve effective treatment, since the ablation zone differs considerably for various body sites.

  16. Ultrasound-directed robotic system for thermal ablation of liver tumors: a preliminary report

    NASA Astrophysics Data System (ADS)

    Zheng, Jian; Tian, Jie; Dai, Yakang; Zhang, Xing; Dong, Di; Xu, Min

    2010-03-01

    Thermal ablation has been proved safe and effective as the treatment for liver tumors that are not suitable for resection. Currently, manually performed thermal ablation is greatly dependent on the surgeon's acupuncture manipulation against hand tremor. Besides that, inaccurate or inappropriate placement of the applicator will also directly decrease the final treatment effect. In order to reduce the influence of hand tremor, and provide an accurate and appropriate guidance for a better treatment, we develop an ultrasound-directed robotic system for thermal ablation of liver tumors. In this paper, we will give a brief preliminary report of our system. Especially, three innovative techniques are proposed to solve the critical problems in our system: accurate ultrasound calibration when met with artifacts, realtime reconstruction with visualization using Graphic Processing Unit (GPU) acceleration and 2D-3D ultrasound image registration. To reduce the error of point extraction with artifacts, we propose a novel point extraction method by minimizing an error function which is defined based on the geometric property of our N-fiducial phantom. Then realtime reconstruction with visualization using GPU acceleration is provided for fast 3D ultrasound volume acquisition with dynamic display of reconstruction progress. After that, coarse 2D-3D ultrasound image registration is performed based on landmark points correspondences, followed by accurate 2D-3D ultrasound image registration based on Euclidean distance transform (EDT). The effectiveness of our proposed techniques is demonstrated in phantom experiments.

  17. Rationale and design of the NO-PARTY trial: near-zero fluoroscopic exposure during catheter ablation of supraventricular arrhythmias in young patients.

    PubMed

    Casella, Michela; Dello Russo, Antonio; Pelargonio, Gemma; Bongiorni, Maria Grazia; Del Greco, Maurizio; Piacenti, Marcello; Andreassi, Maria Grazia; Santangeli, Pasquale; Bartoletti, Stefano; Moltrasio, Massimo; Fassini, Gaetano; Marini, Massimiliano; Di Cori, Andrea; Di Biase, Luigi; Fiorentini, Cesare; Zecchi, Paolo; Natale, Andrea; Picano, Eugenio; Tondo, Claudio

    2012-10-01

    Radiofrequency catheter ablation is the mainstay of therapy for supraventricular tachyarrhythmias. Conventional radiofrequency catheter ablation requires the use of fluoroscopy, thus exposing patients to ionising radiation. The feasibility and safety of non-fluoroscopic radiofrequency catheter ablation has been recently reported in a wide range of supraventricular tachyarrhythmias using the EnSite NavX™ mapping system. The NO-PARTY is a multi-centre, randomised controlled trial designed to test the hypothesis that catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX™ mapping system results in a clinically significant reduction in exposure to ionising radiation compared with conventional catheter ablation. The study will randomise 210 patients undergoing catheter ablation of supraventricular tachyarrhythmias to either a conventional ablation technique or one guided by the EnSite NavX™ mapping system. The primary end-point is the reduction of the radiation dose to the patient. Secondary end-points include procedural success, reduction of the radiation dose to the operator, and a cost-effectiveness analysis. In a subgroup of patients, we will also evaluate the radiobiological effectiveness of dose reduction by assessing acute chromosomal DNA damage in peripheral blood lymphocytes. NO-PARTY will determine whether radiofrequency catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX™ mapping system is a suitable and cost-effective approach to achieve a clinically significant reduction in ionising radiation exposure for both patient and operator.

  18. Towards multispectral endoscopic imaging of cardiac lesion assessment and classification for cardiac ablation therapy

    NASA Astrophysics Data System (ADS)

    Park, Soo Young; Singh-Moon, Rajinder P.; Hendon, Christine P.

    2018-02-01

    Pulmonary vein (PV) isolation is a critical procedure for the treatment and termination of atrial fibrillation (AF). The success of such treatment depends on the extent of tissue damage, where partial lesions can allow abnormal electrical conduction and risk relapse of AF. Proper evaluation of lesion delivery and ablation line continuity remains challenging with current techniques and in part limit procedural efficacy. A tool for direct visualization of endo-myocardial lesions in vivo could potentially reduce ambiguity in treatment location and extent and improve the overall fidelity of lesion sets. In this work, we introduce a method for wide-field visualization of myocardial tissue including the discernment of ablated and non-ablated regions using an endoscopic multispectral imaging system (EMIS). The system was designed to fit the working channel of most commercial sheathes (<4 Fr) and supported quadruple-wavelength reflectance imaging through a flexible fiber-bundle. A total of 50 endocardial lesions were created and imaged on nine swine hearts, ex vivo in addition to 15 lesions on human LA samples near PV regions. A pixel-wise linear discriminant analysis algorithm was developed to classify regions of ablation treatment based on calibrated EMI maps. Results show good agreement of treatment severity and spatial extent compared to post-hoc tissue vital staining.

  19. Results of endocardial radiofrequency ablation of atrial fibrillation during mitral valve surgery.

    PubMed

    Demirkilic, U; Bolcal, C; Gunay, C; Doganci, S; Temizkan, V; Kuralay, E; Tatar, H

    2006-08-01

    The aim of the study is to evaluate the efficacy of thermocontrolled endocardial radiofrequency (RF) ablation for the patients with mitral valve disorder and associated chronic atrial fibrillation during mitral valve replacement operation. Between February 2002 and January 2004, 43 patients with mitral valve disease and associated chronic atrial fibrillation underwent mitral valve replacement and thermocontrolled endocardial RF ablation with Cobra RF system flexible probe at Gulhane Military Academy of Medicine, Department of Cardiovascular Surgery. Eighteen of the patients (41.8%) were males, while the remaining 25 (58.2%) were females. The average age of the patients was 44+/-14.21 (18-66) years. Functional capacity of the patients was class II in 15 (34. 9%), class III in 24 (55.8%), class IV in 4 (9.3%) according to the NYHA classification. At the preoperative period all of the patients were evaluated routinely by twelve-lead ECG, chest film and transthoracic echocardiography (TTE). For the patients over 40 years of age, we performed additional coronary angiography to delineate any coronary lesions. The patients were evaluated at months 1, 3, 6 and annually by twelve-lead ECG, TTE and holter monitoring after discharge. There were not any complications related to the performed technique. No operative and hospital mortality were recorded. At the follow-up period for 35 of 43 patients (81.4%) sinus rhythm was restored. The mean follow-up time was 24.3+/-11.2 (12-35) months. Endocardial RF ablation especially during mitral valve surgery is a simple technique to be performed. Early and midterm results of the cohort are satisfying.

  20. Prospects for Practical Laser Ablation U/Pb and (U-Th)/He Double-Dating (LADD) of Detrital Apatite

    NASA Astrophysics Data System (ADS)

    Horne, A.; Hodges, K. V.; Van Soest, M. C.

    2017-12-01

    A laser ablation micro-analytical technique for (U-Th)/He dating has been shown to be an effective approach to the thermochronologic study of detrital zircons (Tripathy-Lang et al., J. Geophys. Res., 2013), while Evans et al. (J. Anal. At. Spectrom., 2015) and Horne et al. (Geochim. Cosmochim. Acta, 2016) demonstrated how the technique could be modified to enable laser ablation U/Pb and (U-Th)/He double-dating (LADD) of detrital zircon and titanite. These successes beg the question of whether or not LADD is viable for another commonly encountered detrital mineral: apatite. Exploratory LADD studies in Arizona State University's Group 18 Laboratories - using Durango fluorapatite, apatite from the Fish Canyon tuff, and detrital apatite from modern fluvial sediments in the eastern Sierra Nevada of California - illustrate that the method is indeed viable for detrital apatite. However, the method may not be appropriate for all detrital samples. For example, many apatite grains encountered in detrital samples from young orogenic settings have low concentrations of U and Th and small crystal sizes. This can lead to imprecise laser ablation (U-Th)/He dates, especially for very young grains potentially obscuring or inhibiting relevant interpretations of the data set.