Showing papers in "International Journal of Hyperthermia in 2017"
TL;DR: RFA and PLA are similarly feasible, safe and effective in treating benign thyroid nodules when performed by the same equipe and no difference in time course of the relative volume reduction between the two techniques was found.
Abstract: Purpose: To evaluate the reduction over time of benign thyroid nodules treated using percutaneous laser ablation (PLA) and radiofrequency ablation (RFA) by the same equipe.Materials and methods: Ninety patients (age 55.6 ± 14.1 years) underwent ablation for benign thyroid nodule causing compression/aesthetic dissatisfaction from 2011. Fifty-nine (age 55.8 ± 14.1 years) underwent RFA and 31 (age 55.2 ± 14.2 years) PLA, ultrasound guided. Technical success, complications, duration of ablation and treatment, energy deployed, volumetric percentage reduction at 1, 6 and 12 months were derived. A regression model for longitudinal measurements was used with random intercept and random slope. Values are expressed as mean ± standard deviation or N (%).Results: Technical success was always obtained. No major complications occurred. Mean ablation time was 30.1 ± 13.8 vs. 13.9 ± 5.9 min (p < .0001) and mean energy deployment was 5422.3 ± 2484.5 J vs. 34 662.7 ± 15 812.3 J in PLA vs. RFA group. Mean volume red...
116 citations
TL;DR: PMP is challenging, complex but nevertheless the most rewarding peritoneal malignancy amenable to cure by CRS and HIPEC.
Abstract: Pseudomyxoma peritonei (PMP) is an uncommon disease characterised by mucinous ascites, classically originating from a ruptured low grade mucinous neoplasm of the appendix. The natural history of PMP revolves around the "redistribution phenomenon", whereby mucinous tumour cells accumulate at specific sites with relative sparing of the motile small bowel and to a lesser extent other parts of the gastrointestinal tract. Peritoneal tumour accumulates due to gravity and at the sites of peritoneal fluid absorption, namely, the greater and lesser omentum and the under-surface of the diaphragm, particularly on the right. The optimal treatment is complete macroscopic tumour excision termed cytoreductive surgery (CRS) combined with Hyperthermic Intra-Peritoneal Chemotherapy (HIPEC). Total operating time for complete CRS and HIPEC for extensive PMP is around 10 h and generally involves bilateral parietal and diaphragmatic peritonectomies, right hemicolectomy, radical greater omentectomy with splenectomy, cholecystectomy and liver capsulectomy, a pelvic peritonectomy with, or without, rectosigmoid resection and bilateral salpingo-oophorectomy with hysterectomy in females. A unique feature of low grade PMP, which differs from other peritoneal malignancies, includes slow disease progression, which may be asymptomatic until advanced stages. Additionally, very extensive disease with a high "PCI" (Peritoneal Carcinomatosis Index) may still be amenable to complete excision and cure. In cases where complete tumour removal is not feasible, maximum tumour debulking can still result in long-term survival in PMP. PMP is challenging, complex but nevertheless the most rewarding peritoneal malignancy amenable to cure by CRS and HIPEC.
103 citations
TL;DR: Thermal ablation is increasingly being utilised in the treatment of primary and metastatic liver tumours, both as curative therapy and as a bridge to transplantation.
Abstract: Thermal ablation is increasingly being utilised in the treatment of primary and metastatic liver tumours, both as curative therapy and as a bridge to transplantation. Recent advances in high-powered microwave ablation systems have allowed physicians to realise the theoretical heating advantages of microwave energy compared to other ablation modalities. As a result there is a growing body of literature detailing the effects of microwave energy on tissue heating, as well as its effect on clinical outcomes. This article will discuss the relevant physics, review current clinical outcomes and then describe the current techniques used to optimise patient care when using microwave ablation systems.
96 citations
TL;DR: RFA was found to be safe for the treatment of benign thyroid nodules and recurrent thyroid cancers and on subgroup analysis, the overall and major complication rates were significantly higher for malignant thyroid nodule than for benign thyroid nodsules.
Abstract: Objective: We performed a systematic review and meta-analysis to evaluate the safety of radiofrequency ablation (RFA) for the treatment of benign thyroid nodules and recurrent thyroid cancersMaterials and methods: Ovid-MEDLINE, EMBASE, and Library of Cochrane databases were searched up to 12 July 2016 for studies on the safety of RFA for treating benign thyroid nodules or recurrent thyroid cancers Pooled proportions of overall and major complications were assessed using random-effects modelling Heterogeneity among studies was determined using the χ2 statistic for the pooled estimates and the inconsistency index I2Results: A total of 24 eligible studies were included, giving a sample size of 2421 patients and 2786 thyroid nodules 41 major complications and 48 minor complications of RFA were reported, giving a pooled proportion of 238% for overall RFA complications [95% confidence interval (CI): 142%–334%] and 135% for major RFA complications (95% CI: 089%–181%) There were no heterogenei
96 citations
TL;DR: The guidelines in this document focus on the clinical application and are complemented with a second, more technical quality assurance document providing instructions and procedure to determine essential parameters that describe heating properties of the applicator for superficial hyperthermia.
Abstract: Quality assurance guidelines are essential to provide uniform execution of clinical trials and treatment in the application of hyperthermia. This document provides definitions for a good hyperthermia treatment and identifies the clinical conditions where a certain hyperthermia system can or cannot adequately heat the tumour volume. It also provides brief description of the characteristics and performance of the current electromagnetic (radiative and capacitive), ultrasound and infra-red heating techniques. This information helps to select the appropriate heating technique for the specific tumour location and size, and appropriate settings of the water bolus and thermometry. Finally, requirements of staff training and documentation are provided. The guidelines in this document focus on the clinical application and are complemented with a second, more technical quality assurance document providing instructions and procedure to determine essential parameters that describe heating properties of the applicator for superficial hyperthermia. Both sets of guidelines were developed by the ESHO Technical Committee with participation of senior STM members and members of the Atzelsberg Circle.
91 citations
TL;DR: LA and RFA showed nearly similar outcome but LA was slightly more effective than RFA in large nodules and operator’s skills could be crucial in determining the extent of nodule volume reduction regardless of the used technique.
Abstract: Purpose: To compare technique efficacy and safety of laser ablation (LA) and radiofrequency ablation (RFA) in treatment of benign thyroid nodules.Materials and methods: Institutional review board approval was obtained, and patients’ consent was waived. 601 nodules were treated from May 2009 to December 2014 at eight centres, 449 (309 females, age 57 ± 14 years) with LA and 152 (107 females, age 57 ± 14 years) with RFA. A matched cohort composed of 138 patients from each group was selected after adjustment with propensity score matching. Factors influencing volume reduction at 6 and 12 months and complications were evaluated.Results: No significant differences were observed in the baseline characteristics between groups after propensity score matching adjustment. Mean nodule reduction at 6 and 12 months was −67 ± 19% vs. −57 ± 21% (p 30 mL had significantly higher percentage volume reducti...
84 citations
TL;DR: Vital volume increase tended to occur earlier than regrowth and might be an early sign of regrowth in following-up after the radiofrequency ablation of benign thyroid nodules.
Abstract: Objective: We evaluated long-term follow-up results of radiofrequency ablation of benign thyroid nodules to analyse the role of marginal vital tissue on nodule regrowth.Materials and methods: We reviewed the medical records of 54 patients who underwent radiofrequency ablation between June 2008 and November 2013 with pressure symptoms, and/or cosmetic problems. All patients were followed up at least 12 months on three occasions. To evaluate an early sign of regrowth, three types of nodule volumes (total volume, ablated volume and vital volume) were measured and calculated using ultrasonography. Regrowth was defined as a more than a 50% increase in the total volume and vital volume increase was defined as a more than 50% increase compared to the previously reported smallest volume on ultrasonography.Results: The mean follow-up period was 39.4 ± 21.7 (range, 13–87) months. Vital volume increases occurred in 31 nodules (57.4%) and there was regrowth in 13 nodules (24.1%). The mean timing of the vital ...
84 citations
TL;DR: A review of the recently obtained results as well as new unpublished data will be presented and discussed and possible developments of reliable, automatic and personalised treatment planning are discussed.
Abstract: Microwave thermal ablation (MTA) is a minimally invasive therapeutic technique aimed at destroying pathologic tissues through a very high temperature increase induced by the absorption of an electromagnetic field at microwave (MW) frequencies. Open problems, which are delaying MTA applications in clinical practice, are mainly linked to the extremely high temperatures, up to 120 °C, reached by the tissue close to the antenna applicator, as well as to the ability of foreseeing and controlling the shape and dimension of the thermally ablated area. Recent research was devoted to the characterisation of dielectric, thermal and physical properties of tissue looking at their changes with the increasing temperature, looking for possible developments of reliable, automatic and personalised treatment planning. In this paper, a review of the recently obtained results as well as new unpublished data will be presented and discussed.
79 citations
TL;DR: An advanced treatment planning software package for hyperthermia treatment planning for a wide variety of applications and the object-oriented structure of the source code allows relatively easy extension of the software package with additional tools when necessary when necessary.
Abstract: Background: Hyperthermia treatment planning using dedicated simulations of power and temperature distributions is very useful to assist in hyperthermia applications. This paper describes an advanced treatment planning software package for a wide variety of applications.Methods: The in-house developed C++ software package Plan2Heat runs on a Linux operating system. Modules are available to perform electric field and temperature calculations for many heating techniques. The package also contains optimisation routines, post-treatment evaluation tools and a sophisticated thermal model enabling to account for 3D vasculature based on an angiogram or generated artificially using a vessel generation algorithm. The use of the software is illustrated by a simulation of a locoregional hyperthermia treatment for a pancreatic cancer patient and a spherical tumour model heated by interstitial hyperthermia, with detailed 3D vasculature included.Results: The module-based set-up makes the software flexible and eas...
77 citations
TL;DR: Besides surgery and active surveillance, which are conflicting currently used management plans, RFA might represent an effective and a safe alternative for managing low-risk small PTCs, especially in patients ineligible for surgery.
Abstract: Purpose: The purpose of this study is to retrospectively evaluate the outcomes of radiofrequency ablation (RFA) of low-risk small papillary thyroid carcinomas (PTCs) in patients who were ineligible for surgery.Materials and methods: Between 2005 and 2009, six PTCs (mean diameter, 0.92 cm; range, 0.6–1.3 cm) in six patients were treated with RFA by three radiologists in two hospitals. The inclusion criteria for this study were (1) pathologically confirmed PTC without cytological aggressiveness, (2) single PTC without extrathyroidal extension, (3) no metastatic tumours and (4) ineligibility for surgery. RFA was performed using a radiofrequency generator and an 18-gauge internally cooled electrode. The medical records were reviewed and analysed, focussing on the procedural profiles of RFA, symptoms and complications during and after RFA, and changes in tumours on follow-up ultrasonography.Results: Before and after RFA, the results of thyroid function tests were normal in all patients. During 48.5 ± 1...
76 citations
TL;DR: CRS and HIPEC appear to be safe and effective in patients with peritoneal metastases from unusual cancer sites of origin, especially from rare ovarian carcinomas, PM from neuroendocrine tumours.
Abstract: Aim: The aim of this study was to assess the outcomes of patients operated on for peritoneal metastases from unusual cancer sites of origin, meaning apart from peritoneal metastases (PM) from colorectal, gastric and epithelial ovarian carcinomas, pseudomyxoma peritonei and mesothelioma.Patients and methods: A questionnaire concerning patients treated with cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) for PM arising from unusual cancer sites of origin was sent to all centres, which routinely performed HIPEC, through the Peritoneal Surface Oncology Group International and the RENAPE network.Results: Between September 1990 and June 2016, 850 procedures for unusual cases were performed in 781 patients, in 53 centres worldwide. Nearly two-thirds of the procedures were performed for three indications: rare ovarian carcinoma (n = 224), sarcoma (n = 189) and neuroendocrine tumours (n = 127). The median PCI was 12 [0–39]. Grade III–IV postoperative complications occurre...
TL;DR: The optimised non-invasive correction led to an average increase of 99% in the maximum pressure amplitude around the target and an average decrease in the distance between the peak pressure and the selected target, compared with uncorrected focusing.
Abstract: Transcranial brain therapy has recently emerged as a non-invasive strategy for the treatment of various neurological diseases, such as essential tremor or neurogenic pain. However, treatments require millimetre-scale accuracy. The use of high frequencies (typically ≥1 MHz) decreases the ultrasonic wavelength to the millimetre scale, thereby increasing the clinical accuracy and lowering the probability of cavitation, which improves the safety of the technique compared with the use of low-frequency devices that operate at 220 kHz. Nevertheless, the skull produces greater distortions of high-frequency waves relative to low-frequency waves. High-frequency waves require high-performance adaptive focusing techniques, based on modelling the wave propagation through the skull.This study sought to optimise the acoustical modelling of the skull based on computed tomography (CT) for a 1 MHz clinical brain therapy system.The best model tested in this article corresponded to a maximum speed of sound of 4000 m....
TL;DR: It is argued that hyperthermia – a therapeutic approach based on local heating of a tumour – is potentially beneficial for targeting cancer stem cells in solid tumours and may be a promising strategy to eliminate therapy-escaping and -resistant CSCs.
Abstract: Eradication of all malignant cells is the ultimate but challenging goal of anti-cancer treatment; most traditional clinically-available approaches fail because there are cells in a tumour that either escape therapy or become therapy-resistant. A subpopulation of cancer cells, the cancer stem cells (CSCs), is considered to be of particular significance for tumour initiation, progression and metastasis. CSCs are considered in particular to be therapy-resistant and may drive disease recurrence, which positions CSCs in the focus of anti-cancer research, but successful CSC-targeting therapies are limited. Here, we argue that hyperthermia - a therapeutic approach based on local heating of a tumour - is potentially beneficial for targeting CSCs in solid tumours. First, hyperthermia has been described to target cells in hypoxic and nutrient-deprived tumour areas where CSCs reside and ionising radiation and chemotherapy are least effective. Second, hyperthermia can modify factors that are essential for tumour survival and growth, such as the microenvironment, immune responses, vascularisation and oxygen supply. Third, hyperthermia targets multiple DNA repair pathways, which are generally upregulated in CSCs and protect them from DNA-damaging agents. Addition of hyperthermia to the therapeutic armamentarium of oncologists may thus be a promising strategy to eliminate therapy-escaping and -resistant CSCs.
TL;DR: Ex vivo data on bovine liver was more predictive of the actual clinical performance on liver malignancies than an in vivo porcine model, suggesting that outcomes are not only device-specific but must also be characterised on a tissue-by-tissue basis.
Abstract: Purpose: The aim of this study was to compare the performance of a microwave ablation (MWA) apparatus in preclinical and clinical settings.Materials and method: The same commercial 2.45 GHz MWA apparatus was used throughout this study. In total 108 ablations at powers ranging from 20 to 130 W and lasting from 3 to 30 min were obtained on ex vivo bovine liver; 28 ablations at 60 W, 80 W and 100 W lasting 5 and 10 min were then obtained in an in vivo swine model. Finally, 32 hepatocellular carcinomas (HCCs) and 19 liver metastases in 46 patients were treated percutaneously by administering 60 W for either 5 or 10 min. The treatment outcome was characterised in terms of maximum longitudinal and transversal axis of the induced ablation zone.Results: Ex vivo ablation volumes increased linearly with deposited energy (r2 = 0.97), with higher sphericity obtained at lower power for longer ablation times. Larger ablations were obtained on liver metastases compared to HCCs treated with 60 W for 10 min (p < 0...
TL;DR: Application of thermographically controlled wIRA-HT combined with extremely low-dose re-irradiation provides good local control throughout lifetime of heavily pre-treated breast cancer recurrences.
Abstract: Purpose: Evaluation of the efficacy and toxicity of a new setup of thermographically controlled water-filtered infra-red-A (wIRA) superficial hyperthermia (HT) combined with hypofractionated re-irradiation (re-RT) to treat large-sized breast cancer recurrences.Methods: Records of 73 heavily pre-irradiated patients with 103 treatment regions, treated from September 2009 to July 2015 were retrospectively analysed. Sixty-four patients with macroscopic disease were treated with 94 regions including 46 patients with lymphangiosis carcinomatosa. Hypofractionated RT consisted of 4 Gy once per week up to a total dose of 20 Gy delivered within 1–4 min after wIRA-HT. Heating of tumour nodules and diffusely spreading cancer lesions was performed under real-time thermographic temperature monitoring, maintaining the maximum skin temperature in the ROI between 42 °C and 43 °C, achieving intratumoural temperatures up to a depth of 2 cm between 39.5 °C and 42 °C. Seventeen patients received re-re-irradiation (re-...
TL;DR: The institution’s clinical experiences in the treatment of lung malignancies with MWA including patient selection, procedural technique, imaging follow-up, treatment outcomes and comparison of ablation techniques are reviewed.
Abstract: Approximately 30% of early stage lung cancer patients are not surgical candidates due to medical co-morbidities, poor cardiopulmonary function and advanced age. These patients are traditionally offered chemotherapy and radiation, which have shown relatively modest improvements in mortality. For over a decade, percutaneous image-guided ablation has emerged as a safe, cost-effective, minimally invasive treatment alternative for patients who would otherwise not qualify for surgery. Although radiofrequency ablation (RFA) is currently the most extensively studied and widely utilised technique in the treatment of lung malignancies, there is a growing body of evidence that microwave ablation (MWA) has several unique benefits over RFA and cryoablation in the lung. This article reviews our institution's clinical experiences in the treatment of lung malignancies with MWA including patient selection, procedural technique, imaging follow-up, treatment outcomes and comparison of ablation techniques.
TL;DR: Radiative heating yields more favourable SAR and temperature distributions for superficial tumours, compared with capacitive heating, especially within heterogeneous tissues, and higher tumour temperatures are achieved without occurrence of treatment limiting hot spots.
Abstract: Background: Superficial hyperthermia is applied in combination with radiotherapy for e.g. melanoma and recurrent breast cancer, using both capacitive and radiative systems. In this paper, numerical simulations are applied to address the question which technique yields the most favourable heating characteristics.Methods: A 434 MHz contact flexible microstrip applicator (CFMA type 4H, size 19.6 × 19.6 cm2) and a capacitive system consisting of two circular electrodes with diameter 15 and 25 cm were modelled. The water bolus of the CFMA was filled with deionised water and for capacitive heating both saline and deionised water were modelled. Specific absorption rate (SAR) and temperature simulations were performed for a perfused muscle-equivalent phantom and phantoms with a 1 cm thick superficial fat layer, assuming cylindrical target regions. Subsequently, a real patient model with a chest wall recurrence was studied with the target assumed to have muscle-like properties, fat properties or heterogene...
TL;DR: The US-guided MWA results in a satisfactory long-term outcome of the patients with a benign solitary thyroid nodule, and three risk factors for recurrence are identified: initial volume, vascularity and the energy per 1 ml reduction in nodular volume.
Abstract: Purpose: To determine the factors affecting the recurrence of the solitary benign thyroid nodules (BTN) after microwave ablation (MWA).Materials and methods: Between January 2013 and January 2015, a total of 110 patients with at least one solid thyroid nodule (solid component ≥ 80%) were enrolled. MWA was performed under continuous ultrasound (US) guidance. Before and during the follow-up, the thyroid nodule volume, thyroid function and cosmetic complaints were evaluated. Recurrence is defined by the new blood flow in the total ablation area or/and > 50% increase in nodule volume.Results: Almost all thyroid nodules were significantly decreased in size after MWA. After 12 months, the average volume of thyroid nodules was decreased from 12.6 ± 15.1 to 3.2 ± 5.7 ml. Of the total 110 patients, 16 cases had recurrence 12 months after MWA, and these patients had a larger initial volume than that of the non-recurrence patients (11.6 ± 14.9 vs. 23.9 ± 12.5, p < 0.01). The recurrence group also demonstrate...
TL;DR: A novel self-grounded Bow–Tie antenna design which is to serve as the basis element in a phased-array applicator to improve the heat delivery to deep seated tumours and indicates MR compatibility.
Abstract: Using UWB hyperthermia systems has the potential to improve the heat delivery to deep seated tumours. In this paper, we present a novel self-grounded Bow–Tie antenna design which is to serve as the basis element in a phased-array applicator. The UWB operation in the frequency range of 0.43–1 GHz is achieved by immersing the antenna in a water bolus. The radiation characteristics are improved by appropriate shaping the water bolus and by inclusion of dielectric layers on the top of the radiating arms of the antenna. In order to find the most appropriate design, we use a combination of performance indicators representing the most important attributes of the antenna. These are the UWB impedance matching, the transmission capability and the effective field size. The antenna was constructed and experimentally validated on muscle-like phantom. The measured reflection and transmission coefficients as well as radiation characteristics are in excellent agreement with the simulated results. MR image acquisitions with antenna located inside MR bore indicate a negligible distortion of the images by the antenna itself, which indicates MR compatibility.
TL;DR: The effect on haemoglobin saturation was higher in theCRet group than in the HP group, and the CRet intervention warmed deep tissue more effectively than HP intervention.
Abstract: Purpose: This study aims to evaluate the effects of Capacitive and Resistive electric transfer (CRet) and hotpack (HP) on haemoglobin saturation and tissue temperature.Materials and methods: The participants were 13 healthy males (mean age 24.5 ± 3.0). They underwent three interventions on different days: (1) CRet (CRet group), (2) HP (HP group) and (3) CRet without power (sham group). The intervention and measurement were applied at the lower paraspinal muscle. Indiba® active ProRecovery HCR902 was used in the CRet group, and the moist heat method was used in the HP group. Oxygenated, deoxygenated and total haemoglobin (oxy-Hb, deoxy-Hb, total-Hb) counts were measured before and after the 15-min interventions, together with the temperature at the skin surface, and at depths of 10 mm and 20 mm (ST, 10mmDT and 20mmDT, respectively). The haemoglobin saturation and tissue temperature were measured until 30 min after the intervention and were collected at 5-min intervals. Statistical analysis was perf...
TL;DR: The combination of CRS and intraperitoneal (IP) chemotherapy should now be considered standard of care for PSM from appendiceal epithelial cancers, colorectal cancer and peritoneal mesothelioma.
Abstract: Peritoneal surface malignancy (PSM) is a common manifestation of digestive and gynaecologic malignancies alike. At present, patients with isolated PSM are treated with a combination therapy of cytoreductive surgery (CRS) and hyperthermic peroperative intraperitoneal chemotherapy (HIPEC). The combination of CRS and intraperitoneal (IP) chemotherapy should now be considered standard of care for PSM from appendiceal epithelial cancers, colorectal cancer and peritoneal mesothelioma. Although there is a near universal standardisation regarding the CRS, we are still lacking a much-needed standardisation amongst the various IP chemotherapy treatment modalities used today in clinical practice. Pharmacologic evidence should be generated to answer important questions raised by the myriad of variables associated with IP chemotherapy.
TL;DR: The proposed model allows the prediction of the shrinkage of liver tissues upon microwave ablation given the extension of the carbonised and coagulated zones and may be useful in helping to predict whether sufficient tissue volume is ablated in clinical practice.
Abstract: Purpose: The aim of this study was to develop a predictive model of the shrinkage of liver tissues in microwave ablation.Methods: Thirty-seven cuboid specimens of ex vivo bovine liver of size ranging from 2 cm to 8 cm were heated exploiting different techniques: 1) using a microwave oven (2.45 GHz) operated at 420 W, 500 W and 700 W for 8 to 20 min, achieving complete carbonisation of the specimens, 2) using a radiofrequency ablation apparatus (450 kHz) operated at 70 W for a time ranging from 6 to 7.5 min obtaining white coagulation of the specimens, and 3) using a microwave (2.45 GHz) ablation apparatus operated at 60 W for 10 min. Measurements of specimen dimensions, carbonised and coagulated regions were performed using a ruler with an accuracy of 1 mm. Based on the results of the first two experiments a predictive model for the contraction of liver tissue from microwave ablation was constructed and compared to the result of the third experiment.Results: For carbonised tissue, a linear contrac...
TL;DR: The results show that the surrounding tissue environment significantly affects the ablation volume produced during RFA, and can play a critical role in minimising the damage to the surrounding healthy tissue and ensuring safe and risk free application of RFA.
Abstract: Purpose: This study aims to analyse the efficacy of temperature-controlled radiofrequency ablation (RFA) in different tissues.Materials and methods: A three-dimensional, 12 cm cubical model representing the healthy tissue has been studied in which spherical tumour of 2.5 cm has been embedded. Different body sites considered in the study are liver, kidney, lung and breast. The thermo-electric analysis has been performed to estimate the temperature distribution and ablation volume. A programmable temperature-controlled RFA has been employed by incorporating the closed-loop feedback PID controller. The model fidelity and integrity have been evaluated by comparing the numerical results with the experimental in vitro results obtained during RFA of polyacrylamide tissue-mimicking phantom gel.Results: The results revealed that significant variations persist among the input voltage requirements and the temperature distributions within different tissues of interest. The highest ablation volume has been pro...
TL;DR: Comparably sized ablation zones are achievable well above 1.9 GHz, despite increasingly localised power absorption, and specific absorption rate alone does not accurately predict ablation performance, particularly at higher frequencies where thermal diffusion plays an important role.
Abstract: Purpose: The use of higher frequencies in percutaneous microwave ablation (MWA) may offer compelling interstitial antenna design advantages over the 915 MHz and 2.45 GHz frequencies typically employed in current systems. To evaluate the impact of higher frequencies on ablation performance, we conducted a comprehensive computational and experimental study of microwave absorption and tissue heating as a function of frequency.Methods: We performed electromagnetic and thermal simulations of MWA in ex vivo and in vivo porcine muscle at discrete frequencies in the 1.9–26 GHz range. Ex vivo ablation experiments were performed in the 1.9–18 GHz range. We tracked the size of the ablation zone across frequency for constant input power and ablation duration. Further, we conducted simulations to investigate antenna feed line heating as a function of frequency, input power, and cable diameter.Results: As the frequency was increased from 1.9 to 26 GHz the resulting ablation zone dimensions decreased in the long...
TL;DR: Until data are available from evidence-based trials, it is reasonable to conclude that surgical cytoreduction and HIPEC is a rational and interesting, though still investigative, approach in the management of epithelial ovarian cancer, whose use should be employed within prospective clinical trials.
Abstract: The natural history of advanced-stage epithelial ovarian cancer is one of clinical remission after surgery and platinum/taxane-based intravenous (IV) and/or intraperitoneal (IP) chemotherapy followed by early or late recurrence in the majority of patients. Prevention of progression and recurrence remains a major hurdle in the management of ovarian cancer. Recently, many investigators have evaluated the use of normothermic and hyperthermic intraoperative IP drug delivery as a management strategy. This is a narrative review of the current status of clinical trials of hyperthermic intraoperative intraperitoneal chemotherapy (HIPEC) in ovarian cancer and the future directions for this treatment strategy. The existing studies on HIPEC in patients with epithelial ovarian cancer are mostly retrospective in nature, are heterogeneous with regards to combined inclusion of primary and recurrent disease and lack unbiased data. Until data are available from evidence-based trials, it is reasonable to conclude that surgical cytoreduction and HIPEC is a rational and interesting, though still investigative, approach in the management of epithelial ovarian cancer, whose use should be employed within prospective clinical trials.
TL;DR: Combination of transient data and steady state data makes it possible to simultaneously estimate tumour size, location and blood perfusion, and therefore its evaluation can possibly lead to the assessment of tumour malignancy.
Abstract: Purpose: We introduce a computational method to simultaneously estimate size, location and blood perfusion of the cancerous breast lesion from the surface temperature data.Methods: A 2D computational phantom of axisymmetric tumorous breast with six tissue layers, epidermis, papillary dermis, reticular dermis, fat, gland, muscle layer and spherical tumour was used to generate surface temperature distribution and thereby estimate tumour characteristics iteratively using an inverse algorithm based on Levenberg–Marquardt method. In addition to the steady state temperature data, we modified and expanded the inverse algorithm to include transient data that can be captured by dynamic infra-red imaging. Several test cases were considered for the transient analysis, where the depth, radii and blood perfusion of tumour were varied from 11 to 30 mm, 7 to 11 mm and 0.003 to 0.01 1/s, respectively.Results: Similar steady state temperature profile for different tumours makes it impossible to simultaneously esti...
TL;DR: The in vivo assessment of the effects of gold nanorod (AuNR)-mediated laser ablation (LA) of flank xenograft tumours represents the first step towards a rationally designed strategy to select the most promising laser settings and AuNRs concentration to improve solid tumour treatment outcomes.
Abstract: Purpose: The aim of the present study was the in vivo assessment of the effects of gold nanorod (AuNR)-mediated laser ablation (LA) of flank xenograft tumours. We investigated: the differences between intra-tumoural (TIT) and surface tumoural temperature (TS); the influence of AuNRs concentration and laser power (P) on both these temperatures and on tumour regression. Lastly, experimental data were used to validate a theoretical model developed to predict the effects of AuNR-mediated LA.Materials and methods: Thirty-two nude mice were treated using near-infra-red light at two P, 3 d after injecting increasing AuNR doses. TIT and TS were recorded during the procedure by two thermocouples, one located within the tumour and the other one on the skin adjacent to the tumour. Tumour regression was assessed 2 d after near-infra-red exposure via Xenogen imaging. A three-dimensional temperature map was obtained by finite element modelling.Results: TIT and TS difference is substantial when AuNRs are injecte...
TL;DR: The measured SAR may be used in simplified computer simulations to predict tissue temperature when the antenna geometry is unknown, suggesting inaccuracies in dielectric properties.
Abstract: Introduction: For computational models of microwave ablation (MWA), knowledge of the antenna design is necessary, but the proprietary design of clinical applicators is often unknown. We characterised the specific absorption rate (SAR) during MWA experimentally and compared to a multi-physics simulation.Methods: An infrared (IR) camera was used to measure SAR during MWA within a split ex vivo liver model. Perseon Medical’s short-tip (ST) or long-tip (LT) MWA antenna were placed on top of a tissue sample (n = 6), and microwave power (15 W) was applied for 6 min, while intermittently interrupting power. Tissue surface temperature was recorded via IR camera (3.3 fps, 320 × 240 resolution). SAR was calculated intermittently based on temperature slope before and after power interruption. Temperature and SAR data were compared to simulation results.Results: Experimentally measured SAR changed considerably once tissue temperatures exceeded 100 °C, contrary to simulation results. The ablation zone diameter...
TL;DR: There is a definite need to identify new pre-operative imaging parameters to define optimal indication of CRS with HIPEC.
Abstract: Background: During the Fifth International Workshop on Peritoneal Surface Malignancy in Milan in 2008, a consensus was reached that contrast-enhanced CT (ceCT) was the principal imaging modality for patients being evaluated for treatment of peritoneal metastases. This fact being accepted, the radiologic criteria for that may exclude patients from a high value cytoreductive surgery (CRS) plus hyperthermic perioperative chemotherapy (HIPEC) have not been reliably determined.Methods: From a consensus of surgeons and radiologists, radiologic images were selected and their determinant radiologic characteristics described. The anatomic pathology causing the abnormal images were identified and characterised. The cytoreductive surgical procedures that may, in selected patients, result in a complete resection of the pathology identified were presented.Results: Radiographs of 15 CT images that cause concern when a patient is being evaluated for CRS were listed. The anatomic pathology these images define and...
TL;DR: The combination of CRS and HIPEC is a promising integrated treatment strategy for GC PM that has encouraging initial results, calling for urgent further evaluation of this strategy in randomised control trials (RCTs).
Abstract: Purpose: There is no standard treatment for peritoneal metastases (PM) from gastric cancer (GC). The aim of this review is to evaluate the clinical trials on cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) for GC PM.Materials and methods: The published clinical trials on CRS + HIPEC for GC PM are critically evaluated, and survival and safety are the primary endpoints. In addition, the registered ongoing clinical trials are summarised.Results: The natural course of GC PM is <5 months. CRS + HIPEC could improve the overall survival (OS). In prospective studies, the median OS was 11.0 months in the CRS + HIPEC group vs. 5.4 months in the CRS alone group. In case-control studies, the median OS was 13.3 months in the CRS + HIPEC group vs. 7.9 months in the CRS alone group. In cohort studies, the median OS after CRS + HIPEC was 13.3. The median 1-, 2- and 5-year survival rates after CRS + HIPEC were 50.0%, 35.8% and 13.0%, respectively. There is no statistically signif...