Development of non-invasive flexible directional microwave ablation for central lung cancer: a simulation study.

Transbronchial microwave ablation (MWA) with flexible antennas has gradually become an attractive alternative to percutaneous MWA for lung cancer due to its characteristic of non-invasiveness. However, flexible antennas for the precision ablation of lung tumors that are adjacent to critical bronchial structures are still not available. In this study, a non-invasive flexible directional (FD) antenna for early stage central lung tumors surrounding the bronchia was proposed. A comprehensive numerical MWA model with the FD antenna was developed in a real human-sized left lung model. The structure of the antenna and the treatment protocol were optimized by a generic algorithm for the precision ablation of two cases of early stage central lung cancer (i.e. spherical-like and ellipsoidal tumors). The electromagnetic efficiency of the optimized antenna was also improved by implementing an optimizedπ-matching network for impedance matching. The results indicate that the electromagnetic energy of MWA can be restricted to a particular area for precision ablation of specific lung tumors using the FD antenna. This study contributes to the field of lung cancer management with MWA.

Numerical study of the induction of intratumoral apoptosis under microwave ablation by changing slot length of microwave coaxial antenna.

Recent advances in technology have led to an increase in the detection of previously undetected deep-located tumor tissue. As a result, the medical field is using a variety of methods to treat deep-located tumors, and minimally invasive treatment techniques are being explored. In this study, therapeutic effect of microwave ablation (MWA) on tumor generated inside liver tissue was analyzed through numerical analysis. The distribution of electromagnetic fields in biological tissues emitted by microwave coaxial antenna (MCA) was calculated through the wave equation, and the thermal behavior of the tissue was analyzed through the Pennes bioheat equation. Among various treatment conditions constituting MWA, tumor radius and the slot length inside the MCA were changed, and the resulting treatment effect was quantitatively confirmed through three apoptotic variables. As a result, each tumor radius has optimal power condition for MWA, 2.6W, 2.4W, and 3.0W respectively. This study confirmed optimal therapeutic conditions for MWA. Three apoptotic variables were used to quantitatively identify apoptotic temperature maintenance inside tumor tissue and thermal damage to surrounding normal tissue. The findings of this study are expected to serve as a standard for treatment based on actual MWA treatment.

The influence of microwave ablation parameters on the positioning of trocar in different cancerous tissues: a numerical study.

The present study analyzed the microwave ablation of cancerous tumors located in six major cancer-prone organs and estimated the significance of input power and treatment time parameters in the apt positioning of the trocar into the tissue during microwave ablation. The present study has considered a three-dimensional two-compartment tumour-embedded tissue model. FEA based COMSOL Multiphysics software with inbuilt bioheat transfer, electromagnetic waves, heat transfer in solids and fluids, and laminar flow physics has been used to obtain the numerical results. Based on the mortality rates caused by cancer, the present study has considered six major organs affected by cancer, viz. lung, breast, stomach/gastric, liver, liver (with colon metastasis), and kidney for MWA analysis. The input power (100 W) and ablation times (4 minutes) with apt and inapt positioning of the trocar have been considered to compare the ablation volume of various cancerous tissues. The present study addresses one of the major problems clinicians face, i.e. the proper placement of the trocar due to poor imaging techniques and human error, resulting in incomplete tumor ablation and increased surgical procedures. The highest values of the ablation region have been observed for the liver, colon metastatic liver and breast cancerous tissues compared with other organs at the same operating conditions.

The present study has investigated the application of microwave ablation for cancer treatment in six major organs, specifically emphasizing the evaluation of ablation volume during the procedure. Using COMSOL-Multiphysics software, the study has investigated MWA of tumor embedded organs in the lung, breast, stomach, liver, and kidney. The positioning of the trocar, a crucial element in the treatment process, has been examined to address challenges in effectively ablating tumors.From the results, it has been revealed that liver, colon metastatic liver, and breast cancer tissues exhibited the largest areas of ablation volume compared with other organs.Organs like the breast and hepatic glands, characterized by lower heat capacity and density, have shown larger ablation zones. Trocar positioning significantly influenced the stomach, liver, and kidney, where improper placement led to notable increases in ablation volume, posing a risk of unintended damage to healthy tissue.Further, the study has concluded that precise trocar positioning plays a crucial role in optimizing microwave ablation. This precision has the potential to enhance the effectiveness of cancer treatments while minimizing harm to healthy tissue. The insights gained from this research offer valuable information for clinicians looking to enhance the precision of cancer therapies, ultimately aiming for improved outcomes for patients.

A comparison of three different microwave systems for laparoscopic liver tumor ablation.

BACKGROUND: Our aim was to perform a comparison of three current microwave ablation (MWA) systems widely used for laparoscopic liver ablations in terms of ablation kinetics and geometry of ablation zones. METHODS: This was a retrospective, institutional review board-approved study comparing Emprint, Emprint HP, and NeuWave systems for laparoscopic liver ablation. Analyses were performed via Mann-Whitney U and χ2 tests. Continuous data are presented as median (interquartile range). RESULTS: For Emprint, Emprint HP, and NeuWave groups, tumor size was 1.16 (0.8), 1.21 (0.7), and 1.27 (0.9) cm (p = 0.54). Ablation time per lesion was 7 (6), 4 (2.8), and 4 (3.3) min (p < 0.0001), yielding similar ablation zone volumes and margins. The time to first ablation bubble was 1 (0.13), 1.5 (0.85), and 0.75 (0.5) min, and total ablation times were 7 (4.4), 4 (2), and 3.5 (2.8) min (p < 0.0001). The roundness index A, B, and transverse were 0.94, 0.98, and 0.79; 0.95, 0.95, and 0.78; and 1.02, 0.95, and 0.96. CONCLUSIONS: Although a saline-cooling system with Emprint system allowed for larger diameter spherical ablation zones to be created, it led to decreased efficiency compared to the CO2-cooled NeuWave system, which exposes the active antenna directly to tissue. Increased power delivered by Emprint HP improved the efficiency of saline-cooled design, as demonstrated by faster ablation times.

A systematic review and meta-analysis of mechanochemical endovenous ablation using Flebogrif for varicose veins.

OBJECTIVE: In the present study, we reviewed and analyzed the currently available data on the Flebogrif device (Balton, Warsaw, Poland) to define its role in the global varicose vein treatment devices market. METHODS: A systematic literature search was performed in MEDLINE, Embase, and the Cochrane Library. Studies were eligible if they had included patients treated using the Flebogrif for saphenous vein incompetence, had been reported in English, and had the full text available. The methodologic quality of the studies was assessed using the methodologic index for nonrandomized studies (MINORS) score. A random effects model was used to estimate the primary outcome of anatomic success, defined as the occlusion rate of the treated vein. The estimates are reported with the 95% confidence intervals (CIs). The secondary outcomes were clinical success, complication rate, pain during and after the procedure, and time to return to work. RESULTS: Five articles met the inclusion criteria, reporting 348 procedures in 392 patients. Four studies reported the 3-month anatomic success, and three studies reported the 12-month anatomic success. The pooled 3-month anatomic success rate was 95.6% (95% CI, 93.2%-98.0%). The 12-month anatomic success rate was 93.2% (95% CI, 90.3%-96.1%). The only major complication reported within 3 months was deep vein thrombosis, which developed in 0.3% of the patients. The minor complications of thrombophlebitis and hyperpigmentation had occurred in 13.3% to 14.5% and 3.3% to 10.0% of patients, respectively, within 3 months. The methodologic quality of the included studies was moderate. CONCLUSIONS: Mechanochemical ablation using the Flebogrif device is a safe and well-tolerated procedure for the treatment of saphenous vein insufficiency. However, well-designed studies of sufficient sample size and follow-up are required to compare the effectiveness with other endovenous treatment modalities and define the definitive role of the Flebogrif device.

Novel platinum bipolar electrode for irreversible electroporation in prostate cancer: preclinical study in the beagle prostate.

The exposure of the prostate to high electric field strength during irreversible electroporation (IRE) has been extensively investigated. Multiple monopolar electrodes, however, have risks of organ piercing and bleeding when placing electrodes. A novel bipolar electrode made of pure platinum and stainless steel was developed for prostate cancer ablation. Voltages of 500 and 700 V were applied to the beagle prostate with this electrode to evaluate ablated tissues and their characteristics. IRE procedures were technically successful in all dogs without procedure-related complications. The current that flowed through the anode and cathode while applying 500 and 700 V were 1.75 ± 0.25 A and 2.22 ± 0.35 A, respectively. TUNEL assays showed that the estimated ablated areas when applying 500 and 700 V were 0.78 cm2 and 1.21 cm2, respectively. The minimum electric field strength threshold required for induction of IRE was 800 V/cm. The platinum electrode was resistant to corrosion. The IRE procedure for beagle prostates using a single bipolar electrode was technically feasible and safe. The novel bipolar electrode has great potential for treating human prostate cancer with fewer IRE-related complications.

Clinical Performance of a Powered Surgical Stapler for Left Atrial Appendage Resection in a Video-Assisted Thoracoscopic Ablation for Patients with Nonvalvular Atrial Fibrillation.

Left atrial appendage (LAA) has been found to be associated with the occurrence of thromboembolism in patients with nonvalvular atrial fibrillation (NVAF). Stapling exclusion of LAA during surgical ablation could be an alternative to oral anticoagulation for NVAF patients. However, its safety and efficacy have rarely been examined. Thus, in this study, we aimed to evaluate the safety and efficacy of a powered surgical stapler for LAA resection during ablation for patients with NVAF.Adult patients with NVAF undergoing stapler surgery were included in this study. LAAs of patients were cut off using a powered surgical stapler. Intraoperative transesophageal echocardiogram (TEE) was applied before and after the operation. Each patient received anticoagulant therapy for 2 months after surgery and was regularly followed up by appointment or via telephone call. Patients would undergo physical examinations, echocardiography, and 24-hour dynamic electrocardiogram in a local or in our hospital to determine whether there was a recurrence of atrial fibrillation (AF) or thromboembolism caused by AF.In total, 124 patients were included in this study (male: 88 (71.0%); mean age: 62.3 years). Blood loss was less than 100 mL in all patients with no operative complications or hospital deaths. Moreover, 119 (96.0%) follow-up data were collected, with a mean period of 27.4 months. All patients discontinued oral anticoagulants 2 months after their operation. As per our findings, AF recurred in 23 patients (18.5%), with an average of 9.1 months after surgery. No patients were diagnosed with thromboembolism related to AF.Stapling exclusion of LAA during surgical ablation could safely and completely resect the LAA. The effect of thrombus prevention was deemed satisfactory.

Mechanical and Ablative Minimally Invasive Techniques for Male LUTS due to Benign Prostatic Obstruction: A Systematic Review according to BPH-6 Evaluation.

The treatment of male lower urinary tract symptoms (LUTS) due to benign prostatic obstruction represents one of the major interesting aspects in urological clinical practice. Although transurethral resection of the prostate is still considered the surgical gold standard for treatment of benign prostatic hyperplasia with prostate volume <80 mL, various minimally invasive surgical treatments (MITs) have been developed to overcome the limitations of the "conventional" surgery. To date, there are no validated tools to evaluate the surgical outcomes of MITs; however, in the past, BPH-6 has been used for this purpose. In this systematic review, we evaluated the efficacy and safety of MITs according to BPH-6 score system. We focused our attention on MITs based on mechanical devices (prostatic urethral lift and the temporary implantable nitinol device) and techniques for prostate ablation (image guided robotic waterjet ablation and convective water vapor energy ablation). Evidence shows that MITs are capable of leading to an improvement in LUTS without having an overwhelming impact on complications and are a valid alternative to other treatments in patients who wish to preserve their sexual function or in case of inapplicability of conventional surgery. However, comparative studies between these techniques are still missing.

Relationship of Antenna Work and Ablation Cavity Volume Following Percutaneous Microwave Ablation of Hepatic Tumors.

PURPOSE: To formulate a statistical model relating ablation time, power, and work with posttreatment cavity volume following percutaneous microwave ablation of hepatic tumors in vivo. MATERIALS AND METHODS: A retrospective review (October 2015 to October 2018) yielded 122 hepatic tumors treated with microwave ablation. Ablation cavity dimensions were measured at 1-month follow-up examination and calculated using an ellipsoid volume formula. The antenna manufacturer (Neuwave Medical, Madison, Wisconsin) provided the activation time and energy used to calculate the antenna work. Generalized estimating equations with ordinary least-squares regression models were obtained to relate tumor volume with cumulative antenna work. Coefficient of determination (R2) and mean square error were used as statistical measures of model prediction performance. RESULTS: There is a logarithmic relationship between postablation cavity volume (cm3) and cumulative work (kJ), represented by the formula: log10 cm3 = -0.4583 + 0.9887 × cumulative work (log10 kJ) (R2 = 0.41, mean square error, 0.102). Ablation volumes were predicted as a function of antenna work, calculated using an antilog transformation. When a single antenna was used, ablation cavity volume was predicted using a generalized estimating equation ordinary least-squares regression model of power and time: log10cm3= -0.0546 + 0.0485 × total time (min) + 0.0107 × power (W) (R2 = 0.30; mean square error, 0.106). Using this model, a nomogram was developed to predict the postablation cavity volume based on total activation time and target power. CONCLUSION: There is a logarithmic relationship between the ablation work and posttreatment ablation cavity volume, which can be expressed in a nomogram when using a single probe.

TurboHawk plaque rotation system for treatment of arteriosclerosis occlusion in lower extremities: A pilot retrospective study.

ABSTRACT: This pilot study retrospectively assessed the feasible efficacy of TurboHawk plaque rotation system (THPRS) for treatment of arteriosclerosis occlusion in lower extremities (AOLE).A total of 36 eligible patients with AOLE were included in this pilot retrospective study. We divided all those patients into a treatment group and a control group, each group 18 patients. All patients in both groups administered conventional therapy. Additionally, all patients in the treatment group received THPRS, while all patients in the control group received percutaneous transluminal angioplasty (PTA) and percutaneous transluminal stenting (PTS). All outcomes were evaluated and analyzed at 3-month after surgery.At 3-month postsurgery, there were not significant statistical differences in clinical manifestations (intermittent claudication, P = .49; resting pain, P = .28), ankle brachial index change (P = .07), 6-minute walk distance (P = .43), and complications between 2 groups.This pilot study did not show better outcome improvement of THPRS for patients with AOLE. We cautiously draw the present conclusion, because it suffers from several major restrictions. Thus, further studies with larger sample size and longer term follow-up are still needed to warrant the current conclusion.

Initial single centre experience of Aquablation of the prostate using the AquaBeam system with athermal haemostasis for the treatment of benign prostatic hyperplasia: 1-year outcomes.

PURPOSE: Aquablation using the AquaBeam system combines real-time image guidance and robotics to enable precise and heat-free removal of prostatic tissue with a high velocity water jet. The aim of this study is to report the outcomes of Aquablation up to 1 year in a single centre within the UK employing an athermal approach to haemostasis. METHODS: Fifty-five consecutive men underwent Aquablation between September 2017 and December 2018 (as part of OPEN WATER trial). Standard Aquablation was performed with the AquaBeam system (PROCEPT® BioRobotics) with 2 passes of Aquablation followed by bladder washout with application of continuous bladder irrigation via a catheter on a continuous traction device. Patients were followed up at 3 and 12 months. The data were prospectively collected on patient demographics, uroflowmetry, prostate volume, International Prostate Symptom Score (IPSS), Male Sexual Health Questionnaire for Ejaculatory Dysfunction (MSHQ-EjD) and International Index of Erectile Function (IIEF-15). RESULTS: The mean age was 64.1 ± 7.9 years. Operating time was 26.9 ± 9.2 min. Mean prostate volume decreased from 58.2 ± 23.9 cc to 33.2 ± 12.9 cc (p < 0.0001). There were significant improvements at the 12 month follow-up in maximum urinary flow rate (9.9 ± 5.1 ml/s vs. 23.9 ± 11.6 ml/s), IPSS (21.7 ± 7.4 vs. 6.1 ± 4.2) and quality of life score (4.8 ± 1.1 vs. 1.4 ± 1.4) (p < 0.0001). There was no significant change in IIEF-15 and MSHQ-EjD scores. There were 8 (14.5%) Clavien grade 2 or higher complications. CONCLUSION: Our single centre experience suggests Aquablation using an entirely athermal approach is a safe cavitating procedure resulting in significant LUTS improvement comparable to standard cavitating procedures with greater preservation of sexual function.

Vaginal Rejuvenation: A Retrospective Review of Lasers and Radiofrequency Devices.

BACKGROUND: Vaginal rejuvenation is a topic of interest to multiple specialties, including dermatologists, plastic and reconstructive surgeons, urologists, and gynecologists. Evidence suggests that minimally invasive, energy-based devices-radiofrequency and laser therapy-are effective at vaginal tightening and decreasing symptoms of genitourinary syndrome of menopause (GSM) and/or vulvovaginal atrophy (VVA). MATERIALS AND METHODS: A systematic review was completed using PubMed in November 2018 with search terms "vaginal" or "vagina" and "rejuvenation" or "tightening" or "laxity" or "radiofrequency" or "laser," as well as "genitourinary syndrome of menopause," "pelvic prolapse," "atrophic vaginitis," "vulvovaginal atrophy," "sexual function," "urinary incontinence," and "radiofrequency" or "laser." Inclusion criteria were articles written in English and clinical trials or case reports/series dealing with human subjects. RESULTS: We identified 59 studies (3,609 women) treated for vaginal rejuvenation using either radiofrequency or fractional ablative laser therapy. Studies report improvement in symptoms of GSM/VVA and sexual function, high patient satisfaction, and minor adverse events, including treatment-associated pain, swelling, or vaginal discharge. CONCLUSION: This review demonstrates radiofrequency and laser are efficacious for the treatment of vaginal laxity and/or atrophy. Further research needs to be completed to determine which specific pathologies can be treated, if maintenance treatment is necessary, and long-term safety concerns.

Reasons to overthrow TURP: bring on Aquablation.

PURPOSE: In this review, we will discuss the state of the literature regarding Aquablation, its limitations, and opportunities for its application in the treatment of benign prostatic enlargement (BPE). METHODS: A comprehensive review of original research on Aquablation was conducted. Articles related to transurethral resection of the prostate, holmium laser enucleation of the prostate, greenlight photoselective vaporization of the prostate, and simple prostatectomy were reviewed for discussion. RESULTS: For small-medium prostates (30-80 mL), Aquablation's main advantages include better ejaculatory function and similar functional outcomes compared to TURP. For large prostates (80-150 mL), Aquablation demonstrates shorter operative time and superior ejaculatory function when compared to simple prostatectomy, HoLEP, and Greenlight PVP. In addition, Aquablation displays shorter hospital stays than simple prostatectomy. The integration of software programming and semi-automatic technology increases the reproducibility of the procedure and helps standardize overall outcomes, while also accelerating the learning curve. Its ability to preserve antegrade ejaculation makes Aquablation a very compelling option for sexually active patients. However cost and postoperative bleeding risks remain a concern. CONCLUSION: The current evidence suggests that Aquablation is a safe and effective alternative for BPE for small to large prostates. Further prospective clinical trials, with comparisons to other BPE modalities, and data from longer follow-up periods are still required.

Investigation of safety for electrochemotherapy and irreversible electroporation ablation therapies in patients with cardiac pacemakers.

BACKGROUND: The effectiveness of electrochemotherapy of tumors (ECT) and of irreversible electroporation ablation (IRE) depends on different mechanisms and delivery protocols. Both therapies exploit the phenomenon of electroporation of the cell membrane achieved by the exposure of the cells to a series of high-voltage electric pulses. Electroporation can be fine-tuned to be either reversible or irreversible, causing the cells to either survive the exposure (in ECT) or not (in IRE), respectively. For treatment of tissues located close to the heart (e.g., in the liver), the safety of electroporation-based therapies is ensured by synchronizing the electric pulses with the electrocardiogram. However, the use of ECT and IRE remains contraindicated for patients with implanted cardiac pacemakers if the treated tissues are located close to the heart or the pacemaker. In this study, two questions are addressed: can the electroporation pulses interfere with the pacemaker; and, can the metallic housing of the pacemaker modify the distribution of electric field in the tissue sufficiently to affect the effectiveness and safety of the therapy? RESULTS: The electroporation pulses induced significant changes in the pacemaker ventricular pacing pulse only for the electroporation pulses delivered during the pacing pulse itself. No residual effects were observed on the pacing pulses following the electroporation pulses for all tested experimental conditions. The results of numerical modeling indicate that the presence of metal-encased pacemaker in immediate vicinity of the treatment zone should not impair the intended effectiveness of ECT or IRE even when the casing is in direct contact with one of the active electrodes. Nevertheless, the contact between the casing and the active electrode should be avoided due to significant tissue heating at the site of the other active electrode for the IRE protocol and may cause the pulse generator to fail to deliver the pulses due to excessive current draw. CONCLUSIONS: The observed effects of electroporation pulses delivered in close vicinity of the pacemaker or its electrodes do not indicate adverse consequences for either the function of the pacemaker or the treatment outcome. These findings should contribute to making electroporation-based treatments accessible also to patients with implanted cardiac pacemakers.

A Digital Controlled Pulse Generator for a Possible Tumor Therapy Combining Irreversible Electroporation With Nanosecond Pulse Stimulation.

The irreversible electroporation with microsecond electric pulses is a new ablation technique adopted in the tumor therapy worldwide. On the other hand, the nsPEF (nanosecond pulsed electric field) has been proved to provide a means to induce immunogenic cell death and elicits antitumor immunity, which is under intensive in-vitro and in-vivo studies and in clinical trials. Normally, one needs two different types of electric pulse generators for producing the pulses in the ranges of nanosecond and microsecond, respectively. In order to realize these two types of tumor treatments in complementary and optimize electrical pulse parameters, we have developed a compact high-voltage pulse generator with a wide pulse width tuning range, based on a capacitor discharging configuration digitally controlled by a silicon carbide MOSFET switching array through a pair of optic-coupler drivers. The developed digital pulse generator is capable of adjusting: pulse width over 100-100 µs, voltage over 0-2 kV and repetition rate up to 1.2 kHz. The pulse generator is designed in simulation, implemented and verified in experiments. The pulse generator is shown to deliver a complementary treatment on Murine melanoma B16 cell lines, i.e., triggering the cell early apoptosis under the 300 ns pulse stimulation while a complete killing under the 100 ns pulses. The pulse generator is further demonstrated to induce antitumor immunity in a preliminary in vivo study on the mice model.

Performance of a New Blunt-Tip Needle for the Displacement of Critical Structure in Thermal Ablation.

PURPOSE: To ascertain the performance of a new blunt-tip needle (HydroGuard®), which allows injection of fluids during needle advancement in order to safely approach, displace and insulate nearby critical structures during thermal ablation (TA). MATERIALS AND METHODS: This study included 27 consecutive patients treated by TA [cryoablation (CA), radiofrequency (RFA), and microwave MWA)] between April 2018 and January 2019. During TA, hydro- or gas dissection was performed with HydroGuard® needle to displace and protect critical structures close to the tumor (< 10 mm). Technical and clinical success, distance between critical structure and tumor before and after hydro/gas dissection and complications were recorded. RESULTS: Eighteen patients were treated by CA (66.7%), 7 by MWA (25.9%) and 2 by RFA (7.4%). Majority of patients were treated with a curative intent (24/27; 88.8%). Adjacent critical structures include vessels (n = 3), nerves (n = 10), ureter/renal pelvis (n = 3), bowel/rectum (n = 10), stomach: (n = 3), diaphragm (n = 2), and pleura (n = 1). Technical success was 100%. Clinical success was 88% (24/27). Median minimum distance to adjacent critical structures before hydro/gas dissection was 1 mm (range 0-9 mm; IQR: 0-3 mm) versus 10.5 mm (range 4-47 mm; IQR: 9.7-18 mm) after displacement. Of the 27 patients treated, four developed complications (14.8%; 95% CI: 1.4-28.2): 1 major (3.7%; 95% CI: 0-10.8) and 3 minors (11.1%; 95% CI: 0-23). Only one minor complication was related to inadequate hydro-dissection, resulting in close proximity of the critical structure to the ablation zone. CONCLUSION: HydroGuard® is a safe and effective needle when used to approach, displace and insulate nearby critical structures during TA.

Laser Interstitial Thermal Therapy.

Laser interstitial thermal therapy (LITT) is a minimally invasive and cytoreductive neurosurgical technique that has gained significant momentum in the last decade. Several technological enhancements such as MRI thermometry and improved laser probe design have enabled feasibility and improved the safety of LITT procedures. Numerous reports have been published describing the treatment of lesions ranging from tumors to epileptogenic foci, but the indications for LITT continue to evolve. We describe the general physical and biological concepts underlying LITT, clinical workflow, and established and emerging indications.

An Italian experience with mechanochemical ablation of the saphenous vein since 2012.

OBJECTIVE: Mechanochemical endovenous ablation is a nonthermal method to ablate superficial incompetent veins. The aim of this paper was to assess short-term complications and 5-year follow-up outcomes. METHODS: This is a retrospective single-center study of data collected prospectively. We treated, in an outpatient setting, 395 primary, symptomatic, unilateral, incompetent varicose saphenous veins. No patients were treated bilaterally in the same session. The majority were great saphenous veins (92.3%), and the others were small saphenous veins. Procedures were performed with a mechanochemical endovenous occlusion catheter (ClariVein endovenous occlusion catheter; Merit Medical, South Jordan, Utah) and polidocanol 2% in liquid form. RESULTS: Follow-up was available for 329 patients treated between September 2012 and September 2017 with a mean follow-up time of 20 ± 18 months (range, 6-60 months). Technical success was achieved in 99.5%; in two patients, we were unable to complete the procedures because of vein spasm leading to catheter damage and inability to infuse the sclerosant. Follow-up was performed with clinical evaluation and duplex ultrasound scan at 1 week, 1 month, 6 months, and 1 year and then once every year. The overall survival rate free from recanalization was 92.4%. Anatomic success is 94% at 1 year, 91% at 2 years, 88% at 3 years, 88% at 4 years, and 84% at 5 years. The follow-up at 5 years includes 23 patients, 5 of whom presented with recanalization; moreover, in this series, in 36% of cases, the veins completely disappeared on duplex ultrasound scan. CONCLUSIONS: The ClariVein catheter is associated with a good occlusion rate, comparable with other techniques including thermal techniques, without major complications.

Directional Microwave Ablation: Experimental Evaluation of a 2.45-GHz Applicator in Ex Vivo and In Vivo Liver.

PURPOSE: To experimentally characterize a microwave (MW) ablation applicator designed to produce directional ablation zones. MATERIALS AND METHODS: Using a 14-gauge, 2.45-GHz side-firing MW ablation applicator, 36 ex vivo bovine liver ablations were performed. Ablations were performed at 60 W, 80 W, and 100 W for 3, 5, and 10 minutes (n = 4 per combination). Ablation zone forward and backward depth and width were measured and directivity was calculated as the ratio of forward to backward depth. Thirteen in vivo ablations were performed in 2 domestic swine with the applicator either inserted into the liver (80 W, 5 min, n = 3; 100 W, 5 min, n = 3; 100 W, 10 min, n = 2) or placed on the surface of the liver with a nontarget tissue placed on the back side of the applicator (80 W, 5 min, n = 5). The animals were immediately euthanized after the procedure; the livers were harvested and sectioned perpendicular to the axis of the applicator. In vivo ablation zones were measured following viability staining and assessed on histopathology. RESULTS: Mean ex vivo ablation forward depth was 8.3-15.5 mm. No backward heating was observed at 60 W, 3-5 minutes; directivity was 4.7-11.0 for the other power and time combinations. In vivo ablation forward depth was 10.3-11.5 mm, and directivity was 11.5-16.1. No visible or microscopic thermal damage to nontarget tissues in direct contact with the back side of the applicator was observed. CONCLUSIONS: The side-firing MW ablation applicator can create directional ablation zones in ex vivo and in vivo tissues.