Active Tip Research Articles

Output Current and Efficacy of Pulsed Radiofrequency of the Lumbar Dorsal Root Ganglion in Patients With Lumbar Radiculopathy: A Prospective, Double-blind, Randomized Pilot Study

BACKGROUND: Lumbar radicular pain (LRP) is a common but challenging clinical symptom. Pulsed radiofrequency (PRF), a neuromodulation technique that uses short pulses of radiofrequency current, is effective in treating various pain disorders. However, few studies have been conducted on the effects of PRF and its modifying parameters. OBJECTIVES: Our study aimed to determine the intraoperative parameters of PRF of the lumbar dorsal root ganglion (DRG) that are related to clinical effects in patients with LRP unresponsive to transforaminal epidural steroid injections (TFESI). STUDY DESIGN: Prospective double-blind randomized controlled trial, pilot study. SETTING: Single medical center in the Republic of Korea. METHODS: Patients were allocated to one of 2 groups, high-voltage (60 V) or standard-voltage (45 V), according to the preset maximum voltage at which the active tip temperature does not exceed 42°C. Intraoperative parameters, such as output current, sensory threshold, and impedance, were measured. The primary outcomes were radicular pain intensity, physical functioning, global improvement and satisfaction with treatment, and adverse events. The assessments were performed up to 3 months postprocedure. RESULTS: The patients in the standard-voltage group showed significant improvements in the Numeric Rating Scale pain score (P = 0.007) and Oswestry Disability Index (ODI) (P = 0.008) scores at 3 months post-PRF; however, no difference was observed in the high-voltage group. Among the intraoperative parameters, the output current showed a significant negative linear relationship with analgesic efficacy. The output current also showed a significant association with pain intensity (P = 0.005, R2 = 0.422) and ODI score (P = 0.004, R2 = 0.427) at 3 months postprocedure in a multiple regression analysis. The optimal cut-off value of the output current to lower pain intensity after 3 months was 163.5 mA with a sensitivity of 87.5%, specificity of 100%, and an area under the receiver operating characteristic curve value of 0.92 (95% CI. 0.76 – 1.00). LIMITATIONS: Limitations of our study include an imbalance of baseline characteristics, small sample sizes, and short follow-up periods CONCLUSIONS: Lower output currents during PRF application to the lumbar DRG were associated with greater analgesic effects in patients who did not respond to therapeutic TFESI. KEY WORDS: Lumbar radicular pain, pulsed radiofrequency, dorsal root ganglion

Effect of four different mono and multi-wave light-curing units on the Knoop hardness of veneer resin composites

ObjectivesTo evaluate the effect of mono and multi-wave light-curing units (LCUs) on the Knoop hardness of resin-based composites (RBC) that use different photoinitiators. MethodsCentral incisor-shaped specimens 12 mm long, 9 mm wide, and 1.5 mm thick were made from 2 RBCs that use different photoinitiators: Tetric N-Ceram (Ivoclar Vivadent) - and Vittra APS (FGM), both A2E shade. They were light-cured with 4 different LCUs: two claimed to be multi-wave - VALO Grand (Ultradent) and Emitter Now Duo (Schuster); and two were monowave - Radii Xpert (SDI) and Elipar DeepCure-L (3 M Oral Care) using 2 different light exposure protocols: one 40 s exposure centered over the specimen; and two 20 s light exposures that delivered light from two positions to better cover the entire tooth. 16 groups with 10 specimens in each group were made. The Knoop hardness (KH, kg/mm2) was measured at the top and bottom of the specimen in the center and at the cervical, incisal, mesial, and distal peripheral regions. The active tip diameters (mm) and spectral radiant powers (mW/nm) of the LCUs were measured with and without the interposition of the RBC, as well as the radiant exposure beam profiles (J/cm²) delivered to the top of the RBCs. The data was analyzed using Three-way ANOVA and Tukey's tests (α = 0.05). ResultsThe VALO Grand (1029 mW) emitted twice the power of the Radii Xpert (500 mW). The KH values of VI and TN resin composite specimens were significantly affected by the LCU used (p < .001), the measurement location (p < .001), and the surface of the specimen (p < .001). LCUs with wider tip diameters produced greater Knoop hardness values at the peripheries of the 12 mm of long, 9 mm wide specimens. In general, the VALO Grand produced the highest KH values, followed by Elipar DeepCure-L, then by Radii Xpert. The Emitter Now Duo LCU produced the lowest values. Exposing the veneers from two locations reduced the differences between the LCUs and the effect of the measurement location. Only the VALO Grand could fully cover the composite veneer with light when the two locations were used. SignificanceThe light tip must cover the entire restoration to photocure the RBC beneath the light tip.

Model-Optimizing Radiofrequency Parameters of 3D Finite Element Analysis for Ablation of Benign Thyroid Nodules.

Radiofrequency (RF) ablation represents an efficient strategy to reduce the volume of thyroid nodules. In this study, a finite element model was developed with the aim of optimizing RF parameters, e.g., input power and treatment duration, in order to achieve the target volume reduction rate (VRR) for a thyroid nodule. RF ablation is modelled as a coupled electro-thermal problem wherein the electric field is applied to induce tissue heating. The electric problem is solved with the Laplace equation, the temperature distribution is estimated with the Pennes bioheat equation, and the thermal damage is evaluated using the Arrhenius equation. The optimization model is applied to RF electrode with different active tip lengths in the interval from 5 mm to 40 mm at the 5 mm step. For each case, we also explored the influence of tumour blood perfusion rate on RF ablation outcomes. The model highlights that longer active tips are more efficient as they require lesser power and shorter treatment time to reach the target VRR. Moreover, this condition is characterized by a reduced transversal ablation zone. In addition, a higher blood perfusion increases the heat dispersion, requiring a different combination of RF power and time treatment to achieve the target VRR. The model may contribute to an improvement in patient-specific RF ablation treatment.

Stellate Ganglion Ablation by Conventional Radiofrequency in patients with Electrical Storm.

We report a series of patients with Electrical Storm (ES) who underwent bilateral stellate ganglion ablation by using conventional radio frequency (RFA). The procedure was done with fluoroscopic guidance using the COSMAN™ 1A RF Generator and a 22G RF needle (5 cm length and 5 mm active tip). Six patients, four male and two female (mean age 55 ± 7 years and mean LVEF-42 ± 21%) with ES underwent the procedure under fluoroscopic guidance. All patients experienced recurrent ICD shocks or required multiple external defibrillation shocks. There were no procedural complications. All patients survived free of ES at discharge. At a mean follow-up of 22 ± 8months, all were alive free of ES but two patients received appropriate shocks for VT and one patient had VT terminated by ATP. This small series of cases is a proof of concept that neuromodulation by conventional RFA targeting bilateral stellate ganglia appears safe, feasible, and effective in treating selected unstable patients with ES.

Clinical feasibility of radiofrequency ablation using novel adjustable separable electrodes with a multipurpose needle for treating small hepatocellular carcinomas: a prospective single center study

Background The novel separable clustered electrode system with two adjustable active tips (ICAEs) and a fine multipurpose needle (MPN) for in situ temperature monitoring and adjuvant agent injection was developed and validated in an animal study. The purpose of this study was to evaluate the technical efficacy and complication of the novel electrode system for patients who have small HCC. Methods In this prospective, single-center clinical trial, ten participants with 14 small (≤ 2 cm, BCLC 0-A) HCCs referred for RFA were enrolled. A novel electrode system consisting of two ICAEs and one MPN with a thermometer and side holes was used for RFA. The RF energy was delivered using a multichannel RF system combining bipolar and switching monopolar modes. Technical success, efficacy, and complications were evaluated on immediate and one-month follow-up CT. Results Technical success was achieved in 92.9% (13/14) of tumors. One participant withdrew consent after RFA, and technical efficacy was achieved in 91.7% (11/12) of tumors. None showed thermal injury to nontarget organs. All patients were discharged the day after RFA without major complications. The active electrode lengths were adjusted in 60% (6/10) of patients during the procedure to tailor the ablation zone (83.3%, n = 5) or treat two tumors with different sizes (16.7%, n = 1). MPN was capable of continuous temperature monitoring during all ablations (100%, 14/14). Conclusions RFA using a novel electrode system showed acceptable technical efficacy and safety in patients with small HCCs. Further comparative studies are needed for the investigation of the system’s potential benefits compared to conventional electrodes.

Active Fiber Tips With Optoelectronic Integration: State-of-the-Art, Future Trends, and Challenges

The integration of conventional silica optical fibers with optoelectronic materials and electrical structures opens the door to miniaturized and multifunctional all-fiber optoelectronic systems with actively controllable capabilities. The flat endface of an optical fiber tip offers a naturally light-coupling microscopic platform for optoelectronic integration using optimized micro- and nano-fabrication techniques. In recent decades, the increasing demand for active fiber devices has created opportunities to develop various optoelectronic structures on fiber tips, from integrating high-performance single modules for specific applications to integrating multi-function multiple modules for more complex applications. In this paper, we review the rapid development of fiber-compatible fabrication technologies for building optoelectrical circuits on fiber endfaces. Then, we discuss the fast-progressing field of active fiber tips along with its wide applications, including photodetection, modulation, lasing, sensing, and light-emitting. Finally, we discuss challenges and opportunities for future development in this field. We believe that this scheme of active fiber tips will pave the way for next-generation ultracompact optical fiber systems with diverse optical and optoelectronic applications.

Using Physical Activity Tips to Recognize and Cope with Rumination in the Pain Dilemma: Traditional Review

Kas iskelet sistemi ağrılarının, biyopsikososyal bir yaklaşımla ele alınması gerektiği son yıllarda sıkça vurgulanmaktadır. Sözlükte “geviş getirmek” ve “zihinde tekrar tekrar gözden geçirmek” olarak tanımlanan ruminasyon, ağrı, bozukluklar ve yeti yitimi için ortak transdiyagnotik bir süreçtir. Biyopsikososyal olarak ele alındığında ruminasyonun fiziksel sağlığı negatif etkilediği ve kronik ağrı, kardiyovasküler hastalık ve obezite gibi kronik durumlara sahip bireylerde ruminasyon düzeylerinin yüksek bulunduğu bilinmektedir. Patolojik ruminasyonun oluş mekanizması H-EX-A-GO-N teorik modeli ile açıklanmaktadır. H-alışkanlık geliştirme, EX-yürütücü işlev, A-soyut işleme, GO-hedef tutarsızlıkları ve N-olumsuz önyargı olarak tanımlanmaktadır. Bu modelde sıralanan faktörlerin ruminatif alışkanlık geliştirme üzerinde etkili olduğu varsayılmaktadır. Ruminasyonun anlaşılması hem klinikte hem de akademik araştırmalarda önem taşıyabilir. Literatürdeki çalışmalar, ruminasyonun ağrı ile pozitif yönde, fiziksel aktivite ile negatif yönde ilişkili olduğunu ortaya koymaktadır. Ruminasyon düzeyindeki artış ağrıya karşı olumsuz tutum ve genel vücut ağrısını da artırabilmektedir. Ruminasyon seviyesindeki artış aynı zamanda fiziksel aktivite seviyesinde azalma ile sonuçlanabilmektedir. Fiziksel aktiviteyi artırmaya yönelik programlar, fiziksel aktivitenin genel sağlığa olan yaygın olumlu etkilerinin yanı sıra ruminatif eğilimin yıkıcı etkilerine karşı da koruyucu bir görev üstlenebilir. Sonuç olarak, kronik ağrılı popülasyonlarda yapılacak çalışmalar ağrı ve ağrıyı hedef alan müdahalelerin ruminasyon düzeyleri üzerine etkilerinin araştırılması ve ruminasyonun fiziksel aktivite üzerindeki etkilerinin ve mekanizmalarının araştırılması daha etkili müdahale programlarının planlanabilmesi açısından önem taşımaktadır.

PO-05-036 PERCUTANEOUS STELLATE GANGLIA ABLATION IN THE MANAGEMENT OF VTSTORM

VT storm is a clinical emergency associated with high mortality. Neural modulation of the cardiac sympathetic chain, usually in the form of surgical sympathectomy, has shown to be effective in achieving reduction in appropriate ICD shocks and VT episodes. We hypothesised Percutaneous Stellate Ganglion Ablation (SGA) is a safe and effective alternative modality of neuromodulation in patients with VT storm. Patients with ES refractory to standard management, including sedation and mechanical ventilation, antiarrhythmic agents and beta-blockers, underwent bilateral percutaneous SGA. The ablation was performed at 2 levels - C7 and T1, bilaterally, under fluoroscopic guidance using a customized protocol. (Figure) At each site, 3 lesions were delivered sequentially at 50, 55 and 60 deg. C for 90 seconds using a COSMAN RF generator and RF needle electrode of 5cm length and 4mm active tip with ipsilateral Horner’s syndrome being the clinical end-point for successful ablation. Patients were followed up till discharge and as outpatients with periodic device interrogation There were 6 patients with refractory VT storm (4 male & 2 female) with a mean age of 56.5±5.2 years. The VT was monomorphic in 4 and polymorphic in the other 2 patients. The substrate was Ischaemic cardiomyopathy in 2, Non-ischaemic cardiomyopathy in 3 and Hypertrophic cardiomyopathy in 1 patient. The meean LVEF was 35 ± 20%. There were no periprocedural complications. Post-procedure, 2 out of the 6 patients had one episode of Non-sustained VT each in-hospital. All patients were discharged on Amiodarone and Metoprolol. The mean follow-up duration was 15± 3 months. At last follow-up all of them are alive and none of then received any shocks.. One patient had a VT at 42 days after procedUre which was terminated by device using ATP. SGA by RFA is a safe, effective, inexpensive, well-tolerated and minimally invasive procedure for neuromodulation and should be considered in drug refractory ES.

The large GTPase AtGBPL3 links nuclear envelope formation and morphogenesis to transcriptional repression.

Guanylate binding proteins (GBPs) are prominent regulators of immunity not known to be required for nuclear envelope formation and morphogenesis. Here we identify the Arabidopsis GBP orthologue AtGBPL3 as a lamina component with essential functions in mitotic nuclear envelope reformation, nuclear morphogenesis and transcriptional repression during interphase. AtGBPL3 is preferentially expressed in mitotically active root tips, accumulates at the nuclear envelope and interacts with centromeric chromatin as well as with lamina components transcriptionally repressing pericentromeric chromatin. Reduced expression of AtGBPL3 or associated lamina components similarly altered nuclear morphology and caused overlapping transcriptional deregulation. Investigating the dynamics of AtGBPL3-GFP and other nuclear markers during mitosis (1) revealed that AtGBPL3 accumulation on the surface of daughter nuclei precedes nuclear envelope reformation and (2) uncovered defects in this process in roots of AtGBPL3 mutants, which cause programmed cell death and impair growth. AtGBPL3 functions established by these observations are unique among dynamin-family large GTPases.

A randomized controlled study of the long-term efficacy of cooled and monopolar radiofrequency ablation for the treatment of chronic pain related to knee osteoarthritis

BackgroundChronic knee pain due to osteoarthritis (OA) is expected to become more prevalent. Although conventional therapies may provide relief they are not long-lasting. Persistent pain may lead to total knee replacement, which is not free of adverse outcomes. Monopolar and cooled radiofrequency ablation (RFA) of genicular nerves is an effective option. However, either method may provide distinctive results depending on expected lesion size, a key aspect considering the anatomical variability of knee innervations. This prospective, double-blind, randomized controlled trial evaluated the efficacy and durability of knee RFA using a cooled probe or a monopolar probe of comparable diameter. MethodsThis investigator-initiated, post-market, double-blinded, prospective, randomized controlled trial was approved by the Western IRB. 79 subjects with chronic knee pain due to knee OA were enrolled in multiple locations of a single center. 75 subjects were randomized (1:1) into RFA treatment with either a 4 ​mm/17G cooled active tip (CRFA) or a 10 ​mm/16G monopolar active tip (MRFA) using conventional procedures. Primary endpoint was change in knee pain level (100 ​mm VAS score) from baseline at 24-week post-treatment. Other endpoints include change in functionality, global perceived effect, and frequency of adverse events. Evaluation spanned to 52-week post-treatment. Significance of results (p ​< ​0.05) was calculated using standard statistical analyses. ResultsBoth CRFA and MRFA provided significant reduction (41 ​mm and 39 ​mm, respectively) of chronic knee pain at 24-week. At the 52-week visit, reduction in pain level was sustained for CRFA (42 ​mm) but seems to decrease for MRFA (31 ​mm). Improvements in functionality were also significant and sustained with both treatments, although tend to decrease with MRFA at 52-week. Most patients also perceived a very good/good effect of treatments along the duration of the study. ConclusionRFA of knee genicular nerves for the treatment of OA chronic pain is effective for 52 weeks post-ablation when using a CRFA (4 ​mm/17G active tip) or MRFA (10 ​mm/16G active tip). The benefits of CRFA seems to be better sustained beyond 24 weeks than the ones of MRFA, although no significant differences were observed at 52 weeks.

Radiofrequency Ablation for Chronic Lumbar Zygapophyseal Joint Pain Using a V-Shaped Active Tip Needle: An Observational Retrospective Study.

Lumbar zygapophyseal joint dysfunction represents one of the major sources of chronic low back pain. Radiofrequency ablation (RFA) using a V-shaped active tip needle may offer a larger lesion of the medial branch nerves, improving clinical outcome. The aim of our study is to evaluate the efficacy and the feasibility of RFA using V-shaped active tip needles. This is a single-center observational retrospective study. Clinical records were screened and analyzed if they met the following inclusion criteria: adult patients (>18 years), diagnosis of chronic lumbar zygapophyseal joint pain, failure of conservative treatments, ability to provide informed consent for data analysis and publication. Exclusion criteria: lumbar pain not related to zygapophyseal joints, previous spinal/lumbar surgery, incomplete data, absence or withdrawal of informed consent. The primary outcome of the study was a change in pain intensity at follow-up. The secondary outcomes were the evaluation of quality-of-life improvement, the occurrence of adverse events and the impact on post-procedural analgesic consumption. For these purposes, pre- and post-treatment numeric rating scale (NRS), neuropathic pain 4 questions (DN4), EuroQoL - EQ-5D-3L, EQ-VAS, EQ-index and North American Spine Society (NASS) index were retrieved and analysed. Sixty-four patients were included. 7.8% of patients at 1-month (CI95% 0.026, 0.173), 37.5% at 3-month (CI95% 0.257, 0.505), 40.6% at 6-month (CI95% 0.285, 0.536) and 35.9% at 9-month (CI95% 0.243, 0.489) follow-up reported a reduction of more than 80% in NRS Statistical analysis indicated a significant change in NRS, DN4, EQ-index and EQ-5D-VAS (p-value <0.001) at the different time-points. RFA using a V-shaped active tip needle might be a feasible and effective treatment for chronic lumbar zygapophyseal joint pain.

Flow cytometry and chromosome numbers variation in argan tree Argania spinosa (L.) Skeels

Argania spinosa L. Skeels is an endemic species of west-central Morocco, which is characterized by a high diversity of morphological and genetic traits. It constitutes a natural resource for oleo-agro-sylvo-pastoral uses. All conservation and genetic breeding strategies aimed to domesticate argan require a good knowledge of the plant material. However, several studies focused on agronomical, morphological, phytochemical, and molecular characterization, while the cytogenetic aspects were less investigated. The objective of this work is to identify the chromosome number and ploidy level on the national argan collection at the Agadir Regional Agronomic Research Center, Morocco. The determination of the chromosome number was carried out on root tips of germinated seeds collected from five trees genotypes selected on various morphological aspects. As a result, chromosome count on active root tip cells showed variation in the number (2n = 20; 2n = 22; 2n = 24) with a stable ploidy level (2n = 2x) that is confirmed by flow cytometry. These results combine two previous findings (2n=20, 2n=24) and reveal a third existence of twenty-two chromosome. As a conclusion, A. spinosa has three chromosomal numbers which represent the genetic diversity of the chromosomal number that this species exhibits. More studies are required to explain this variation on chromosome numbers for future breeding programs and to avoid incompatibilities.

Preparation of Mitotic Chromosomes with the Squash Technique.

Plant chromosomes are usually obtained from meristematic tissue of active root tips through the conventional squash method. Nevertheless, cytogenetic work usually implies a great effort and some modifications of standard procedures need to be evaluated. In this chapter, we describe our outline for handling chromosomes using the squash method. By using these protocols, high-quality chromosome spreads are obtained, which allow chromosome counting, building karyotypes, and assessing chromosomal landmarks, and enable genome mapping by fluorochrome banding and in situ hybridization techniques.

UV-C light as an alternative for disinfecting orthodontic pliers

Objective: Orthodontists use orthodontic pliers continuously, and these tools have a strong potential for nosocomial infections. This study aimed to compare the efficiency of three methods for disinfecting orthodontic pliers. Material and Methods: The active tips of 26 orthodontic pliers (distal end cutters and Weingart pliers) were contaminated with S. aureus, E. coli, and C. albicans microorganisms, viruses, and spores. The microbial control methods were 70% alcohol disinfection, glass bead sterilization (250 °C dry heat), and ultraviolet light irradiation (250 nm UV-C) for 30 and 60 seconds. The number of colony-forming units (CFU) and plaque-forming units (PFU) was quantified and compared for each microorganism after incubation in culture plates. Results: All tips of the pliers in the groups that received ultraviolet light or were subjected to glass bead sterilization showed a significantly lower number of spores, bacteria, and fungi than their respective control samples (p&lt;0.001). Physical disinfection with UV-C light may represent a reliable alternative compared to other chemical and physical methods due to the increase in microorganisms resistant to chemical products and the emission of harmful by-products after chemical treatment. Conclusion: The tested microbial control methods were effective in the disinfection of orthodontic pliers, making ultraviolet-C light a promising alternative to eliminate microorganisms from pliers. KEYWORDS Biosafety; Contamination; Disinfection; Microorganisms; Ultraviolet light.

Current trends in the technical performance of lumbar zygapophyseal joint interventions

ObjectiveTo survey how interventional pain physicians are currently performing lumbar facet interventions, with an emphasis on fellowship training. DesignSurvey Study. MethodsAn online electronic survey disseminated via Research Electronic Data Capture (REDCap) software to current and expired attending physician members of the Spine Intervention Society (SIS). Responses were stratified by fellowship training type: ACGME Pain Medicine (APM), ACGME Sports Medicine (ASM), Interventional Spine and Musculoskeletal Medicine (ISMM), or None. ResultsAs a whole, a majority of respondents indicated on independent questions they require 2 diagnostic medial branch blocks (MBBs) performed with 0.5 ​cc or less of anesthetic to result in at least 75% pain relief before proceeding with a radiofrequency neurotomy (RFN), performed via parallel approach with 18g or larger needle and 10 ​mm active tip and a lesion of at least 80–85° C and 90–119 ​s of duration. Statistically significant differences as stratified by APM vs ISMM fellowship training included: the use of corticosteroids at the time of RFN (43/79 (54.4%) vs 16/63 (25.4%), typically treating 3 segments or more 22/79 (27.8%) vs 7/73 (9.6%), and MBB volume injectate of ≥ 1 ​cc 22/79 (27.8%) vs 7/63 (11.1%) respectively. ConclusionsThere is largely agreement upon the technical performance of lumbar facet interventions by members of SIS. Physicians who completed an APM fellowship were more likely to report using corticosteroids at the time of RFN, using higher anesthetic volumes and treating 3 or more spinal segments.

Caudal Pulsed Radiofrequency for Distal Symmetrical Polyneuropathy

Background: Numbness, tingling, discomfort, and/or weakness in the toes are symptoms of distal symmetrical polyneuropathy (DSP), which proceeds in a stocking-glove pattern proximally. There is still no particular therapy available. Objective: CPRF (caudal pulsed radiofrequency) is used to treat people who have sensory symptoms. Study Design: This is a prospective study at Alsdr teaching hospital in Iraq-Basra. Methods: CPRF, Boston Scientific G4™ RF Generator, Twenty-four subjects with DSP who were stimulated reported sensory complaints that did not respond to therapy. Under fluoroscopy at S2-3 level, inserted a caudal 21 gauge, 20-mm active tip RF cannula into the epidural space through the sacral hiatus. After the sensory and motor RF, give PRF at 5 Hz for 600 seconds at 45 V. Within the first week of the operation, the impact of activation was examined using a numeric rating scale, which was repeated every three months for the next three months. Patient satisfaction levels were assessed three months following treatment; patients who scored "7" (very good) or "6" (good) on the treatment satisfaction scale were rated fulfilled. Results: Neuropathic pain was effectively diminished after four visits (P&lt; 0.001, test one-factor analysis). Furthermore, three months after receiving CPRF, more than half of the patients had an effective reaction (≥60 percent pain reduction) and were comfortable with the therapeutic outcomes. Limitations: The research included a small number of patients and was only for a brief time. Conclusion: CPRF is a safer, less expensive, and more effective way to treat symptoms.

The Effect of Local Anesthetics and Contrast Agents on Radiofrequency Ablation Lesion Size.

Radiofrequency ablation (RFA) is a validated treatment option for the treatment of chronic pain in patients with lumbar spondylosis. Lesion size has been suggested to correlate with good clinical outcomes. This has created an abundance of scientific interest in the development of products with larger lesion characteristics. Needle characteristics, energy transfer, and heat rate are known to modify lesion size. Here, we demonstrate that common intraoperative solutions, such as lidocaine, iodine, and gadolinium-based products, can also affect lesion shape. To determine whether lidocaine and contrast agents modify lesion characteristics during the performance of monopolar RFA. Controlled, ex vivo study using clinically relevant conditions and pre-injections. Academic institution in a procedural setting. RFA lesion size was compared among six cohorts: 1) lidocaine 1%, 2) lidocaine 2%, 3) iohexol 180, 4) iohexol 240, 5) gadodiamide, and 6) control (no fluid control). Radiofrequency (RF) current was applied for 90 seconds at 80°C via 20-gauge 100-mm standard RFA needles with 10-mm active tips in orgranic chicken breasts without preservative at room temperature (21°C). Twelve lesions were performed for each medication cohort. The length, width, and depth of each lesion were measured. The statistical significance between each medication group and the control group was evaluated by t test. The mean lesion surface area of monopolar RFA without any pre-injection used was 80.8 mm2. The mean surface area of the monopolar RF lesion with a pre-injection of 0.2 mL of 2% lidocaine was 114 mm2, and the mean surface area of the monopolar RF lesion with a pre-injection of 0.2 mL of iohexol240 was 130.6 mm2. The statistical analysis demonstrated that the control group had significantly smaller lesion sizes than did the groups in which lidocaine 2% and iohexol240 were used (P<0.01). There were no statistically significant differences among the groups in which lidocaine 1%, iohexol180, and gadodiamide were used. A notable difference was a 20% longer lesion with iohexol240 compared with the control group and a 20% wider lesion with lidocaine 2% compared with the control group. In vivo anatomy within a human was not used in this study, nor were the chicken breasts heated to physiological temperature. Randomization of pieces of chicken breast did not occur, and thus intrinsic differences among the chicken breast pieces could play a confounding role. Lidocaine 2% and iohexol240, when used as pre-injections in RFAs, were found to be associated with statistically significant increases in lesion surface area. However, RFAs with lidocaine 1%, iohexol180, or gadodiamide were not found to produce a statistically significant difference in lesion size compared with monopolar RFA without the use of injectate.

Radiofrequency Ablation of Recurrent Metastatic Papillary Thyroid Cancer to a Lymph Node

Radiofrequency Ablation of Recurrent Metastatic Papillary Thyroid Cancer to a Lymph Node

Effects of material and piston diameter on the fatigue behavior, failure mode, and stress distribution of feldspathic ceramic simplified restorations

This study evaluated the influence of the piston material (glass fiber-reinforced epoxy resin or stainless steel) and the piston tip diameter (6 or 40 mm) on the fatigue mechanical behavior, failure mode, and stress distribution of feldspathic ceramic simplified restorations. Pistons were machined in glass fiber-reinforced epoxy resin (ER) and in stainless steel (SS), with active tips simulating the curvature radius of 6- or 40-mm diameter spheres. A total of sixty (N= 60) feldspathic ceramic discs (Ø= 10 mm; thickness= 1.0 mm) were adhesively luted onto supporting substrate discs (Ø= 10 mm; thickness= 2.5 mm) and allocated into 4 groups (n= 15) according to the piston used for fatigue testing: ER_6, ER_40, SS_6, SS_40. Afterwards, the specimens were submitted to the cyclic fatigue test (20 Hz frequency; initial load= 100 N; step= 50 N; 10,000 cycles/step, upon specimen failure detection). The collected data were analyzed by two-way ANOVA (α= 0.05) to verify differences by considering ‘piston material’ and ‘piston diameter’ as factors, and their association. In addition, a survival analysis (Kaplan Meier with Mantel-Cox log-rank post-hoc tests) was conducted (α= 0.05). Fractographic and finite element (FEA) analyzes were also performed. ‘Piston material’ (p= 0.040, F= 4.43) and ‘piston diameter’ (p < 0.000, F= 563.21) had a significant influence on the fatigue failure load (FFL) and the number of cycles for failure (CFF) values. Feldspathic restorations showed higher FFL and CFF (p < 0.05) when tested with a 40 mm diameter piston compared to a 6 mm diameter piston (ER_40 and SS_40 > ER_6 > SS_6). In relation to the piston material, ER and SS pistons with 40 mm diameter promoted similar fatigue performance (ER_40: 946.67 N/179,333 cycles = SS_40: 936.67 N/177,333 cycles), while 6 mm diameter groups presented different fatigue performance (ER_6: 440 N; 78,000 cycles > SS_6: 353.3 N; 60,667 cycles). Hertzian cone crack failures were only observed in the groups tested with 6 mm pistons, regardless of piston material. Higher stress concentration on the ceramic surface was observed when using 6 mm diameter pistons, whereas the SS_6 group showed a slight increase in stress concentration in comparison to the ER_6 group. The piston diameter showed an influence on the fatigue behavior, failure mode, and stress distribution of feldspathic ceramic simplified restorations. However, the influence of piston material is only observed when 6 mm diameter pistons are used. The 40 mm diameter pistons led to radial crack, being more appropriate for fatigue test of simplified feldspathic ceramic restorations with a thickness ≤ 1 mm. Whilst the 6 mm diameter pistons should be avoided, once tend to induce Hertzian cone crack failures and to underestimate fatigue performance.

Comparison of mechanical resistance and standardisation between original brand and replica-like endodontic systems.

This study compared the original (ProTaper Next and Reciproc) endodontic systems with their replica-like brands (X File and Only One File) in terms of standardisation, design, phase-transformation behaviour, composition and mechanical behaviour. X File showed greater taper values than ProTaper Next, while Only One File had the greatest tip diameter. Both replica-like files had an active tip and greater dimensions than their reports. There were also significant differences between the original and replica-like systems in terms of their phase-transformation behaviour and the precision of the measurement lines. Only One File showed significantly lower cyclic fatigue and torsional resistance than Reciproc (p < 0.05). There were no significant differences in the cyclic fatigue, torsional resistance and composition of NiTi between X File and ProTaper Next (p > 0.05). Although replica systems show mechanical properties that can be acceptable, they are not consistent in terms of standardisation and design.