Thermal Ablation System Research Articles

Thermal ablation with configurable shapes: a comprehensive, automated model for bespoke tumor treatment

BackgroundMalignant tumors routinely present with irregular shapes and complex configurations. The lack of customization to individual tumor shapes and standardization of procedures limits the success and application of thermal ablation.MethodsWe introduced an automated treatment model consisting of (i) trajectory and ablation profile planning, (ii) ablation probe insertion, (iii) dynamic energy delivery (including robotically driven control of the energy source power and location over time, according to a treatment plan bespoke to the tumor shape), and (iv) quantitative ablation margin verification. We used a microwave ablation system and a liver phantom (acrylamide polymer with a thermochromic ink) to mimic coagulation and measure the ablation volume. We estimated the ablation width as a function of power and velocity following a probabilistic model. Four representative shapes of liver tumors < 5 cm were selected from two publicly available databases. The ablated specimens were cut along the ablation probe axis and photographed. The shape of the ablated volume was extracted using a color-based segmentation method.ResultsThe uncertainty (standard deviation) of the ablation width increased with increasing power by ± 0.03 mm (95% credible interval [0.02, 0.043]) per watt increase in power and by ± 0.85 mm (95% credible interval [0, 2.5]) per mm/s increase in velocity. Continuous ablation along a straight-line trajectory resulted in elongated rotationally symmetric ablation shapes. Simultaneous regulation of the power and/or translation velocity allowed to modulate the ablation width at specific locations.ConclusionsThis study offers the proof-of-principle of the dynamic energy delivery system using ablation shapes from clinical cases of malignant liver tumors.Relevance statementThe proposed automated treatment model could favor the customization and standardization of thermal ablation for complex tumor shapes.Key points• Current thermal ablation systems are limited to ellipsoidal or spherical shapes.• Dynamic energy delivery produces elongated rotationally symmetric ablation shapes with varying widths.• For complex tumor shapes, multiple customized ablation shapes could be combined.Graphical

Visualization of fibroblast activation using 68Ga-FAPI PET/CT after pulmonary vein isolation with pulsed field compared with cryoballoon ablation

BackgroundPulsed-field ablation (PFA) is a novel ablation modality for atrial fibrillation (AF) ablating myocardium by electroporation without tissue-heating. With its different mechanism of tissue ablation, it is assumed that lesion creation is divergent to thermal energy sources. 68Ga-fibroblast-activation protein inhibitor (FAPI) PET/CT targets FAP-alpha expressed by activated fibroblasts. We aimed to assess 68Ga-FAPI uptake in pulmonary veins as surrogate for ablation damage after PFA and cryoballoon ablation (CBA). Methods26 patients (15 PFA, 11 CBA) underwent 68Ga-FAPI-PET/CT after ablation. Standardized uptake values (SUV) and fibroblast-activation volumes of localized tracer uptake were assessed. ResultsPatient characteristics were comparable between groups. In PFA, focal FAPI uptake was only observed in 3/15 (20%) patients, whereas in the CBA cohort, 10/11 (90.9%) patients showed atrial visual uptake. We observed lower values of SUVmax (2.85 ± 0.56 vs 4.71 ± 2.06, P = 0.025) and FAV (1.13 ± 0.84 cm3 vs 3.91 ± 2.74 cm3, P = 0.014) along with a trend towards lower SUVpeak and SUVmean in PFA vs CBA patients, respectively. ConclusionTissue response with respect to fibroblast activation seems to be less pronounced in PFA compared to established thermal ablation systems. This functional assessment might contribute to a better understanding of lesion formation in thermal and PFA ablation potentially contributing to better safety outcomes.

Mechanical confinement promotes heat resistance of hepatocellular carcinoma via SP1/IL4I1/AHR axis

Mechanical stress can modulate the fate of cells in both physiological and extreme conditions. Recurrence of tumors after thermal ablation, a radical therapy for many cancers, indicates that some tumor cells can endure temperatures far beyond physiological ones. This unusual heat resistance with unknown mechanisms remains a key obstacle to fully realizing the clinical potential of thermal ablation. By developing a 3D bioprinting-based thermal ablation system, we demonstrate that hepatocellular carcinoma (HCC) cells in this 3D model exhibit enhanced heat resistance as compared with cells on plates. Mechanistically, the activation of transcription factor SP1 under mechanical confinement enhances the transcription of Interleukin-4-Induced-1, which catalyzes tryptophan metabolites to activate the aryl hydrocarbon receptor (AHR), leading to heat resistance. Encouragingly, the AHR inhibitor prevents HCC recurrence after thermal ablation. These findings reveal a previously unknown role of mechanical confinement in heat resistance and provide a rationale for AHR inhibitors as neoadjuvant therapy.

Untargeted metabolomics profiling in a mouse model of lung cancer treated with thermal ablation

ABSTRACT Thermal ablation is widely used in the treatment of lung cancer and is beneficial for the overall survival of patients in clinic. However, there is barely a priority in which ablation system should be chosen under different periods of tumor progression in lung cancer. The present study investigated different modes of thermal ablation systems in mice with transplanted Lewis lung carcinoma tumors and their various biological effects in local regions using untargeted metabolomics. The results showed that thermal ablation could significantly suppress tumor growth and the differentially expressed metabolites of tumors after ablation relative to untreated tumors concentrated on organic compounds, organic acids and derivatives, nucleosides, nucleotides, and lipids. The upregulated metabolites indicated an inflammatory reaction in the ablation groups at an early stage after ablation. Steroid hormone and tryptophan metabolism, which are associated with immune responses, were modulated after both cryoablation and hyperthermal ablation. Characteristically, the results also indicated that cryoablation suppressed glucose oxidation and carbohydrate metabolism of tumor, while hyperthermal ablation suppressed lipid metabolism of tumor. In conclusion, thermal ablation could inhibit tumor growth under either freezing or heating modes with characteristic different biological effects on tumors.

Treatment of chronic venous disorder: A comprehensive review.

Chronic venous disorder (CVD) is highly prevalent vascular disorder affecting up to 45% of the general population, with clinical manifestations ranging from teleangiectasias to venous leg ulcers (VLUs). We examined the currently available data in order to provide an updated, comprehensive review on treatment options of CVD. We searched MEDLINE, Cochrane, Scopus, EMBASE, ClinicalTrials, and OpenGrey databases for relevant articles in English published until November 2020. Compression treatment is the mainstay of conservative treatment. Pharmacological treatment can provide significant symptomatic relief and hence it should be considered as part of conservative treatment. Transcutaneous Lacer treatment (TCL) is a safe and effective alternative option to sclerotherapy for treatment of C1 stage. High ligation and stripping (HL/S), ultrasound-guided foam sclerotherapy (UGFS), endovenous thermal ablation (EVTA) systems and non thermal non tumescent ablation (NTNT) systems are safe and efficacious first-line options for treatment of saphenous insufficiency. Interventional treatment of co-existing incompetent perforator veins (IPVs) is not supported by contemporary evidence. Regarding deep venous insufficiency (DVI), treatment of symptomatic femoroiliocaval occlusive venous disease refractory to conservative treatment with percutaneous transluminal venoplasty stenting has produced encouraging results.

Prospective comparative study of different endovenous thermal ablation systems for treatment of great saphenous vein reflux

ObjectiveThe aim of our study was to compare three different endovenous thermal ablation (EVTA) modalities in the treatment of great saphenous vein (GSV) incompetence. MethodsWe performed a single-center, prospective, comparative cohort study that included consecutive patients undergoing EVTA of the GSV. Patients were treated with either segmental radiofrequency ablation (sRFA) or endovenous laser ablation (EVLA) with a 1470-nm dual radial fiber or with a 1470-nm jacket-tip fiber. The clinical classification CEAP (clinical, etiologic, anatomic, pathophysiologic), 10-cm visual analog scale scores for pain, Venous Clinical Severity Scores (VCSSs), and chronic venous insufficiency quality-of-life questionnaire (CIVIQ-20) scores were recorded. The primary outcome was clinical success, which was defined as the absence of reflux or recanalization of the GSV and procedure-related complications, assessed at 7 and 30 days and 1 year postoperatively. The secondary outcomes were the assessment of postoperative pain using the VAS and improvement in the VCSSs and CIVIQ-20 scores. ResultsA total of 153 patients (160 limbs) had undergone sRFA (sRFA group; n = 53 limbs), 1470-nm radial fiber EVLA (EVLA-R group; n = 55 limbs), or 1470-nm jacket-tip fiber EVLA (EVLA-J group; n = 52 limbs). The patient demographics, CEAP clinical class, and intraoperative details were comparable among the three groups. The GSV occlusion rate at 1 year was 93% in the sRFA group, 93% in the EVLA-R group, and 95% in the EVLA-J group. No major complications were observed postoperatively. Endothermal heat-induced thrombosis was observed in 2 (4.4%), 1 (2.2%), and 2 (4.4%) patients in the sRFA, EVLA-R, and EVLA-J groups, respectively (P > .5). The VCSS showed greater improvement in the EVLA-R group at 1 week compared with that in the sRFA (P = .05) and EVLA-J (P = .002) groups. Changes in the CIVIQ-20 score were in favor of the EVLA-R group at 7 days (−14.3 ± 10.3 vs −7.9 ± 5.9; adjusted difference, 6.06; 95% confidence interval [CI], 1.57-10.55; P = .01) and 30 days (−12 ± 8 vs −11.2 ± 7; adjusted difference, 5.5; 95% CI, 1.21-9.81; P = .02) postoperatively compared with the sRFA group and at 7 days compared with the EVLA-J group (−14.3 ± 10.3 vs −9.6 ± 7.9; adjusted difference, −4.4; 95% CI, −9.06 to 0.22; P = .05). Analyzing the different components of the CIVIQ-20, pain, and physical scores showed a greater reduction in the EVLA-R group in the early postoperative period compared with that in the sRFA and EVLA-J groups. ConclusionsAll three EVTA modalities showed equal effectiveness and safety for the treatment of GSV reflux. EVLA with the 1470-nm radial fiber showed better outcomes in terms of early postoperative VCSSs and pain and physical CIVIQ scores. The clinical and quality of life benefits were similar for all modalities at 1 year postoperatively.

Monitoring Liver Stiffness Changes during Controlled Hyperthermia and Microwave Ablation Using Point Shear-Wave Elastography.

HomeRadiology: Imaging CancerVol. 1, No. 2 Previous Research HighlightsFree AccessMonitoring Liver Stiffness Changes during Controlled Hyperthermia and Microwave Ablation Using Point Shear-Wave ElastographyLuke WilkinsLuke WilkinsLuke WilkinsPublished Online:Nov 29 2019https://doi.org/10.1148/rycan.2019194013MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked InEmail Take-Away Points■ Major focus: To investigate the changes in liver stiffness following controlled hyperthermia and microwave ablation in an ex vivo bovine model using point shear-wave elastography.■ Key result: Point shear-wave elastography can provide an elasticity threshold predictive of coagulative necrosis development during microwave ablation in an ex vivo liver model.■ Impact: While there are current limitations, there are opportunities for incorporation of more advanced, real-time imaging techniques to more accurately predict zones of coagulative necrosis in tumor ablation.Noninvasive monitoring of thermal ablation can greatly decrease the risk of complications while ensuring treatment efficacy. While some thermal ablation systems have the capacity to provide real-time temperature feedback, it is typically restricted to the temperature at the device level and does not provide information on tissue temperature within the remainder of the treatment cavity. Crocetti et al explore the use of elastography as a potential method to provide real-time temperature monitoring.There are several US elastographic techniques. In point shear-wave elastography (pSWE), an acoustic radiation force is induced within the tissue. The disturbance created within the tissue moves through the tissue as a shear wave. By monitoring the corresponding tissue displacements created by the shear wave under B-mode imaging, inferences can be made regarding the stiffness of the underlying tissue. This is important for thermal ablation as it is well-known that coagulation (protein denaturation and tissue dehydration) occurs at 60°C. However, the effect of thermal-induced changes in the mechanical properties of the liver tissue has not yet been fully investigated. This article sought to investigate the changes in liver stiffness in controlled hyperthermia and microwave ablation (MWA) in an ex vivo animal model.The authors used five samples of ex vivo bovine liver that were uniformly heated to temperatures ranging from 40 to 100°C. B-mode US imaging and pSWE were then performed simultaneously. In addition, MWA was performed in 11 liver samples at 60 W. Shear wave velocity (SWV) was then measured in the regions of interest (ROIs) at 10–40 mm from the antenna. Histopathologic examination was performed to correlate mean values of SWV to treatment associated changes (within, border, or outside necrotic area). The article reports that a steep transition in liver stiffness was observed at 63.0°C ± 2.4. Through this first phase of experiments, the authors determined that the mean SWV at 60°C was 2.5 m/sec (defined as Avg60). For the next set of experiments, the threshold was defined as Avg60 + 0.5 m/sec or 3 m/sec. Eight of nine experiments showed that following stoppage of ablation when the predetermined ROI reached threshold SWV of 3 m/sec, the ROI was within the necrotic area at histologic examination. While this is notable, there was no correlation between SWV values for outside, border, and within necrosis. This markedly limits current clinical applicability of this technology. Future research may allow more accurate methods for detecting changes in tissue stiffness that would be able to predict tissue still outside the necrotic zone.Highlighted ArticleCrocetti L, Calcagni F, Gherarducci G, et al. Monitoring of thermal-induced changes in liver stiffness during controlled hyperthermia and microwave ablation in an ex vivo bovine model using point shear wave elastography. Cardiovasc Interv Radiol 2019;42(5):744–750. doi: https://doi.org/10.1007/s00270-018-02152-yHighlighted ArticleCrocetti L, Calcagni F, Gherarducci G, et al. Monitoring of thermal-induced changes in liver stiffness during controlled hyperthermia and microwave ablation in an ex vivo bovine model using point shear wave elastography. Cardiovasc Interv Radiol 2019;42(5):744–750. doi: https://doi.org/10.1007/s00270-018-02152-y Crossref, Medline, Google ScholarArticle HistoryPublished online: Nov 29 2019 FiguresReferencesRelatedDetailsCited ByRecommended Articles Elastography in Chronic Liver Disease: Modalities, Techniques, Limitations, and Future DirectionsRadioGraphics2016Volume: 36Issue: 7pp. 1987-2006US Elastography in Hepatic Fibrosis—Radiology In TrainingRadiology2021Volume: 299Issue: 2pp. 264-271Quantitative Elastography Methods in Liver Disease: Current Evidence and Future DirectionsRadiology2018Volume: 286Issue: 3pp. 738-763US Time-Harmonic Elastography: Detection of Liver Fibrosis in Adolescents with Extreme Obesity with Nonalcoholic Fatty Liver DiseaseRadiology2018Volume: 288Issue: 1pp. 99-106Update to the Society of Radiologists in Ultrasound Liver Elastography Consensus StatementRadiology2020Volume: 296Issue: 2pp. 263-274See More RSNA Education Exhibits Ultrasound Elastography Methods: Physical Principles, Techniques, and IndicationsDigital Posters2018Spleen Elastography and Portal Hypertension: An Overview and the Nitty-GrittiesDigital Posters2018Ultrasound Elastography in Children: How We Do it and What is it Helpful For?Digital Posters2019 RSNA Case Collection Hepatic AdenomatosisRSNA Case Collection2021 Cholecystitis and CholedocholithiasisRSNA Case Collection2020Radioembolization of Liver Metastasis RSNA Case Collection2020 Vol. 1, No. 2 Metrics Downloaded 178 times Altmetric Score PDF download

Design and Research of Thermal Ablation System Based on Dual-frequency Microwave Solid State Source

Microwave thermal ablation technology is widely used in the treatment of liver tumors because of its minimal invasiveness and small side effects. The precise control of the thermal dose largely determines the therapeutic effect of microwave thermal ablation. However, the current magnetron-based microwave thermal ablation device has the disadvantages of poor power output stability and high operating voltage. In view of the above problems, this paper selected the microwave solid-state source as the core device of microwave output, and designed a dual-frequency microwave thermal ablation system based on 2 450 MHz and 433 MHz. The system used the power detection circuit to perform PID feedback control on the actual output power of the system. The experimental results show that the maximum output power of the system is less than 1 W. The PID algorithm further enhances the accuracy and stability of the system output power while improving the system security. The dual-frequency microwave thermal ablation system designed in this paper can provide a safe and reliable experimental platform for subsequent research.

Comparison between microwave ablation and bipolar radiofrequency ablation in benign thyroid nodules: differences in energy transmission, duration of application and applied shots

Purpose: Comparison between different thermal ablation systems for thyroid nodules regarding their different procedural characteristics such as treatment-time, number of shots and energy transmission in the context of their clinical performance such as complication rate and volume reduction after three months.Methods: A total of 60 patients with 65 nodules underwent thermal ablation of thyroid nodules with either microwave ablation (MWA) (9 male, 15 female and mean age 57 ± 13 years) or radiofrequency ablation (RFA) (12 male, 24 female and mean age 54 ± 12 years).Results: Mean initial volume (MWA: 23.90 ± 17.35 ml; RFA: 29.44 ± 30.09 ml), energy transmission (MWA: 13.56 ± 10.17 kJ; RFA: 15.12 ± 13.45 kJ), energy transmission per ml (MWA: 0.85 ± 1.01 kJ/ml; RFA: 0.65 ± 0.32 kJ/ml), power (MWA: 22.69 ± 12.32 J/s; RFA: 20.97 ± 7.86 J/s) and duration of ablation (MWA: 618 ± 304 s; RFA: 695 ± 463 s) were not statistically different (p > .05). MWA required significantly less shots (MWA: 3 ± 1; RFA: 6 ± 3) than RFA (p < .05). At three-months follow-up a significant mean nodular volume reduction of 53.54 ± 15.40% after MWA and 51.21 ± 16.58% after RFA (p < .05) was measured. However, mean nodular volume reduction was not significantly different between both systems (p > .05). One patient treated by MWA reported a transient Horner’s syndrome, which recovered without any further treatment. Major complications such as nodule rupture, infection or persisting nerve injuries did not occur.Conclusion: Both systems are suitable to treat thyroid nodules and show no significant difference in the duration of application, energy transmission and volume reduction. However, MWA requires less shots to treat the whole nodule.

Development of a novel shock wave catheter ablation system-A validation study in pigs in vivo.

Although the radiofrequency catheter ablation (RFCA) is widely used for the treatment of tachyarrhythmias, it has three fundamental weaknesses as a thermal ablation system, including a limited lesion depth, myoendocardial injury linking to thromboembolism, and prolonged inflammation followed by subsequent recurrences. In order to overcome these limitations, we have been developing a shock wave (SW) catheter ablation (SWCA) system as a novel non-thermal therapy. In the present study, we validated our new SWCA system with increased SW intensity. In a total of 36 pigs, we applied our new SWCA to ventricular muscle in vivo for the following protocols. (i) Epicardial approach (n = 17): The lesion depth achieved by the SWCA from the epicardium was examined. High intensity SW achieved 5.2 ± 0.9 mm lesions (35 applications), where there was a strong correlation between SW intensity and lesion depth (R = 0.80, P < 0.001, 54 applications). (ii) Endocardial approach (n = 6): The extent of endocardial injury with the two energy sources was examined by electron microscopy (8 applications each). Shock wave catheter ablation markedly reduced myoendothelial injury compared with RFCA (4.3 ± 1.2 vs. 79.6 ± 4.8%, P < 0.01). The electrophysiological effects on the SW lesions were also confirmed using three-dimensional mapping system. (iii) Time-course study (n = 6 each): The healing process after ablation therapy was examined. We found transient inflammatory responses and accelerated reparative process with preserved blood flow in the SWCA group. These results indicate that our SWCA system is characterized, as compared with RFCA, by deeper lesion depth, markedly less myoendocardial injury and accelerated tissue repair process.

Image-guided thermal ablation with MR-based thermometry.

Thermal ablation techniques such as radiofrequency, microwave, high intensity focused ultrasound (HIFU) and laser have been used as minimally invasive strategies for the treatment of variety of cancers. MR thermometry methods are readily available for monitoring thermal distribution and deposition in real time, leading to decrease of incidents of normal tissue damage around targeted lesion. HIFU and laser-induced thermal therapy (LITT) are the two widely accepted tumor ablation techniques because of their compatibility with MR systems. MRI provides multiple temperature dependent parameters for thermal imaging, such as signal intensity, T1, T2, diffusion coefficient, magnetization transfer, proton resonance frequency shift (PRFS, including phase imaging and spectroscopy) as well as frequency shift of temperature sensitive contrast agents. Absolute temperature mapping techniques, including both spectroscopic imaging using metabolites as a reference and phase imaging using fat as a reference, are immune to susceptibility effects and are not dependent on phase differences. These techniques are intrinsically more reliable than relative temperature measurement by phase mapping methods. If the limitation of low temporal and spatial resolution could be overcome, these methods may be preferred for MR-guided thermal ablation systems. As of today, the most popular MR thermal imaging method applied in tumor thermal ablation surgery is, however, still PRFS based phase mapping technique, which only provides relative temperature change and is prone to motion artifacts.

Biomimetic Lipid-Based Nanosystems for Enhanced Dermal Delivery of Drugs and Bioactive Agents.

Clinical utility of conventional oral therapies is limited by their inability to deliver therapeutic molecules at the local or targeted site, causing a variety of side effects. Transdermal delivery has made a significant contribution in the management of skin diseases with enhanced therapeutic activities over the past two decades. In the modern era, various biomimetic and biocompatible polymer-lipid hybrid systems have been used to augment the transdermal delivery of therapeutics such as dermal patches, topical gels, iontophoresis, electroporation, sonophoresis, thermal ablation, microneedles, cavitational ultrasound, and nano or microlipid vesicular systems. Nevertheless, the stratum corneum still represents the main barrier to the delivery of vesicles into the skin. Lipid based formulations applied to the skin are at the center of attention and are anticipated to be increasingly functional as the skin offers many advantages for the direction of such systems. Accordingly, this review provides an overview of the development of conventional to advanced biomimetic lipid vesicles for skin delivery of a variety of therapeutics, with special emphasis on recent developments in this field including the development of transferosomes, niosomes, aquasomes, cubosomes, and other new generation lipoidal carriers.

Theranostic Radiopharmaceuticals Based on Gold Nanoparticles Labeled with (177)Lu and Conjugated to Peptides.

Gold nanoparticles (AuNPs) have been proposed for a variety of medical applications such as localized heat sources for cancer treatment and drug delivery systems. The conjugation of peptides to AuNPs produces stable multimeric systems with target-specific molecular recognition. Lutetium- 177 ((177)Lu) has been successfully used in peptide radionuclide therapy. Recently, (177)Lu-AuNPs conjugated to different peptides have been proposed as a new class of theranostic radiopharmaceuticals. These radioconjugates may function simultaneously as molecular imaging agents, radiotherapy systems and thermal-ablation systems. This article covers advancements in the design, synthesis, physicochemical characterization, molecular recognition assessment and preclinical therapeutic efficacy of gold nanoparticles radiolabeled with (177)Lu and conjugated to RGD (-Arg-Gly-Asp-), Lys(3)-Bombesin and Tat(49-57) peptides.

Magnetic resonance imaging-guided focal laser ablation for prostate cancer: A phase I trial.

e16128 Background: The majority of patients with low risk prostate cancer (CaP) harbor indolent disease and maybe safely observed on active surveillance (AS). However more than 30% of those on AS will ultimately receive definitive treatment. Focal therapy offers a treatment alternative that may provide oncologic control while avoiding treatment-related morbidity. The objective of this study was to determine the safety and feasibility of magnetic resonance (MR) image-guided focal laser ablation (FLA) of biopsy confirmed and MR visible prostate cancer. Methods: MR image-guided FLA was performed for men with Gleason < 7(3+4) when < 3 cores were positive in a standard 12 core biopsy corresponding to locations of MR lesions, or < 4 cores positive on MR image-guided biopsy. MR localization of biopsy-positive lesions were targeted via a transperineal approach and treated with a laser thermal ablation system. Validated quality of life questionnaires were completed pre-procedure and at each subsequent followup visit. MR-imaging was performed at 6 and 12 month followup with repeat fusion-guided biopsy perfomed at 12 months post-procedure. Results: 15 patients were treated with a mean preoperative PSA of 7.04 (Table 1). 14 patients had complete 1 year followup of which 6 patients had Gleason 6 and 8 patients had Gleason 6 disease. Mean operative time was 3.8 hours per treatment session for 1 lesion ablated. The mean (±Std Dev) IPSS and SHIM scores were 6.5±4.1 and 18.9±6.9 respectively, with no significant differences in SHIM or IPSS at 12 month followup. PSA was significantly lower at 1 year followup versus preoperatively (7.0 vs. 4.5, P = 0.0007).Five Grade 1 adverse events (AEs) were note in 4 patients, consisting of 4 incidences of hematuria and a pressure blister. Grade 2 AEs consisted of a UTI and epididymitis, one of which was unrelated to the procedure. Gleason 6 prostate cancer was identified in 2 prior treated lesions at repeat biopsy, of which 1 was observed and 1 underwent radical prostatectomy. Conclusions: MR-image guided FLA is safe and feasible for men with low risk CaP with acceptable oncologic outcomes at 1 year followup. Focal therapy is a promising alternate treatment that allows for preservation of functional outcomes. Clinical trial information: NCI-11-C-0158.

Dual applicator thermal ablation at 2.45 GHz: a numerical comparison and experiments on synchronous versus asynchronous and switched-mode feeding

Purpose: This paper compares the results obtained with numerical simulations and ex vivo experiments involving a dual applicator microwave thermal ablation system operating at a 2.45 GHz frequency, both in synchronous and asynchronous modes. Our purpose was to demonstrate that at this frequency an asynchronous or switched-mode system performs essentially as well as the synchronous one, in spite of the prevailing belief that coherence would assure better thermal (TH) synergy. Numerical analysis: The calculations of temperature fields were based on the Pennes bioheat equation, taking into account the effects of blood perfusion by means of a full-wave 3D simulator that allows numerical electromagnetic (EM) and TH analyses. Materials and methods: Experiments were done using a 100 W microwave (MW) power generator and a fast switched-mode sequential ‘active’ power splitter. By adding a further passive power splitter we arranged a test bed for an accurate experimental comparison of synchronous versus switched-mode TH ablations. Results: The experimental ablation zones produced by a dual applicator array on ex vivo swine tissue corresponded well with the simulated ones, confirming that the simplifications assumed in the full-wave analysis were compatible with the aim of our work. Conclusions: Numerical simulations and experiments show that at a 2.45 GHz industrial, scientific and medical (ISM) frequency, synchronous, asynchronous and switched-mode multi-probe systems are substantially equivalent in terms of ablative performance. Moreover, the switched-mode solution offers simpler operation along with lesser sensitivity to the placement of applicators in the tissue.

Randomized Controlled Trial Comparing the Efficacy of Impedance Control and Temperature Control of Radiofrequency Interstitial Thermal Ablation for Treating Small Hepatocellular Carcinoma

Objectives: A randomized controlled trial was conducted to evaluate the efficacy of impedance control of a radiofrequency interstitial thermal ablation system (RITA) used to treat hepatocellular carcinoma (HCC). Methods: Fifteen patients with hypervascular HCCs <20 mm in diameter were randomly treated with radiofrequency ablation (RFA) using conventional temperature control (group A) or impedance control methods (group B). RITA needle electrodes were used in all cases. We compared ablation time, extent of lesion ablation, and energy use between the two groups. Results: The median long and short diameters of the axial cross sections of radiofrequency-induced necrotic areas visualized by CT were 32 mm (range, 26-36) and 25 mm (20-31) in group A and 32 mm (28-40) and 31 mm (24-37) in group B, respectively. The short diameter of group B patients was significantly greater than that of group A patients (p = 0.029). The median ablation time was 18.8 min in group A and 13.4 min in group B, thus significantly shorter in group B (p = 0.001). The energy requirement did not differ significantly between the groups. Conclusions: Impedance control of the RITA system resulted in an increased size of the ablation zone and a decreased ablation time.

Role of percutaneous ultrasonographic guided radiofrequency ablation in the management of hepatocellular carcinoma

PurposeTo evaluate the effectiveness of percutaneous ultrasonographic guided radiofrequency thermal ablation in the management of hepatocellular carcinoma. Patients and methodsThis study included 100 patients presented with HCC showed 110 lesions, 91 lesions in the right lobe and 19 lesions in the left lobe. 86 were males (86%) and 14 were females (14%). All patients were subjected to laboratory investigations and imaging assessment including CT chest, bone scan, abdominal US and Triphasic Multislice Computed Tomography (MSCT) of the abdomen. The Radio Frequency Ablation (RFA) systems used were Radiofrequency Interstitial Thermal Ablation (RITA) System and RF 3000 monopolar system. ResultsGood ablation was achieved in 92 of 100 (92%) patients treated by RFA after the first session, incomplete necrosis found in 8 of 100 patients (8%). Local recurrence after RFA treatment occurred in 36 of 100 patients (36%). Local recurrence occurred after one month in one of 36 patients (2.8%), after 3months in 24 of 36 patients (66.7%), after 6months in 8 of 36 patients (22.2%), after 9months in 2 of 36 patients (5.5%) and after 12months in 1 of 36 patients (2.8%). At the end of the first year, the survival of the patients was (97%), at the end of the second year, the survival of the patients was (71.0%). ConclusionRadiofrequency thermal ablation is a simple, effective and less expensive technique with a low morbidity compared with surgical treatment. Radiofrequency thermal ablation can produce significant long-term survival rates and excellent local control for cirrhotic patients with early stage, unresectable HCC.

Multifunctional Radiolabeled Nanoparticles for Targeted Therapy

Nanoparticles can be near infrared (NIR)-fluorescent (e.g., gold nanoparticles, quantum dots or carbon nanotubes) or can have magnetic properties (e.g., iron oxide nanoparticles). These optical or magnetic properties can be exploited for use in thermal therapy and molecular imaging. Radiolabeled nanoparticles have proven to be promising tools in the diagnosis and therapy of malignant processes due to their multivalency and as multi-modal imaging agents. Furthermore, these radiopharmaceuticals may function simultaneously as both radiotherapy systems and thermal-ablation systems. This review examines the application of radiolabeled nanoparticles in the development of multifunctional nanosystems for targeted therapy.

Multifunctional targeted therapy system based on (99m) Tc/(177) Lu-labeled gold nanoparticles-Tat(49-57)-Lys(3) -bombesin internalized in nuclei of prostate cancer cells.

Radiolabeled gold nanoparticles may function simultaneously as radiotherapy and thermal ablation systems. The gastrin-releasing peptide receptor (GRP-r) is overexpressed in prostate cancer, and Lys(3) -bombesin is a peptide that binds with high affinity to the GRP-r. HIV Tat(49-57) is a cell-penetrating peptide that reaches the DNA. In cancer cells, (177) Lu shows efficient crossfire effect, whereas (99m) Tc that is internalized in the cancer cell nuclei acts as an effective system of targeted radiotherapy because of the biological Auger effect. The aim of this research was to evaluate the in vitro potential of (99m) Tc-labeled and (177) Lu-labeled gold nanoparticles conjugated to Tat(49-57)-Lys(3) -bombesin peptides ((99m) Tc/(177) Lu-AuNP-Tat-BN) as a plasmonic photothermal therapy and targeted radiotherapy system in PC3 prostate cancer cells. Peptides were conjugated to AuNPs (5 nm) by spontaneous reaction with the thiol group of cysteine (Cys). The effect on PC3 cell viability after laser heating of the AuNP-Tat-BN incubated with the cancer cells was conducted using an Nd:YAG laser pulsed for 5 ns at 532 nm (0.65 W/cm(2) ). For the (99m) Tc/(177) Lu-AuNP-Tat-BN to be obtained, the (177) Lu-DOTA-Gly-Gly-Cys and (99m) Tc-HYNIC-octreotide radiopeptides were first prepared and added simultaneously to a solution of AuNP-Tat-BN. (99m) Tc/(177) Lu-AuNP-Tat-BN (20 Bq/cell) was incubated with PC3 cells, and the effect on the cell proliferation was evaluated after 3 days. Fluorescence images of (99m) Tc/(177) Lu-AuNP-Tat-BN internalized in nuclei of PC3 were also obtained. After laser irradiation, the presence of AuNP-Tat-BN caused a significant increase in the temperature of the medium (46.4 vs 39.5 °C of that without AuNP) resulting in a significant decrease in PC3 cell viability down to 1.3%. After treatment with (99m) Tc/(177) Lu-AuNP-Tat-BN, the PC3 cell proliferation was inhibited. The nanosystem exhibited properties suitable for plasmonic photothermal therapy and targeted radiotherapy in the treatment of prostate cancer.

Effect of myoma size on failure of thermal balloon ablation or levonorgestrel releasing intrauterine system treatment in women with menorrhagia

ObjectiveThe aim of the present study was to identify variables associated with treatment failure in women with menorrhagia who were treated with thermal balloon ablation (TBA) or levonorgestrel releasing intrauterine system (LNG-IUS), and to determine if there are subgroups where one treatment type is more effective than the other.MethodsThe study included 106 women with menorrhagia who were treated with TBA or LNG-IUS at the study institute between January 2003 and December 2007, with a follow-up period greater than 12 months. Data were collected by retrospective review of medical records. Treatment failure was defined as persistent or recurrent menorrhagia within one year after treatment or hysterectomy at any time during follow-up. The relationships between variables and treatment outcome were analyzed using the chi-square or Fisher's exact test. The treatment outcome of TBA was compared with LNG-IUS.ResultsSixty-seven women were treated with TBA and 39 women were managed with LNG-IUS. Fifty-two women had a myoma ≥2.5 cm. Treatment failure was observed in 24 women (2 recurrent or persistent menorrhagia and 22 hysterectomies) and myoma size (≥2.5 cm vs. <2.5 cm) was associated with treatment outcome. TBA and LNG-IUS showed similar treatment outcomes.ConclusionA large myoma is a risk factor for treatment failure in women with menorrhagia treated with TBA or LNG-IUS.