Ablation Mode Research Articles

Ex-vivo experimental study of ultrasound-guided radiofrequency ablation for the treatment of hepatocellular carcinoma

Objective: To explore the effective mode of ultrasound-guided radiofrequency ablation for the treatment of hepatocellular carcinoma (HCC). Methods: The morphological changes of human liver cancer cells HepG2 and human permanent liver cells LO2 after high temperature treatment were observed. The cell counting kit 8 (CCK-8) array was used to detect cell proliferation ability. The HepG2 cells (ΔHepG2 cells) and LO2 cells (ΔLO2 cells) those were still alive after treatment with 47℃ were collected and subjected to secondary high temperature treatment, and their proliferation ability was tested by the CCK-8 array. The ablation was performed at different locations of the ex-vivo porcine liver. The consistency of the vaporization area of the ultrasound image with that of the actual ablation was compared, the temperature of each area in the ultrasonic image was observed. Results: After incubated water was heated to 50℃, with the extension of the culture time, the number of adherent cells of HepG2 and LO2 cells became less and less, and gradually lost their normal cell morphology. After 50℃ and above, all of the proliferation rates of HepG2 cells, LO2 cells, ΔHepG2 cells and ΔLO2 cells were decreased. Compared with the 37℃ group, the differences were statistically significant (P<0.05), and the cells were irreversible damaged. There was no significant difference between the transverse diameters of the sonographic vaporization zones and the actual ablation zones (P>0.05). Nine minutes was considered to be an effective ablation time point since the temperatures in the hyperechoic areas were all above 53℃. Conclusion: The HCC cells within the vaporization zone observed by ultrasound can be damaged irreversibly when they were effectively ablated for over 9 minutes at 105℃ and 200 W.

Pivotal Study of a Novel Motor-Driven Endoscopic Ablation System.

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Modeling Analysis of Thermal Lesion Characteristics of Unipolar/Bipolar Ablation Using Circumferential Multipolar Catheter

The circumferential multipolar catheter (CMC) facilitates pulmonary vein isolation (PVI) for the treatment of atrial fibrillation by catheter ablation. However, the ablation characteristics of CMC are not well understood. This study uses the finite element method to conduct a comprehensive analysis of the ablation characteristics of multielectrode unipolar/bipolar (MEU/MEB) modes of the CMC. A three-dimensional computational model of the CMC, including blood, myocardium, connective tissue, lung, and muscle, was constructed. The method was validated by comparing the results of an in vitro experiment with the simulation. Both ablation modes could create contiguous effective lesions, but the MEU mode created a deeper and broader lesion volume than the MEB mode. The MEB mode had an overall higher average temperature field and allowed faster formation of the effective contiguous lesion. The lesion shape tended to be symmetric and spread downward and superficially in the MEU mode and MEB mode, respectively. Results from the simulation for validation agreed with the in vitro experiment. Different ablation trends of the MEU and MEB modes provide different solutions for specific ablation requirements in clinical applications. The MEU mode suits transmural lesion in thick tissue around pulmonary veins (PVs). The MEB mode profits fast and durable creation of circumferential PVI. This study provides a detailed performance analysis of CMC, thereby contributing to the theoretical knowledge base of application of PVI with this emerging technology.

Switching Monopolar Mode for RF-Assisted Resection and Superficial Ablation of Biological Tissue: Computational Modeling and Ex Vivo Experiments

Radiofrequency (RF)-based monopolar (MM) and bipolar mode (BM) applicators are used to thermally create coagulation zones (CZs) in biological tissues with the aim of destroying surface tumors and minimizing blood losses in surgical resection. Both modes have disadvantages as regards safely and in obtaining a sufficiently deep coagulation zone (CZ). In this study, we compared both modes versus a switching monopolar mode (SMM) in which the role of the active electrode changes intermittently between the two electrodes of the applicator. In terms of clinical impact, the three modes can easily be selected by the surgeon according to the surgical maneuver. We used computational and experimental models to study the feasibility of working in MM, BM, and SMM and to compare their CZ characteristics. We focused exclusively on BM and SMM, since MM only creates small coagulation zones in the area between the electrodes. The results showed that SMM produces the deepest CZ between both electrodes (33% more than BM) and SMM did not stop the generator when an electrode lost contact with the tissue, as occurred in BM. Our findings suggest that the selective use of SMM and BM with a bipolar applicator offers greater advantages than using each type alone.

&lt;p&gt;Novel Management of Rhinophyma by Patterned Ablative 2940nm Erbium:YAG Laser&lt;/p&gt;

IntroductionRhinophyma is a cosmetic disorder that causes emotional distress if the symptoms are extensive or obvious enough. Treatment options range from topical antibiotics or isotretinoin, surgical resection, cryosurgery, electrocautery, dermabrasion and more recently laser therapy. With the limitations of surgical techniques, lasers gained popularity for treating rhinophyma. However, laser ablation is invasive and can lead to side effects and prolonged downtime. Fractional photothermolysis (FP) was introduced to overcome the limitations posed by conventional ablative lasers. To the best of our knowledge, there are no previous studies to evaluate the use of Er:YAG in an ablative mode with a fractional handpiece for the treatment of rhinophyma.Aim of the WorkThe goal of this study was to evaluate the efficacy and safety of fractional ablative 2940 nm Er:YAG laser for the treatment of mild to moderate rhinophyma.Patients and MethodsSixteen patients having mild to moderate rhinophyma were treated with fractional ablative 2940 nm Er:YAG laser. All patients received 4 laser treatments and were followed up over the following 3 months. An additional follow-up appointment 6 months after the last session was arranged to detect any signs of recurrence.Outcome MeasuresPatient questionnaire was used to evaluate patient subjective satisfaction. Objective evaluation was performed by a blind assessment of clinical photographs that were taken before and 3 months after the final treatment by two independent blinded evaluators.ResultsPatient questionnaire taken 3 months after last treatment revealed that 8 patients (50%) were “very satisfied”, 4 patients (25%) were satisfied, and 4 patients (25%) were somewhat satisfied. None of the patients assessed their results as not satisfying.ConclusionIn conclusion, the use of patterned ablative Er:YAG laser with a PS01 handpiece and parameters used in this study comprise an effective tool for treatment of mild to moderate rhinophyma with rapid postoperative recovery compared with conventional surgical procedures and other ablative lasers.

Thulium fiber laser: The new kid on the block.

Laser technology in urology is currently used for both stone lithotripsy and prostate enucleation. Thulium fiber laser (TFL) is a novel laser, with initial studies showing potential benefits over other lasers both in terms of its effectiveness and safety profile. In the first part of this review, a descriptive analysis of the theoretical concepts behind TFL was performed. This part focused on the physics and laser parameters as applied to the clinical practice. These were interpreted in the context of other lasers, namely, the Holmium:YAG laser to highlight the theoretical advantages as well as potential pitfalls offered by the TFL. In the second part of the review, a narrative synthesis of in-vitro studies regarding TFL and its modifications is performed assessing stone-related parameters, namely, ablation rate, operative time retropulsion, and safety. TFL achieved high ablation rates in most studies and performed better than Holmium:YAG laser across a range of different settings and ablation modes when the two lasers were compared. Moreover, its ability to use low pulse energy ensures minimal stone retropulsion with the retropulsion threshold estimated to be 2-4 times higher than that of Holmium:YAG laser. From a safety viewpoint, TFL poses no additional risks than other lasers, although it does potentially lead to slightly higher temperatures in the surrounding tissues during lithotripsy. The unique properties of TFL have made it an attractive alternative to conventional laser techniques currently used in urology. Clinical studies are required before its application can become more widespread.

Temperature-Controlled Catheter Ablation for Paroxysmal Atrial Fibrillation: the QDOT-MICRO Workflow Sttudy.

A novel QDOT MICRO (Biosense Webster, Inc., Irvine, CA) catheter with optimized temperature control and microelectrodes was designed to incorporate real-time temperature sensing with contact force detection and microelectrodes to streamline ablation workflow. The QDOT-MICRO feasibility study evaluated the workflow, performance, and safety of temperature-controlled catheter ablation in patients with symptomatic paroxysmal atrial fibrillation with conventional ablation setting. This was a non-randomized, single-arm, first-in-human study. The primary outcome was pulmonary vein isolation (PVI), confirmed by entrance block after adenosine and/or isoproterenol challenge. Safety outcomes included incidences of early-onset primary adverse events (AEs) and serious adverse device effects (SADEs). Device performance was evaluated via physician survey. All evaluated patients (n = 42) displayed 100% PVI. Two primary AEs (4.8%) were reported: 1 pericarditis and 1 vascular pseudoaneurysm. An additional SADE of localized infection was reported in 1 patient. No stroke, patient deaths, or other unanticipated AEs were reported. Average power delivered was 32.1±4.1 W, with a mean temperature of 40.8°C±1.6°C. Mean procedure (including 20-minute wait), fluoroscopy, and radiofrequency application times were 129.8, 6.7, and 34.0 minutes, respectively. On device performance, physicians reported overall satisfactory performance with the new catheter, with highest scores for satisfaction and usefulness of the temperature indicator. Initial clinical experience with the novel catheter showed 100% acute PVI success and acceptable safety and device performance in temperature-controlled ablation mode. There were no deaths, stroke, or unanticipated AEs. Fluoroscopy and procedural times were short and similar or better than reported for prior generation catheters.

Fractional Carbon Dioxide Laser is Effective in Amelioration of Pruritus in Primary Cutaneous Amyloidosis: A Clinical and Biochemical Study.

Primary cutaneous amyloidosis (PCA) is a pruritic disease characterized by amyloid deposition in the skin. Interleukin-31 (IL-31) is a pruritus-mediating cytokine. Fractional carbon dioxide (CO2 ) laser has shown efficacy in the treatment of PCA regarding the clinical appearance, histological pattern, and pruritus. The aim of this study is to assess the effect of fractional CO2 laser on pruritus associated with PCA, and analyze whether this effect is related to IL-31 and IL-31 receptor (R) expression. The study included 24 patients with PCA and 24 healthy controls. Each patient received four fractional CO2 laser sessions, 4 weeks apart, using the superficial ablative mode. Skin biopsies were taken from patients before and after treatment, as well as controls, for assessment of IL-31 and IL-31R by real-time polymerase chain reaction. Treatment resulted in significant improvement of all clinical parameters, including pruritus (P < 0.001). Patients before treatment had significantly higher IL-31 and IL-31R than controls (P = 0.000 for both). In addition, there was a statistically significant decrease in IL-31 and IL-31R after treatment than their values before treatment (P = 0.000 for both). This study confirms the therapeutic efficacy of fractional CO2 laser in treatment of PCA. Reduction of IL-31 and its receptor seems to be one of the involved mechanisms; however, its relation to improvement of pruritus is still not clear. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Dynamic characterization of indocyanine green-assisted dental caries ablation with continuous diode laser using thermal imaging and fluorescence spectroscopy.

We describe the time-resolved thermal changes in indocyanine green (ICG)-assisted diode laser ablation of dental caries as a potential technique for painless treatment based on the selective photoabsorption and controlled photothermal ablation. Static ablation mode produced a higher temperature rise compared with scanning mode due to localized accumulation of heat. A temperature rise between 45-80 and 70-95°C was obtained after 20s that corresponded to 29 and 80Wcm-2, respectively. The temperature of the tooth surface increased by irradiation time, and it behaved linearly up to 70°C at 29 and 80Wcm-2. A maximum ablation per area of about 0.3 and 0.45mgcm-2 was achieved after 80s exposure at 29 and 80Wcm-2, respectively. A statistically significant difference is observed in mean carious teeth weight at various exposure times between low and high irradiances. A thermal penetration depth of 0.8-9mm is determined for 1-100s of exposure time. The IR thermal imaging of ICG temperature as a function of exposure time showed a linear increase for 60s beyond which it deviated. The laser-induced fluorescence spectroscopy indicated that the ICG quality can be altered during the course of irradiation, which in our case, it corresponded to ≈ 78% loss of signal within 23min of exposure. The caries removal experiment was performed within 100s corresponding to ≈ 7% loss. We believe that the application of the above-combined technique can be utilized as a monitoring device to control the ablation interaction process.

Directional autonomous water flow in laser-engineered microfluidic gradient structures on polymethylmetacrylate-coated steel surface

Autonomous directional water flow was demonstrated on a laser-microstructured steel-supported polymethylmetacrylate (PMMA) film with a surface tension gradient. For this purpose, a 4 μm-thick PMMA layer on AISI 304 steel surface was raster-scanned in air in ablative mode by a 1064 nm, 100 ns laser beam in a number of lines, with the amount and topography of ablated PMMA analyzed by optical microscopy, profilometry and IR spectroscopy. Such scanning, performed at increasing incident fluences, produced a series of chemically and topographically modified, differently water-wet neighbouring mm-sized spots, autonomously driving single-droplet water flow along the surface tension (contact angle) gradient.

Effect of Laser Processing on Surface Properties of Additively Manufactured 18-Percent Nickel Maraging Steel Parts

In the present work, the experimental study on laser processing of additively manufactured (AM) maraging steel part surface was conducted. Nanosecond pulsed laser at ablation mode was used for surface modification in oxidizing atmosphere. The morphology, roughness, elemental and phase composition, microhardness and tribological properties of the processed surfaces were investigated. The obtained results revealed that pulsed laser processing under the ablation mode in air allows obtaining modified surface with uniform micro-texture and insignificant residual undulation, providing 3 times lower roughness as compared with the as-manufactured AM part. The intensive oxidation of surface during laser processing results in formation of the significant oxides amount, which can be controlled by scanning speed. Due to the presence of the oxide phase (such as Fe2CoO4 and Ti0.11Co0.89O0.99), the hardness and wear resistance of the surface were significantly improved, up to 40% and 17 times, respectively. The strong correlation between the roughness parameter Ra and mass loss during the tribological test testifies the significant role of the obtained morphology for the wear resistance of the surface.

PD08-03 EFFECTS OF DIFFERENT RADIOFREQUENCY ABLATION MODES ON NORMAL RENAL TISSUE AROUND THE ABLATION ZONE

You have accessJournal of UrologyKidney Cancer: Localized: Ablative Therapy (PD08)1 Apr 2020PD08-03 EFFECTS OF DIFFERENT RADIOFREQUENCY ABLATION MODES ON NORMAL RENAL TISSUE AROUND THE ABLATION ZONE Linfang Yao*, Wenmin Cao, Wei Wang, Wei Chen, Jiong Shi, Xingqun Zhao, and Hongqian Guo Linfang Yao*Linfang Yao* More articles by this author , Wenmin CaoWenmin Cao More articles by this author , Wei WangWei Wang More articles by this author , Wei ChenWei Chen More articles by this author , Jiong ShiJiong Shi More articles by this author , Xingqun ZhaoXingqun Zhao More articles by this author , and Hongqian GuoHongqian Guo More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000835.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To explore the effects of radiofrequency ablation "slow" or "fast" mode on normal renal tissue around the ablation zone. METHODS: The animal model of rabbit renal VX2 tumor was established. Radiofrequency ablation of rabbit renal VX2 tumors was performed in a "slow" or "fast" mode. The thermocouple temperature measurement system(NATIONAL INSTRUMENTS Company, USA) monitored the temperature changes of the ablation zone and the renal tissue around the ablation zone during the radiofrequency ablation. The formation and range of radiofrequency ablation were monitored in real time by B-ultrasound imaging system (Flex Focus 800 (BK Medical).Conventional pathological hematoxylin-eosin staining was used to observe the necrosis. Cell necrosis and apoptosis were detected by trypan blue staining and TUNEL(terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling). The change of cell microstructure was examined under a transmission electron microscope. RESULTS: Radiofrequency ablation of rabbit renal VX2 tumors in either "slow" or "fast" mode formed an ideal range of ablation zone to cover the tumor.The average temperature within the ablation area reached 80 degree centigrade and a significant ablation zone could be formed. But the "fast" mode of radiofrequency ablation often leaded to a temperature of more than 60 degree centigrade in normal kidney tissue around the ablation zone. While under a "slow" mode, the temperature of normal surrounding kidney tissue was about 40 degree centigrade. The "fast" mode of radiofrequency ablation could easily lead to damage to normal renal tissue around the ablation zone followed with degeneration and necrosis. Trypan blue staining was positive in the damaged tissue cells. Apoptosis index and mitochondrial injury were increased. While the "slow" mode of radiofrequency ablation did not cause significant damage to normal renal tissue surrounding the ablation zone. CONCLUSIONS: Radiofrequency ablation of renal tumors should be performed in a "slow" mode to minimize damage to normal renal tissue around the ablation zone. Source of Funding: This work was supported by the National Natural Science Foundation of China (Grant No. 81972388, 81772710) , Nanjing health science and technology development special fund project (YKK18076), Jiangsu postdoctoral research fund (1701023B), the Project of Invigorating Health Care through Science, Technology and Education, Jiangsu Provincial Key Medical Discipline (Laboratory) (ZDXKB2016014). © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e168-e168 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Linfang Yao* More articles by this author Wenmin Cao More articles by this author Wei Wang More articles by this author Wei Chen More articles by this author Jiong Shi More articles by this author Xingqun Zhao More articles by this author Hongqian Guo More articles by this author Expand All Advertisement PDF downloadLoading ...

Influence of double pulse ablation on the film topography in picosecond pulsed laser deposition of nickel

An approach to achieve co-axial picosecond laser pulsed pair is proposed. Instead of introducing additional optical devices, this method involves the adjustment of switching-out dynamics in the regenerative amplification process. Experimental results concerning the dependence of laser output behavior on the duration of the quarter-wave voltage applied on the Pockels cell are reported. The influence of ablation mode (single pulse or double pulse) on the morphology of deposited Nickel-films is studied. A significant improvement in the surface morphology with the double pulse mode is observed. Fewer nanoparticles are observed and the thin film appears to be smoother with lower roughness.

Capabilities of automated LA-ICP-TOFMS imaging of geological samples

A new software control system enables adaptable and task-specific ablation modes for LA-ICP-TOFMS imaging.

Infrared Laser Ablation of Gamma-Irradiated Polyamide-6

Irradiation of polyamide-6 (PA) with γ-rays reduces its resistance to subsequent IR laser radiation. The average rate of laser ablation of PA, preliminarily irradiated with γ-rays at a dose above ~300 kGy, is almost dose-invariant and is 30% higher than that of the initial unirradiated polymer. The pattern of the dose dependence of the laser ablation rate for the samples pre-irradiated with a dose of 3.24 MGy at a dose rate of 4.2 Gy/s is mixed in character, varying from the shape characteristic of the initial polymer at the initial stage to the shape typical of the maximum radiation dose in the stationary laser ablation mode. One of the products of PA laser ablation is a dispersed polymer, consisting of nano- to micrometer-sized particles, the size range of these particles shifting toward smaller values with an increase in the γ radiation dose, a trend that is explained by a decrease in melt viscosity.

Temperature-Controlled Radiofrequency Ablation Using Irrigated Catheters: Maximizing Ventricular Lesion Dimensions While Reducing Steam-Pop Formation.

The goal of this study was to examine the safety and efficacy of radiofrequency ablation (RFA) with irrigated catheters operated in a temperature-controlled mode for ventricular ablation. Techniques to increase RFA dimensions are associated with higher risk for steam-pops. A novel irrigated catheter with circumferential thermocouples embedded in its ablation surface provides real-time surface temperature data. This study hypothesized that RFA operated in a temperature-controlled mode may allow maximizing lesion dimensions while reducing the occurrence of steam-pops. RFA with an irrigated catheter incorporating surface thermocouples was examined in 6 swine thigh muscle preparations and 15 beating ventricles at higher (50 W/60 s, Tmax50oC) and lower (50 W/60 s, Tmax45oC) temperature limits. Biophysical properties, lesion dimensions, and steam-pop occurrence were compared versus RFA with a standard catheter operated in power-control mode at higher (50 W/60 s) and lower (40W/60 s) power, and additionally at high power with half-normal saline (50 W/60 s). In the thigh muscle preparation, lesion depth and width were similar between all groups (p=0.90 and p=0.17, respectively). Steam-pops were most frequent with power-controlled ablation at 50 W/60s (82%) and least frequent with temperature-controlled ablation at 50 W/60 s, Tmax45oC (0%; p<0.001). In the beating ventricle, lesiondepth was comparable between all RFA settings (p=0.09). Steam-pops were most frequent using power-controlled ablation at 50 W/60s (37%) and least frequent with temperature-controlled ablation at 50 W/60 s, Tmax45oC (7%; p<0.001). Half-normal saline had no incremental effect on lesion dimensions at 50W in either the thigh muscle or the beating heart. RFA using a novel irrigated catheter with surface thermocouples operated in a temperature-controlled mode can maximize lesion dimensions while reducing the risk for steam-pops.

Uranium quantification of oak tree rings (Quercus petraea) from a former uranium mining site by High Resolution Inductively Coupled Plasma Mass spectrometry in Laser Ablation and Solution modes

Tree ring proxies are employed in dendroanalysis as a valuable tool for evaluating past anthropogenic contamination. A wide variety of analytical methods are used to quantify tree ring content for a broad spectrum of chemical elements. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is often used to investigate element concentrations in the tree rings. However, several issues regarding the representativeness of laser ablation measurements for trace elements have to be addressed before definitive conclusions can be drawn. In this study, High Resolution (HR)-ICP-MS has been implemented to analyze the trace concentration of uranium (U) in annual growth rings of oak trees (Quercus petraea) using both laser ablation (LA) and solution modes. The three tree samples taken for the present study were located upstream (with respect to the hydrologic system) of a former uranium mine site at Rophin (Puy de Dôme, France), where mining operations were performed between 1949 and 1958. According to the LA-HR-ICP-MS technique, two-dimensional quantitative (2D) mapping of uranium has developed to study the spatial distribution of uranium at the tree ring surface. A strong heterogeneity was observed, leading to an average uranium concentration with high uncertainty (50–66%). Pressed pellets of the standard reference material, NIST1570a spinach leaves and uranium doped cellulose powder were adopted as the uranium standards for quantification. No agreement was found between uranium concentrations measured after acid digestion and the values obtained by laser ablation. This comparison highlights the limitations of laser ablation technique; hence the solution mode should be preferred for quantifying uranium trace concentrations in tree rings. However, low uncertainty (< 9%) was found with the HR-ICP-MS solution, this result should be compared with the deviation observed both at the tree scale (≈ 40%) and across the ≈ 10 m sampling area (≈ 50%).

Strengthening mechanism of Nd: Yag laser shock peening for commercially pure titanium (CP-TI) on surface integrity and residual stresses

Abstract In the present work, an attempt has been made to investigate the effect of generating shock waves through direct and confined ablation modes of plasma method of massive laser shock peening (MLSP) on surface integrity of cast dumbbell shaped and cylindrical cast specimens of commercially pure titanium (CP-Ti) and to compare with those of untreated CP-Ti. The MLSP is usually performed in a massively peening mode to induce uniform compressive residual stress and surface deformation across the entire specimens. After MLSP, tensile testing was carried out to obtain the tensile strength, modulus of elasticity and percentage elongation. The microstructural and surface topography investigations of the laser shock peened material were carried out using digital, optical microscopy and SEM equipped with an energy dispersive spectrometer (EDS) and XRD. The results show that laser shock peened with confined ablation make the surface of CP-Ti with improved change in microstructure, increase in tensile strength, microhardness (73.08%), surface roughness and compressive residual stresses (−420 MPa) which prolongs the mastication ability and dimensional stability of dental implant restorative materials.

P2844Novel temperature guided irrigated ablation catheter: reproducibility of procedural efficiencies and acute success to isolate the pulmonary veins from two multicenter, feasibility studies

Abstract Background/Introduction The novel catheter with 6 thermocouples for real-time temperature monitoring during irrigated radiofrequency ablation was designed to potentially enhance safety and effectiveness of the Smart Touch Surround Flow (STSF) catheter by incorporating real-time temperature sensing. A supplementary, novel algorithm was developed to modulate power to maintain target temperature during high power/short duration ablation (90W, 4s). Purpose This sub-analysis was performed to examine consistency and reproducibility of the procedural efficiencies and acute success of the novel catheter with optimized temperature control and microelectrodes in treating paroxysmal atrial fibrillation (PAF) across multiple sites from two initial feasibility studies, in standard (QMODE) and high power/short duration (QMODE+) temperature-control ablation modes. Methods The QDOT-MICRO (QMODE, NCT02944968; N=42) and QDOT-FAST (QMODE+, NCT03459196; N=52) studies were both prospective, non-randomized multi-center, clinical investigations completed across 6 and 7 centers, respectively, in Europe. Procedural efficiencies and acute success (PVI via entrance block) was examined across sites within the study. Results In the QDOT-MICRO study, median procedure time (105–155 min), RF ablation time (27.7–39.5 min), and fluoroscopy times (2.2–8 min) during QMODE ablation were similar across the 6 sites. In QMODE+ ablation, median procedure time, RF ablation time, and fluoroscopy times all fall within (84–134 min), (4.8–9.7 min) and (1.1–9.6 min), respectively, across the 7 sites. Fluid delivery by the study catheter was low in both studies: QDOT-MICRO 547±278mL (mean ± SD); QDOT-FAST 382±299. mL (mean ± SD); which is 39.1 and 57.4% lower, respectively, than reported in the SMART SF trial. Esophageal temperature probe was used in the majority of patients (30/42 for QDOT MICRO and 51/52 for QDOT-FAST). Acute PVI was successful in 100% of patients in both studies with no deaths or unanticipated AEs. Conclusion(s) In both feasibility studies, procedural efficiencies were reproducible across study sites in both QMODE and QMODE+, with 100% acute success and good safety outcomes. Efficiencies are likely to improve with further experience. These results need to be confirmed in larger trials. Acknowledgement/Funding Both Studies are Company Sponsored Studies funded by Biosense Webster, Inc.

Single-Fiber Laser Ablation in Treating Selected Metastatic Lymph Nodes of Papillary Thyroid Carcinoma and Benign Cold Thyroid Nodules-Preliminary Results.

Background and ObjectivesTo evaluate the feasibility and efficacy of single‐fiber laser ablation (LA) under ultrasound guidance and appropriate ablation modes in the treatment of selected metastatic lymph nodes of papillary thyroid carcinoma (PTC) and benign cold thyroid nodulesStudy Design/Materials and MethodsA total of 18 patients (consisting of 8 patients with 18 metastatic lymph nodes of PTC and 10 patients with 10 benign cold thyroid nodules) each underwent one session of single‐fiber LA under ultrasound guidance. On the basis of the sizes of the nodules, the ablation modes were chosen accordingly. The single‐dot ablation mode was used in the nodules with three orthogonal diameters measuring no greater than 10 mm in diameter, with a dot, a level and an insertion. The double‐dots overlapping ablation mode was used in the nodules with the largest diameters measuring greater than 10 mm (in which the nodules measured no more than 15 mm in diameter and with the other two perpendicular diameters measuring no greater than 10 mm in diameter) with two dots, a level and two insertions. The multiple levels and dots overlapping ablation mode was used in the nodules with the three orthogonal diameters all measuring larger than 10 mm, with multiple dots, levels and insertions.ResultsAfter 12 months of follow‐up in the treated nodules of the metastatic lymph nodes of PTC and benign cold thyroid nodules, the mean baseline volumes decreased from 0.29 ± 0.12 to 0.03 ± 0.03 ml and 3.85 ± 0.64 to 1.1 ± 0.37 ml, respectively, and the mean volume reduction ratios (VRRs), which was calculated as {[(initial volume−final volume) × 100%]/initial volume}, were 90.3 ± 7.6% and 72 ± 5.8%, respectively. There were six ablative zones that completely disappeared, whereas the ablative zones that still existed presented as scar‐like areas or small hyperechoic areas that were compatible with scar tissue among the 18 malignant nodules at the last follow‐up.ConclusionsSingle‐fiber LA under ultrasound guidance, with the appropriate ablation modes, is feasible and effective for the treatment of selected metastatic lymph nodes of PTC and benign cold thyroid nodules. This study suggests that single‐fiber LA may be applied to selected cases with appropriate ablation modes. Lasers Surg. Med. 2019 © 2019 Wiley Periodicals, Inc.