Combined Radiofrequency Research Articles

9:21 AM Abstract No. 164 - Pathological comparison of radiofrequency and microwave ablation in combination with transarterial chemoembolization in the treatment of hepatocellular carcinoma

Pathological comparison of radiofrequency and microwave ablation in combination with transarterial chemoembolization in the treatment of hepatocellular carcinoma R. Vasnani, M. Ginsburg, T. Doshi, A. Kozlov, J. Hart, H. Te, T. VanHa; Radiology, University of Chicago, Chicago, IL; University of Florida College of Medicine, Gainesville, FL; Pathology, University of Chicago, Chicago, IL; Medicine, University of Chicago, Chicago, IL

Preparation of double layer porous films of Titanium/Titanium oxide for photoelectrochemical cells application

Double layer nanoporous films of Titanium (Ti)/Titanium oxide (TiO2) were fabricated by a combined radio frequency sputtering and sol–gel combustion method and investigated with respect to its photo-anode properties of transparent conductive oxide-less dye-sensitized solar cells (TCO-less DSCs). The porous Ti layer can collect electrons from the TiO2 layer and allows the ionic diffusion of iodide ion/triiodide ion (I-/I3-) through the hole. The porous Ti layer with low sheet resistance (∼2.7Ω/sq.) can be prepared by substrate temperature 300°C under RF power 300W and Ar gas pressure 5mTorr. The Ti/TiO2 double layers prepared by combined RFS/SGC method show the good impedance characteristics. The efficiency (η) of prepared TCO-less DSCs sample is 5.73% [fill factor (ff): 0.76, open circuit voltage (Voc): 0.71V, short-circuit current density (Jsc): 10.61mA/cm2].

In vitro assessment of a combined radiofrequency ablation and cryo-anchoring catheter for treatment of mitral valve prolapse

Percutaneous approaches to mitral valve repair are an attractive alternative to surgical repair or replacement. Radiofrequency ablation has the potential to approximate surgical leaflet resection by using resistive heating to reduce leaflet size, and cryogenic temperatures on a percutaneous catheter can potentially be used to reversibly adhere to moving mitral valve leaflets for reliable application of radiofrequency energy. We tested a combined cryo-anchoring and radiofrequency ablation catheter using excised porcine mitral valves placed in a left heart flow loop capable of reproducing physiologic pressure and flow waveforms. Transmitral flow and pressure were monitored during the cryo-anchoring procedure and compared to baseline flow conditions, and the extent of radiofrequency energy delivery to the mitral valve was assessed post-treatment. Long term durability of radiofrequency ablation treatment was assessed using statically treated leaflets placed in a stretch bioreactor for four weeks. Transmitral flow and pressure waveforms were largely unaltered during cryo-anchoring. Parameter fitting to mechanical data from leaflets treated with radiofrequency ablation and cryo-anchoring revealed significant mechanical differences from untreated leaflets, demonstrating successful ablation of mitral valves in a hemodynamic environment. Picrosirius red staining showed clear differences in morphology and collagen birefringence between treated and untreated leaflets. The durability study indicated that statically treated leaflets did not significantly change size or mechanics over four weeks. A cryo-anchoring and radiofrequency ablation catheter can adhere to and ablate mitral valve leaflets in a physiologic hemodynamic environment, providing a possible percutaneous alternative to surgical leaflet resection of mitral valve tissue.

Home Hair Removal in All Skin Types with a Combined Radiofrequency and Optical Energy Source Device

Home hair removal devices are available for skin types I to IV. Side effects may limit hair removal in darker-pigmented individuals. To evaluate a home hair removal device using combined radiofrequency (RF) and intense pulsed light (IPL) energy for effectiveness and safety with all skin types (I-VI). Two study designs: effectiveness (treating 94 bilateral patient areas weekly seven times, with one side then receiving three additional treatments at 4-week intervals) and safety (37 patient areas treated every 2-4days for three sessions). Hairs were counted 3months after treatment for the first design and 2months after for the second. In the first study design, 55% hair count reduction was achieved1month after seven treatments to all sites. The side with no further sessions had 43% hair reduction and the side receiving ongoing treatment had 58% reduction after two further treatments. Side effects were transient and minor. In the second study, with 46% of the patients having skin types V/VI, 2months after the procedure there was 44% hair reduction. There were no adverse effects reported. For the first time, a home hair removal device has been shown to be effective and safe in all skin types using a low-energy RF-IPL device.

Additive anti-Tumor Response to the Rabbit VX2 Hepatoma by Combined Radio Frequency Ablation and Toll like Receptor 9 Stimulation

Introduction: Radiofrequency ablation (RFA), a palliative therapeutic option for solid hepatic tumors, stimulates localized and systemic anti-tumor cytotoxic T cells. We studied how far addition of CpG B oligonucleotides, toll like receptor (TLR) 9 agonists, may increase the anti-tumoral T cell response of RFA in the highly aggressive VX2 hepatoma.

Investigation of the effects of a thin dielectric layer on low-pressure hydrogen capacitive discharges driven by combined radio frequency and pulse power sources

Negative hydrogen ion sources, for instance for fusion devices, currently attract considerable attention. To generate the precursors—highly rovibrationally excited hydrogen molecules—for negative hydrogen ions effectively by electron excitation, a thin dielectric layer is introduced to cover the surface of the electrically grounded electrode of two parallel metal plates in a low-pressure hydrogen capacitive discharge driven by combined rf and pulse power sources. To understand the characteristics of such discharges, particle-in-cell simulations are conducted to study the effects that the single dielectric layer would bring onto the discharges. The simulation results show that the dielectric layer leads to a much higher plasma density and a much larger production rate of highly vibrationally excited hydrogen molecules compared to discharges without the dielectric layer on the electrode. Further investigation indicates that the nonlinear oscillation of the electrons induced by the nanosecond-pulse continues until it is finally damped down and does not show any dependence on the pulse plateau-time, which is in stark contrast to the case without the dielectric layer present. The physical reason for this phenomenon is explored and explained.

Effects of combined radiofrequency radiation exposure on levels of reactive oxygen species in neuronal cells

The objective of this study was to investigate the effects of the combined RF radiation (837 MHz CDMA plus 1950 MHz WCDMA) signal on levels of intracellular reactive oxygen species (ROS) in neuronal cells. Exposure of the combined RF signal was conducted at specific absorption rate values of 2 W/kg of CDMA plus 2 W/kg of WCDMA for 2 h. Co-exposure to combined RF radiation with either H2O2 or menadione was also performed. The experimental exposure groups were incubator control, sham-exposed, combined RF radiation-exposed with or without either H2O2 or menadione groups. The intracellular ROS level was measured by flow cytometry using the fluorescent probe dichlorofluorescein diacetate. Intracellular ROS levels were not consistently affected by combined RF radiation exposure alone in a time-dependent manner in U87, PC12 or SH-SY5Y cells. In neuronal cells exposed to combined RF radiation with either H2O2 or menadione, intracellular ROS levels showed no statically significant alteration compared with exposure to menadione or H2O2 alone. These findings indicate that neither combined RF radiation alone nor combined RF radiation with menadione or H2O2 influences the intracellular ROS level in neuronal cells such as U87, PC12 or SH-SY5Y.

Fast and high-resolution quantitative mapping of tissue water content with full brain coverage for clinically-driven studies

An efficient method for obtaining longitudinal relaxation time (T1) maps is based on acquiring two spoiled gradient recalled echo (SPGR) images in steady states with different flip angles, which has also been extended, with additional acquisitions, to obtain a tissue water content (M0) map. Several factors, including inhomogeneities of the radio-frequency (RF) fields and low signal-to-noise ratios may negatively affect the accuracy of this method and produce systematic errors in T1 and M0 estimations. Thus far, these limitations have been addressed by using additional measurements and applying suitable corrections; however, the concomitant increase in scan time is undesirable for clinical studies. In this note, a modified dual-acquisition SPGR method based on an optimization of the sequence formulism is presented for good and reliable M0 mapping with an isotropic spatial resolution of 1×1×1mm3 that covers the entire human brain in 6:30min. A combined RF transmit/receive map is estimated from one of the SPGR scans and the optimal flip angles for M0 map are found analytically. The method was successfully evaluated in eight healthy subjects producing mean M0 values of 69.8% (in white matter) and 80.1% (in gray matter) that are in good agreement with those found in the literature and with high reproducibility. The mean value of the resultant voxel-based coefficients-of-variation was 3.6%.

Multi-layer haemocompatible diamond-like carbon coatings obtained by combined radio frequency plasma enhanced chemical vapor deposition and magnetron sputtering

Radio-frequency Plasma Enhanced Chemical Vapour Deposition (in different methane dilutions) was used to synthesize adherent and haemocompatible diamond-like carbon (DLC) films on medical grade titanium substrates. The improvement of the adherence has been achieved by interposing a functional buffer layer with graded composition TixTiC1-x (x = 0-1) synthesized by magnetron co-sputtering. Bonding strength values of up to ~67 MPa have been measured by pull-out tests. Films with different sp(3)/sp(2) ratio have been obtained by changing the methane concentration in the deposition chamber. Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction were employed for the physical-chemical characterization of the samples. The highest concentration of sp(3)-C (~87 %), corresponding to a lower DLC surface energy (28.7 mJ/m(2) ), was deposited in a pure methane atmosphere. The biological response of the DLC films was assayed by a state-of-the-art biological analysis method (surface enhanced laser desorption/ionization-time of flight mass spectroscopy), in conjunction with other dedicated testing techniques: Western blot and partial thromboplastin time. The data support a cause-effect relationship between sp(3)-C content, surface energy and coagulation time, as well as between platelet-surface adherence properties and protein adsorption profiles.

Adjuvant Liposomal Doxorubicin Markedly Affects Radiofrequency Ablation–induced Effects on Periablational Microvasculature

PurposeTo evaluate the effects of radiofrequency (RF) ablation without and with adjuvant intravenous (IV) liposomal doxorubicin (Doxil) on microvessel morphology and patency and intratumoral drug delivery and retention. Materials and MethodsThere were 133 tumors/animals used in this experiment. First, single subcutaneous tumors (R3230 in Fischer rats and 786-0 in nude mice) were randomly assigned to receive RF ablation alone or no treatment and sacrificed 0–72hours after treatment. Next, combined RF ablation and liposomal doxorubicin (1mg given 15min after RF ablation) was studied in R3230 tumors at 0–72hours after treatment. Histopathologic assessment, including immunohistochemical staining for cleaved caspase-3, heat-shock protein 70, and CD34, was performed to assess morphologic vessel appearance, vessel diameter, and microvascular density. Subsequently, tumors were randomly assigned to receive RF ablation alone, RF ablation and liposomal doxorubicin, or no treatment (control tumors), followed by IV fluorescent-labeled liposomes (a surrogate marker) given 0–24hours after RF ablation to permit qualitative assessment. ResultsRF ablation alone resulted in enlarged and dysmorphic vessels from 0–4hours, peaking at 12–24hours after RF ablation, occurring preferentially closer to the electrode. The addition of doxorubicin resulted in earlier vessel contraction (mean vessel area, 47,539μm2±9,544 vs 1,854μm2±458 for RF ablation alone at 15min; P<.05). Combined RF ablation and liposomal doxorubicin produced similar fluorescence 1hour after treatment (40.88AU/μm2±33.53 vs 22.1AU/μm2±13.19; P = .14) but significantly less fluorescence at 4 hours (24.3AU/μm2±3.65 vs 2.8AU/μm2±3.14; P<.002) compared with RF ablation alone denoting earlier reduction in microvascular patency. ConclusionsRF ablation induces morphologic changes to vessels within the ablation zone lasting 12–24hours after treatment. The addition of liposomal doxorubicin causes early vessel contraction and a reduction in periablational microvascular patency. Such changes would likely need to be considered when determining optimal drug administration and imaging paradigms.

PP131: Development of cell internalizable magnetite nanoparticle as a novel in vivo OSCC combined therapy

Purpose Traditional chemotherapies are still far from satisfactory due to the development of drug resistance and side effects derived from non-specific targeting of healthy normal cells. Recent reports suggest that combined physical and chemical approaches in cancer therapy may have synergistic advantage such as hyperthermia and chemotherapy especially when both approaches are delivered under synchronized manner. In addition, previous studies reported that CD44 plays multiple functions in oral squamous cell carcinoma (OSCC) progression. CD44 can be triggered to internalize by extracellular matrix or antibody and to form the transcriptional complex. Their nuclear translocation could turn on cancer reprogramming genes. In this study, we use this internalization pathway to design a novel hyperthermo-chemotherapy that shuttled the oligonucleotide magnetite nanoparticles from cell membrane to the nucleus. Materials and methods The designed nanoparticle includes a high-saturation magnetization (94 emu/g) magnetite nanocrystals core conjugated with polynucleotide loaded with 5-fluorouracil (5-FU) shells and anti-CD44 mAb. We used two OSCC cell lines (OEC-M1 and HSC-3) and two normal cells (NHOK and HUVEC) in targeting internalization study. We utilized radiofrequency (RF) to induce magnetic hyperthermia (MHT) and evaluated the efficacy in HSC-3 bearing NOD/SCID mice. Results In the in vitro study, we discovered internalization of the membrane CD44 in OSCC cells significantly high than normal cells. The cytotoxicity text showed OSCC cells present significantly lower than normal cells after nanoparticle treatment. We further confirmed nanoparticle treatment combined RF can decrease cell viability in a time-dependent manner. The in vivo results showed only a single dose I.V. injection combined RF treatment caused tumor cell damage and decrease in tumor volume. Conclusion This novel therapy consists of two stages: First, the CD44 induced internalization of the nanoparticle could augment both extra-and intracellular MHT by RF in oral cancer. Second, the 5-FU released during MHT provides effective chemotherapy to retard tumor re-progression. We anticipate such achievements could inspire further nano drug delivery strategy to advance oral cancer therapeutics.

Three dimensional complex plasma structures in a combined radio frequency and direct current discharge

We report on the first detailed analysis of large three dimensional (3D) complex plasma structures in experiments performed in pure rf and combined rf+dc discharge modes. Inductively coupled plasma is generated by an rf coil wrapped around the vertically positioned cylindrical glass tube at a pressure of 0.3 mbar. In addition, dc plasma can be generated by applying voltage to the electrodes at the ends of the tube far from the rf coil. The injected monodisperse particles are levitated in the plasma below the coil. A scanning laser sheet and a high resolution camera are used to determine the 3D positions of about 105 particles. The observed bowl-shaped particle clouds reveal coexistence of various structures, including well-distinguished solid-like, less ordered liquid-like, and pronounced string-like phases. New criteria to identify string-like structures are proposed.

Mechanical, tribological and corrosion properties of CrBN films deposited by combined direct current and radio frequency magnetron sputtering

Cr–B–N films were deposited on stainless steel substrates by a combined direct current and radio frequency (RF) reactive unbalanced magnetron sputtering process using two elemental Cr and one compound BN targets. Boron content in the as-deposited films was qualitatively analyzed by time-of-flight secondary ion mass spectroscopy. Films' microstructure, mechanical and tribological properties were characterized by X-ray diffraction, nanoindentation and pin-on-disk tribometer experiments. Corrosion behavior of the Cr–B–N films was evaluated by electrochemical potentiodynamic polarization method in a 3wt.% NaCl solution. All the films were crystallized into a NaCl-type cubic structure. At lower RF power applied on the BN target (≤600W), films are relatively randomly oriented, and films' crystallinity increased with increasing RF power. With increasing RF power further (≥800W), films became (200) preferentially oriented, and films' crystallinity decreased gradually. With incorporation of a small amount of boron atoms into the CrN films, hardness, wear- and corrosion-resistance were all improved evidently. The best wear and corrosion resistance was obtained for the film deposited with 600W RF power applied on the BN target.

Expression of p53 Protein After Nonablative Rejuvenation: The Other Side of the Coin

Disturbance of p53 expression may play an important role in the pathogenesis of ultraviolet (UV) light-induced skin cancer as well as photoaging. To objectively evaluate the potential effect of nonablative facial rejuvenation on p53 expression. Thirty patients with Fitzpatrick skin type III to IV were divided into five groups. Each group underwent a different nonablative modality: radiofrequency (RF), intense pulsed light (IPL), electro-optical synergy (ELOS) (combined RF and IPL), 1,320-nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, and 2,940-nm erbium-doped (Er):YAG laser minipeel. Skin biopsies were obtained before treatment, by the end of treatment, and 3months after treatment. Biopsies were also taken from 30 controls. Quantitative evaluation of p53 was performed using computer image analysis for immunostained tissues. P53 expression was statistically significantly greater at the end of IPL (p=.02) and ELOS (p=.02) treatments than before treatment but was statistically insignificantly lower (p>.05) 3months after treatment than at the end of treatment. No significant differences (p>.05) were observed in p53 level after RF, 1,320-nm Nd:YAG, and 2,940-nm Er:YAG mini-peel treatments from baseline. The increase in epidermal p53 expression after IPL treatment could increase the risk of skin neoplasia by intense pulsed light-induced DNA damage which may lead to dysregulation of apoptosis and initiation of skin cancer.

Role of surgical resection for multiple hepatocellular carcinomas

To clarify the role of surgical resection for multiple hepatocellular carcinomas (HCCs) compared to transarterial chemoembolization (TACE) and liver transplantation (LT). Among the HCC patients who were managed at Yonsei University Health System between January 2003 and December 2008, 160 patients who met the following criteria were retrospectively enrolled: (1) two or three radiologically diagnosed HCCs; (2) no radiologic vascular invasion; (3) Child-Pugh class A; (4) main tumor smaller than 5 cm in diameter; and (5) platelet count greater than 50 000/mm(3). Long-term outcomes were compared among the following three treatment modalities: surgical resection or combined radiofrequency ablation (RFA) (n = 36), TACE (n = 107), and LT (n = 17). The survival curves were computed using the Kaplan-Meier method and compared with a log-rank test. To identify the patients who gained a survival benefit from surgical resection, we also investigated prognostic factors for survival following surgical resection. Multivariate analyses of the prognostic factors for survival were performed using the Cox proportional hazard model. The overall survival (OS) rate was significantly higher in the surgical resection group than in the TACE group (48.1% vs 28.9% at 5 years, P < 0.005). LT had the best OS rate, which was better than that of the surgical resection group, although the difference was not statistically significant (80.2% vs 48.1% at 5 years, P = 0.447). The disease-free survival rates were also significantly higher in the LT group than in the surgical resection group (88.2% vs 11.2% at 5 years, P < 0.001). Liver cirrhosis was the only significant prognostic factor for poor OS after surgical resection. Clinical liver cirrhosis rates were 55.6% (20/36) in the resection group and 93.5% (100/107) in the TACE group. There were 19 major and 17 minor resections. En bloc resection was performed in 23 patients, multi-site resection was performed in 5 patients, and combined resection with RFA was performed in 8 patients. In the TACE group, only 34 patients (31.8%) were recorded as having complete remission after primary TACE. Seventy-two patients (67.3%) were retreated with repeated TACE combined with other therapies. In patients who underwent surgical resection, the 16 patients who did not have cirrhosis had higher 5-year OS and disease-free survival rates than the 20 patients who had cirrhosis (80.8% vs 25.5% 5-year OS rate, P = 0.006; 22.2% vs 0% 5-year disease-free survival rate, P = 0.048). Surgical resection in the 20 patients who had cirrhosis did not provide any survival benefit when compared with TACE (25.5% vs 24.7% 5-year OS rate, P = 0.225). Twenty-nine of the 36 patients who underwent surgical resection experienced recurrence. Of the patients with cirrhosis, 80% (16/20) were within the Milan criteria at the time of recurrence after resection. Among patients with two or three HCCs, no radiologic vascular invasion, and tumor diameters ≤ 5 cm, surgical resection is recommended only in those without cirrhosis.

Heating patterns of white bread loaf in combined radio frequency and hot air treatment

This research investigated heating uniformities of prepackaged bread loaf using combined radio frequency (RF) and hot air treatments to reduce mold growth. Experiments were conducted in a 6kW, 27.12MHz pilot-scale RF system. Effects of the gap between two RF plate electrodes, horizontal and vertical locations of bread loaf, as well as running speed of conveyor belt were studied. When the bread loaf was located in the center plane between the two electrodes 202mm apart, and on a conveyor belt moving at a speed of 1cm/s to reach a minimum sample temperature of 58°C, the temperature distribution within each slice was relatively uniform, with less than a 5°C difference. The cold spot was located at the core of the bread loaves. Higher surface temperature should be useful to assist in inactivation of molds that are commonly vegetated on the surface of the whole loaf.

Efficacy of Combined Treatment with Medial Branch Radiofrequency Neurotomy and Steroid Block in Lumbar Facet Joint Arthropathy

PurposeTo evaluate the long-term efficacy of combined radiofrequency (RF) neurotomy and steroid nerve block in patients with lumbar facet joint arthropathy. Materials and MethodsCombined RF neurotomy and steroid nerve block was performed in 34 patients with chronic paravertebral low back pain. The diagnosis was confirmed by comparative double diagnostic block of the medial branch with bupivacaine and lidocaine. Under fluoroscopy, RF thermal ablation of the medial branch was performed (at RF needle tip temperature 85°C for 90 seconds), three times for each target nerve. At the end of the procedure, 20 mg of methylprednisolone acetate (sustained-release preparation) was infiltrated on each ablated nerve. Outcome variable was the degree of improvement in pain using visual analog scale (VAS) and numerical rating scale (NRS). Improvement in the quality of life was assessed using the Roland-Morris (RM) questionnaire. The procedure was repeated in cases of unbearable pain (>5 VAS score). ResultsPatients had a mean VAS score of 8.6 before the procedure. Thereafter, VAS score was 0.91 immediately after the procedure and 3.0, 2.8, 3.7, and 3.6 at 1 month, 2 months, 6 months, and 1 year. NRS showed pain relief after the procedure of 85%, 65%, 78%, 62%, and 59.5% at the same time points. RM score was 18 before the procedure, 7.6 at 6 months after the procedure, and 8.5 at 1 year after the procedure. No major complication was noted except local pain in all patients and numbness of the back in six patients after the procedure. ConclusionsCombined RF neurotomy and steroid nerve block produced substantial improvement in terms of long-term pain relief and quality of life.

RADIO FREQUENCY MAGNETIZATION NONVOLATILITY

Long time magnetization thermal switching under small amplitude high frequency excitation is analyzed. Approaches based upon conventional time-dependent energy barrier are not sufficient to describe magnetization nonvolatility under GHz excitations. Methods based upon large angle nonlinear magnetization dynamics are developed for both coherent and noncoherent magnetization switching. This dynamic approach is not only important for fundamental understanding of magnetization dynamics under combined radio frequency excitations and thermal fluctuations, but also critical for practical design of emerging spintronic devices. When applied to spin torque random access memory read operations, as sensing current duration reaches nanosecond, dynamic approach gives a switching probability estimation orders of magnitude different from that obtained from conventional time-dependent energy barrier approach.

Mitigation of acrylamide formation in cookies by using Maillard reaction products as recipe modifier in a combined partial conventional baking and radio frequency post-baking process

This study aimed to mitigate acrylamide formation in cookies by lowering thermal energy input along with certain recipe modifications. Lowering temperature required longer cooking times as expected in order to achieve desired final moisture content. To shorten cooking time, conventional baking was combined with radio frequency post-baking process. Lack of development of surface browning in cookies during lower-temperature baking could be overcome by adding the Maillard reaction products (MRP) into dough. The MRP used to modify dough was prepared by heating a binary mixture of arginine and glucose at 100 °C for 6 h or by overbaking thin dough-layered disks. In comparison with control cookie baked at 205 °C for 11 min, combined conventional baking (205 °C for 8 min) and radio frequency post-drying process (45 s) decreased acrylamide formation in biscuits by up to 50 %. The use of Maillard reaction products to improve the visual acceptability of cookies to the consumer may have applications in food industry.

Using short pulses to enhance the production rate of vibrationally excited hydrogen molecules in hydrogen discharge

Hydrogen discharges driven by the combined radio-frequency (rf)/short pulse sources are investigated using the particle-in-cell method. The simulation results show that the discharge driven additionally by the short pulse can enhance the electron density and modulate the electron energy to provide a better condition for negative hydrogen ion production than the discharge driven by the rf-only source.