Effect of thermal dose on heat shock protein expression after radio-frequency ablation with and without adjuvant nanoparticle chemotherapies

Purpose: The aim of this study was to evaluate the effect of different radio-frequency ablation (RFA) thermal doses on coagulation and heat shock protein (HSP) response with and without adjuvant nanotherapies.

Materials and methods: First, Fischer rats were assigned to nine different thermal doses of hepatic RFA (50–90?°C, 2–20?min, three per group) or no treatment (n?=?3). Next, five of these RF thermal doses were combined with liposomal-doxorubicin (Lipo-Dox, 1?mg intravenously) in R3230 breast tumours, or no tumour treatment (five per group). Finally, RFA/Lipo-Dox was given without and with an Hsp70 inhibitor, micellar quercetin (Mic-Qu, 0.3?mg intravenously) for two different RFA doses with similar coagulation but differing peri-ablational Hsp70 (RFA/Lipo-Dox at 70?°C × 5?min and 90?°C × 2?min, single tumours, five per group). All animals were sacrificed 24?h post-RFA and gross tissue coagulation and Hsp70 (maximum rim thickness and % cell positivity) were correlated to thermal dose including cumulative equivalent minutes at 43?°C (CEM₄₃).

Results: Incremental increases in thermal dose (CEM₄₃) correlated to increasing liver tissue coagulation (R² = 0.7), but not with peri-ablational Hsp70 expression (R² = 0.14). Similarly, increasing thermal dose correlated to increasing R3230 tumour coagulation for RF alone and RFA/Lipo-Dox (R² = 0.7 for both). The addition of Lipo-Dox better correlated to increasing Hsp70 expression compared to RFA alone (RFA: R² = 0.4, RFA/Lipo-Dox: R² = 0.7). Finally, addition of Mic-Qu to two thermal doses combined with Lipo-Dox resulted in greater tumour coagulation (p?<?0.0003) for RFA at 90?°C × 2?min (i.e. greater baseline Hsp70 expression) than an RFA dose that produced similar coagulation but less HSP expression (p?<?0.0004).

Conclusion: Adjuvant intravenous Lipo-Dox increases peri-ablational Hsp70 expression in a thermally dependent manner. Such expression can be exploited to produce greater tumour destruction when adding a second adjuvant nanodrug (Mic-Qu) to suppress peri-ablational HSP expression.     

Benign thyroid nodules treatment using percutaneous laser ablation (PLA) and radiofrequency ablation (RFA)

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?Conclusions: RFA and PLA are similarly feasible, safe and effective in treating benign thyroid nodules when performed by the same equipe. RFA is faster than PLA but require significantly higher energy.     

Preclinical evaluation of an MR-compatible microwave ablation system and comparison with a standard microwave ablation system in an ex vivo bovine liver model

Objective: Evaluation of a newly developed MR-compatible microwave ablation system with focus on ablation performance and comparison with a corresponding standard microwave ablation system.

Materials and methods: A total of 52 ablations were performed with a non-cooled microwave ablation system in an ex vivo bovine liver model using the following settings: [A] 16G-standard antenna, 2?cm active tip, 2.4?m cable; [B] MR-compatible 16G-antenna, 2?cm active tip, 2.4?m cable; [C] MR-compatible 16G-antenna, 2?cm active tip, extended 6?m cable; and [D] MR-compatible 16G-antenna, 4?cm active tip, extended 6?m cable. Ablation durations were 3, 5 and 10?min, and additionally 15?min for [D]. Ablations zones were measured for short-axis diameter (SA) and long-axis diameter (LA). Settings [A]–[C] were compared regarding SA, volume (V) and generator energy output (E) with analysis of variance and Tukey–Kramer post hoc test. Ablation performance of the MR-compatible settings [C] and [D] were compared regarding SA, V, E and sphericity index (SA/LA) with unpaired t-test. p?Results: No significant differences were found between [A], [B] and [C] regarding SA and V (10?min; SA[A]?=?25.8?±?2.4?mm, SA[B]?=?25.3?±?1.9?mm, SA[C]?=?25.0?±?2.0?mm, p?=?0.88; V[A]?=?17.8?±?4.4?cm³, V[B]?=?16.6?±?3.0?cm³, V[C]?=?17.8?±?2.7?cm³, p?=?0.85); however, the highest energy output was measured for setting [C] (10?min; [A]: 9.9?±?0.5?kJ, [B]: 10.1?±?0.5?kJ, [C]: 13.1?±?0.3?kJ, p?p?=?0.003; V[C]?=?17.8?±?2.7?cm³, V[D]?=?39.4?±?7.5?cm³, p?=?0.007; E[C]?=?13.1?±?0.3?kJ, E[D]?=?16.7?±?0.8?kJ, p?=?0.002) without significant difference in sphericity index (SA/LA[C]?=?0.46?±?0.02, SA/LA[D]?=?0.52?±?0.04, p?=?0.08).

Conclusion: The tested MR-compatible system can be used without loss of ablation performance compared to the standard system.     

Safety margin after radiofrequency ablation of hepatocellular carcinoma: precise assessment with a three-dimensional reconstruction technique using CT imaging

Purpose: To analyse the precise ablative margin (AM) after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) and the correlation between AM and local tumour progression (LTP) with a three-dimension (3D) reconstruction technique.

Methods: From March 2011 to May 2013, 134 patients who underwent RFA for 159 primary or recurrent HCCs within Milan criteria were enrolled. Contrast-enhanced computed tomography (CECT) scans were performed 1?week before and 1?month after treatment. The AM was measured in various directions using a 3D reconstruction technique that shows the index tumour and ablated zone on the same image. The average of all obtained AMs (average AM) and the smallest AM (min-AM) were calculated.

Results: The min-AM after RFA ranged from 1 to 9.3?mm (median?±?standard deviation, 4.8?±?1.8?mm). LTP was observed in 19 tumours from 19 patients. The median min-AM was 3.1?±?1.6?mm for patients with LTP, while the median min-AM of patients without LTP was 5.1?±?1.8?mm (p?=?0.023). After RFA, the 1-, 2- and 3-year LTP rates were 10.9, 25.9 and 35.1%, respectively, for patients with min-AM <5?mm, and 4.1, 4.1 and 4.1%, respectively, for patients with min-AM ≥5?mm (p?=?0.016). Multivariate analysis showed that only min-AM <5?mm was an independent risk factor for LTP after RFA (p?=?0.044, hazard ratio =4.587, 95% confidence interval, 1.045–22.296).

Conclusions: The 3D reconstruction technique is a precise method for evaluating the post-ablation margin. Patients with min-AM less than 5?mm had a higher probability of developing LTP.     

Minimally invasive local ablative therapies in combination with radioiodine therapy in benign thyroid disease: preparation,feasibility and efficiency – preliminary results

Abstract

Purpose: Initial studies of combinations of radioiodine therapy (RIT) and local ablative procedures for the treatment of thyroid nodules have shown promising results. The goal of this study was to evaluate the effectiveness of RIT combined with radiofrequency ablation (RFA) in patients with goitres and to determine which ablative procedure is the most suitable for a combined therapy.

Methods: Thirty patients with goitres were divided into two subgroups. A test group of 15 patients received combined therapy (RIT?+?RFA) and a control group of 15 patients received RIT mono therapy. All patients underwent assessments including ultrasound, laboratory evaluation (T3, T4, TSH, TG, TPOAb, TgAbTRAb) and scintigraphic imaging with Tc-99m-Pertechnetate. The 3-month volume reduction was used to evaluate therapy effectiveness.

Results: Combined therapy (subgroup 1) resulted in a significant (p?<?0.05) thyroid volume reduction (22.3?±?54?ml/32.2?±?58.2%) with better performance (p?>?0.05) than the control group (20.2?±?32.2?ml/29.6?±?42.1%). All patients became euthyroid after treatment. No major discomfort or complications occurred. A review of the literature investigating combinations of other local ablative procedures with RIT was performed to determine the most promising combination.

Conclusions: The present study confirms the positive experiences with the combined therapy of RIT and local ablative procedures shown in the current literature and approves this approach for the treatment of goitres with RFA?+?RIT. These findings, when confirmed by further studies, should expand the indication of combined therapy as a minimally invasive alternative to surgery.     

A comparison of laser with radiofrequency ablation for the treatment of benign thyroid nodules: a propensity score matching analysis

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?<?0.001)???70?±?19% vs. ?62?±?22% (p =?0.001) in LA group and in RFA group, respectively. Nodules with volume?>30?mL had significantly higher percentage volume reduction at 6 and 12?months (?69?±?19 vs. ?50?±?21, p?=?0.001) and (?73?±?18 vs. ?54?±?23 8, p?=?0.001) in the LA group than in the RFA group, respectively. In both groups, operator’s skills affected the results. Major complications occurred in 4 cases in each group (p?=?0.116)

Conclusions: LA and RFA showed nearly similar outcome but LA was slightly more effective than RFA in large nodules. Operator’s skills could be crucial in determining the extent of nodule volume reduction regardless of the used technique.     

Radiofrequency ablation combined with liposomal quercetin to increase tumour destruction by modulation of heat shock protein production in a small animal model

Purpose: To investigate the effect of heat shock protein (HSP) modulation on tumour coagulation by combining radiofrequency (RF) ablation with adjuvant liposomal quercetin and/or doxorubicin in a rat tumour model.

Methods: Sixty R3230 breast adenocarcinoma tumours/animals were used in this IACUC-approved study. Initially, 60 tumours (n?=?6, each subgroup) were randomised into five groups: (1) RF alone, (2) intravenous (IV) liposomal quercetin alone (1?mg/kg), (3) IV liposomal quercetin followed 24?h later with RF, (4) RF followed 15?min later by IV liposomal doxorubicin (8?mg/kg), (5) IV liposomal quercetin 24?h before RF followed by IV liposomal doxorubicin 15?min post-ablation. Animals were sacrificed 4 or 24?h post-treatment and gross coagulation diameters were compared. Next, immunohistochemistry staining was performed for Hsp70 and cleaved caspase-3 expression. Comparisons were performed by using Student t-tests or ANOVA.

Results: Combination RF-quercetin significantly increased coagulation size compared with either RF or liposomal quercetin alone (13.1?±?0.7?mm vs. 8.8?±?1.2?mm or 2.3?±?1.3?mm, respectively, P?<?0.001 for all comparisons). Triple therapy (quercetin-RF-doxorubicin) showed larger coagulation diameter (14.5?±?1.0?mm) at 24?h than quercetin-RF (P?=?0.016) or RF-doxorubicin (13.2?±?1.3?mm, P?=?0.042). Combination quercetin-RF decreased Hsp70 expression compared with RF alone at both 4?h (percentage of stained cells/hpf 22.4?±?13.9% vs. 38.8?±?16.1%, P?<?0.03) and 24?h (45.2?±?10.5% vs. 81.1?±?3.6%, P?<?0.001). Quercetin-RF increased cleaved caspase-3 expression at both 4?h (percentage of stained cells/hpf 50.7?±?13.4% vs. 41.9?±?15.1%, P?<?0.03) and 24?h (37.4?±?7.8% vs. 33.2?±?6.5%, P?=?0.045); with, triple therapy (quercetin-RF-doxorubicin) resulting in the highest levels of apoptosis (45.1?±?10.7%) at 24?h. Similar trends were observed for rim thickness.

Conclusions: Suppression of HSP production using adjuvant liposomal quercetin can increase apoptosis and improve RF ablation-induced tumour destruction. Further increases in tumour coagulation can be seen including an additional anti-tumour adjuvant agent such as liposomal doxorubicin.     

RF ablation with adjuvant therapy: Comparison of external beam radiation and liposomal doxorubicin on ablation efficacy in an animal tumor model

Purpose: To determine the critical thermal dosimetry and relative efficacy for RF ablation combined with external beam radiation (XRT) or liposomal doxorubicin (LD), in an animal tumor model.

Materials and methods: This study was performed in two phases, in 13–18 mm diameter R3230 tumors subcutaneously implanted into Fischer rats. In phase 1, tumors (n = 30) were randomized into six groups. RF energy (titrated to 70°C tip temperature) was applied for either 2.5 or 5 min (n = 15, each group). For each duration, one of three adjuvant therapies was applied (n = 5, each): no therapy (control), LD (1 mg intravenously, 30 min post-RF), or XRT (20 Gy at 1 Gy min^?1, within 2 h post-RF), with sacrifice at 48 h for pathologic analysis. In phase 2, thermal mapping was performed in 20 tumors throughout RF application (70°C; 5 min), at 1.5–7 mm distances from the active electrode tip. Temperature profiles throughout the tumor were constructed and were used to interpolate temperatures over time at the critical ablation margin, to derive maximum threshold temperature, AUC (area under the curve) and CEM₄₃ (cumulative equivalent minutes at 43°C). Ablation sizes and all calculated values were compared within and across experimental groups using MANOVA statistics with pair-wise T-test for individual comparisons.

Results: RF/XRT produced the largest coagulation (11.7 ± 1.5 mm at 2.5 min, ≥15 ± 0.7 mm at 5 min), followed by RF/LD, and then RF alone (p < 0.001 for all comparisons). RF/XRT demonstrated temperature threshold decreases from RF alone of 11.7 ± 0.01°C and 12.7 ± 0.38°C at 2.5 and 5 min respectively (with absolute thresholds of 42°C for XRT compared to 52°C for RF alone). RF/LD had decreases of 4.0°C at 2.5 min and 4.4°C at 5 min. Thermal dose requirements (AUC) decreased by 7.79% or 9.28% for RF/LD compared to ≥19.36% or 25.82% for RF/XRT at 2.5 and 5 min (p < 0.001). CEM₄₃ values followed similar patterns (p < 0.001), but with a reduction of 10¹ and 10⁴ in magnitude for RF/LD and RF/XRT therapies at 5 min, respectively.

Conclusions: For a standardized RF dose, the combination of high dose XRT and RF increased ablation size compared to RF and liposomal doxorubicin or RF alone. Increased ablation size is more closely associated with decreased temperature threshold necessary to induce coagulation, rather than the total thermal dose.     

Pathological effects of lung radiofrequency ablation that contribute to pneumothorax,using a porcine model

Objectives: The incidence of pneumothorax is 7 times higher after lung radiofrequency ablation (RFA) than after lung biopsy. The reasons for such a difference have never been objectified. The histopathologic changes in lung tissue are well-studied and established for RF in the ablation zone. However, it has not been previously described what the nature of thermal injury might be along the shaft of the RF electrode as it traverses through normal lung tissue to reach the ablation zone. The purpose of this study was to determine the changes occurring around the RF needle along the pathway between the ablated zone and the pleura.

Material and methods: In 3 anaesthetised and ventilated swine, 6 RFA procedures (right and left lungs) were performed using a 14-gauge unipolar multi-tined retractable 3?cm radiofrequency LeVeen probe with a coaxial introducer positioned under CT fluoroscopic guidance. In compliance with literature guidelines, we implemented a gradually increasing thermo-ablation protocol using a RF generator. Helical CT images were acquired pre- and post-RFA procedure to detect and evaluate pneumothorax. Four percutaneous 19-gauge lung biopsies were also performed on the fourth swine under CT guidance. Swine were sacrificed for lung ex vivo examinations, scanning electron microscopy (SEM) and pathological analysis.

Results: Three severe (over 50?ml) pneumothorax were detected after RFA. In each one of them, pathological examination revealed a fistulous tract between ablation zone and pleura. No fistulous tract was observed after biopsies.

In the 3 cases of severe pneumothorax, the tract was wide open and clearly visible on post procedure CT images and SEM examinations. The RFA tract differed from the needle biopsy tract. The histological changes that are usually found in the ablated zone were observed in the RFA tract’s wall and were related to thermal lesions. These modifications caused the creation of a coagulated pulmonary parenchyma rim between the thermo-ablation zone and the pleural space. The structural properties of the damage can explain why the RFA tract is remains patent after needle withdrawal.

Conclusion: Our study demonstrates for the first time that the changes around the RF needle are the same as in the ablated zone. The damage could create fistulous tracts along the needle path between thermo-ablation zone and pleural space. These fistulas could certainly be responsible for severe pneumothorax that occurs in many patients treated with lung RFA.     

Characterization of the RF ablation-induced ‘oven effect’: The importance of background tissue thermal conductivity on tissue heating

Purpose: To determine the effect of background tissue thermal conductivity on RF ablation heating using ex vivo agar phantoms and computer modelling.

Method: Two-compartment cylindrical agar phantom models (5% agar, 5% NaCl, 3% sucrose) were constructed. These included a standardized inner compartment (2?cm diameter, 4?cm length, 0.25% agar) representing a tumour, surrounded by an outer compartment representing background tissue. The thermal conductivity of the outer compartment was varied from 0.48?W?m^?1°C (normal liver) to 0.23?W?m^?1°C (fat) by adding a fat-saturated oil-based solute (10–90%) to the agar. RF ablation was applied at 2000?mA current for 2?min. Temperatures were recorded up to 4?cm from the electrode tip at 1?cm intervals. Subsequently, a 2-D finite element computer model was used to simulate RF ablation of 2–24?min duration for tumours measuring 2–4?cm in diameter surrounded by tissues of different thermal conductivity with the presence or absence of perfusion (0–5?kg?m^?3?s^?1) (n?=?44). A comparison of results was performed.

Results: In agar phantoms, the amount of fat in the background tissue correlated with thermal conductivity as a negative exponential function (r²?=?0.98). Significantly increased temperatures were observed at the edge of the inner compartment (1?cm from the electrode tip) as the fat content of the outer compartment increased (p?<?0.01). Thus, temperatures at 2?min measured 31.5?±?2.2°C vs 45.1?±?3.1°C for thermal conductivities of 0.46?W?m^?1°C (10% fat) and 0.23?W?m^?1°C (90% fat), respectively. On the other hand, higher levels of fat led to lower temperature increases in the background compartment (0.2?±?0.3°C for 90% fat vs. 1.1?±?0.05°C for 10% fat, p?<?0.05). Phantom thermal heating patterns correlated extremely well with computer modelling (r²?=?0.93), demonstrating that background tissues with low thermal conductivity increase heating within the central tumour, particularly for longer durations of RF ablation and in smaller tumours. Furthermore, computer modelling demonstrated that increases in temperature at the tumour margin for background tissues of lower thermal conductivity persisted in the presence of perfusion, with a clinically relevant 4.5°C difference between background thermal conductivities of fat and soft tissue for a 3?cm tumour with perfusion of 2?kg?m^?3?s^?1, treated for 12?min.

Conclusion: Lower thermal conductivity of background tissues significantly increases temperatures within a defined ablation target. These findings provide insight into the ‘oven effect’ (i.e. increased heating efficacy for tumours surrounded by cirrhotic liver or fat) and highlight the importance of both the tumour and the surrounding tissue characteristics when contemplating RF ablation efficacy.     

Clinical application of hepatic wedge ablation for treating liver malignancies of the inferior margin: a new ablation technique

Purpose: To determine the efficacy and safety of percutaneous hepatic wedge ablation in treating hepatic malignancies of the inferior margin.

Materials and methods: Seventy-seven patients with hepatic malignancies at the inferior margin underwent percutaneous radiofrequency ablation (RFA). Thirty-two patients underwent hepatic wedge ablation and 45 patients underwent conventional tumour ablation. Comparative analysis of the two groups was performed including gender, age, tumour size, number of ablation cycles, ablation duration and injected hydrodissection volume. The rate of technical success, local tumour progression, intrahepatic distant recurrence, major complications and overall survival were assessed and compared. Survival analysis was analysed using the Kaplan–Meier method. Differences in the survival rates were compared with log-rank test.

Results: The mean number of ablation cycles and ablation duration were significantly higher in the hepatic wedge ablation group than conventional tumour ablation (1.6?±?0.9 vs. 1.2?±?0.4, p?=?.042, and 30.2?±?18.5 vs. 22.5?±?8.5?min, p?=?.031, respectively). The local tumour progression rate was significantly lower in hepatic wedge ablation group (0% vs. 17.78%, p?=?.038) at median follow-up of 21 months. The rate of technical success, intrahepatic distant recurrence, major complications and overall survival did not differ between the two groups.

Conclusion: Hepatic wedge ablation appears to be a highly effective treatment for hepatic malignancies in the inferior margin and provides a better local control than conventional tumour ablation.     

Technical aspects of osteoid osteoma ablation in children using MR-guided high intensity focussed ultrasound

Background: Osteoid osteoma (OO) is a painful bone tumour occurring in children and young adults. Magnetic resonance imaging-guided high intensity focussed ultrasound (MR-HIFU) allows non-invasive treatment without ionising radiation exposure, in contrast to the current standard of care treatment with radiofrequency ablation (RFA). This report describes technical aspects of MR-HIFU ablation in the first 8 paediatric OO patients treated in a safety and feasibility clinical trial (total enrolment of up to 12 patients).

Materials and methods: OO lesions and adjacent periosteum were treated with MR-HIFU ablation in 5–20 sonications (sonication duration?=?16–48?s, frequency?=?1.2?MHz, acoustic power?=?20–160?W). Detailed treatment workflow, patient positioning and coupling strategies, as well as temperature and tissue perfusion changes were summarised and correlated.

Results: MR-HIFU ablation was feasible in all eight cases. Ultrasound standoff pads were shaped to conform to extremity contours providing acoustic coupling and aided patient positioning. The energy delivered was 10?±?7?kJ per treatment, raising maximum temperature to 83?±?3?°C. Post ablation contrast-enhanced MRI showed ablated volumes ranging 0.46–19.4?cm³ extending further into bone (7?±?4?mm) than into soft tissue (4?±?6?mm, p?=?0.01, Mann–Whitney). Treatment time ranged 30–86?min for sonication and 160?±?40?min for anaesthesia. No serious treatment-related adverse events were observed. Complete pain relief with no medication occurred in 7/8 patients within 28 days following treatment.

Conclusions: MR-HIFU ablation of painful OO appears technically feasible in children and it may become a non-invasive and radiation-free alternative for painful OO. Therapy success, efficiency, and applicability may be improved through specialised equipment designed more specifically for extremity bone ablation.     

Radiofrequency hyperthermia-enhanced herpes simplex virus-thymidine kinase/ganciclovir direct intratumoral gene therapy of hepatocellular carcinoma

Purpose: To determine the feasibility of using radiofrequency hyperthermia (RFH) and to enhance the therapeutic effect of herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) for the treatment of hepatocellular carcinoma (HCC).

Materials and methods: Human HCC cells (HepG2) were first transfected with lentivirus/luciferase. For both in vitro confirmation and in vivo validation, luciferase-labeled HCC cells and HCC tumour xenografts on mice received different treatments: (i) combination therapy of intratumoral HSV-TK/GCV-mediated gene therapy plus magnetic resonance imaging heating guidewire (MRIHG)-mediated RFH; (ii) gene therapy only; (iii) RFH only; and (iv) phosphate-buffered saline (PBS) as control. Cell proliferation was quantified. Tumour changes were monitored by ultrasound imaging and bioluminescence optical imaging before and at days 7 and 14 after treatments, which were correlated with subsequent histology.

Results: In vitro, the lowest cell proliferation was seen in the combination therapy group compared with control groups (29?±?6% vs. 56?±?9%, 93?±?4%, and 100?±?5%, p?p?p?Conclusion: RFH can enhance HSV-TK/GCV-mediated gene therapy of HepG2 cell line and mice human HCC xenografts, which may open new avenues for effective management of HCC using MR/RFH integrated interventional gene therapy.     

Cardiac and respiratory effects of deep regional hyperthermia using an 8 MHz radiofrequency-capacitive device on patients with cancer

Purpose: Hyperthermia (HT), an adjuvant therapy for variable cancers, may cause physiological changes in the patients, which may lead to cardiovascular problems. Among various HT treatments, the physiological effects of deep regional HT are still unclear. We examined the physiological alterations throughout deep regional HT to improve the HT safety.

Materials and methods: Thirty-one patients (age: 61?±?12 years) with cancer received HT in the thoracic or upper abdominal regions using an 8-MHz radiofrequency-capacitive-device for 50?min. Rectal temperature (T_rec), systolic and diastolic blood pressures (SBP and DBP), pulse rate (PR), respiratory rate (RR), percutaneous oxygen saturation (SpO₂) and sweating volume were evaluated throughout HT.

Results: At 50?min after starting HT, T_rec, PR and RR were significantly increased compared with the baseline values (T_rec: 38.2?±?1.4 vs. 36.3?±?0.8?°C, p?p?p?p?p?2 on average.

Conclusions: Deep regional HT increased the deep body temperature and resulted in an increase of sweating with peripheral vasodilatation. Consequently, a significant reduction in BP would be induced on standing after HT. Careful attention is needed for patients receiving HT, especially when standing after HT.     

HSP27 phosphorylation increases after 45°C or 41°C heat shocks but not after non-thermal TDMA or GSM exposures

Purpose: Experiments with cultured HeLa, S3 and E.A. Hy296 cells were performed to determine if exposure to acute (30?min at 45°C) or chronic (2?h at 41°C) heat shocks or to non-thermal exposures of radiofrequency radiation (RF) induce changes in HSP27 phosphorylation.

Materials and methods: The radiofrequency (RF) exposures used in this study were 847?MHz time division multiple access modulated (TDMA) at a specific absorption rate (SAR) of 5?W?kg^?1 for 1, 2 or 24?h or 900?MHz GSM modulated (GSM) at a SAR of 3.7?W?kg^?1 for 1, 2 or 5?h. HSP27 phosphorylation was evaluated by resolving the various phosphorylation forms using two-dimensional gel electrophoresis measuring the relative amount of each by densitometry. Alternatively, an antibody specific for phosphorylated HSP27 was used to detect changes in HSP27 phosphorylation levels. All heat shock and RF exposure conditions were analysed simultaneously along with a matched incubator control sample. Each experiment was repeated three times.

Results: Following heat shock, the degree of phosphorylation of HSP27 varied with the heat dose, with acute hyperthermia (45°C) having an increased proportion of higher phosphorylated forms. Exposure of HeLa S3 cells to 5?W?kg^?1 TDMA for 1, 2 or 24?h did not induce significant differences in the levels of HSP27 phosphorylation compared to incubator control or sham. Exposure of E.A. Hy926 cells to 3.7?W?kg^?1 900?MHz GSM for 1, 2 or 5?h did not induce significant differences in the levels of HSP27 phosphorylation compared to sham exposed.

Conclusions: Acute and moderate hyperthermia significantly increase HSP27 phosphorylation, but there was no significant change in the levels of HSP27 following non-thermal exposure to TDMA and GSM modulated RF radiations.     

Conductive interstitial thermal therapy device for surgical margin ablation: In vivo verification of a theoretical model

Purpose: To demonstrate the efficacy and predictability of a new conductive interstitial thermal therapy (CITT) device to ablate surgical margins.

Method: The temperature distributions during thermal ablation of CITT were calculated with finite element modelling in a geometrical representation of perfused tissue. The depth of ablation was derived using the Arrhenius and the Sapareto and Dewey (S&D) models for the temperature range of 90 to 150°C. The female pig animal model was used to test the validity of the mathematical model. Breast tissues were ablated to temperatures in the range of 79–170°C, in vivo. Triphenyltetrazolium chloride viability stain was used to delineate viable tissue from ablated regions and the ablation depths were measured using digital imaging.

Results: The calculations suggest that the CITT can be used to ablate perfused tissues to a 10–15?mm width within 20 minutes. The measured and calculated depths of ablation were statistically equivalent (99% confidence intervals) within?±?1mm at 170°C. At lower temperatures the equivalence between the model and the observations was within?±?2?mm.

Conclusion: The CITT device can reliably and uniformly ablate a 10–15?mm wide region of soft tissue. Thus, it can be used to secure negative margins following the resection of a primary tumor, which could impede local recurrences in the treatment of local diseases such as early staged, non-metastatic, breast cancer.     

Enhancing the abscopal effect of radiation and immune checkpoint inhibitor therapies with magnetic nanoparticle hyperthermia in a model of metastatic breast cancer

Abstract

Purpose: Enhancing immune responses in triple negative breast cancers (TNBCs) remains a challenge. Our study aimed to determine whether magnetic iron oxide nanoparticle (MION) hyperthermia (HT) can enhance abscopal effects with radiotherapy (RT) and immune checkpoint inhibitors (IT) in a metastatic TNBC model.

Methods: One week after implanting 4T1-luc cells into the mammary glands of BALB/c mice, tumors were treated with RT (3?×?8?Gy)±local HT, mild (HT_M, 43?°C/20?min) or partially ablative (HT_Abl, 45?°C/5?min plus 43?°C/15?min),±IT with anti-PD-1 and anti-CTLA-4 antibodies (both 4?×?10?mg/kg, i.p.). Tumor growth was measured daily. Two weeks after treatment, lungs and livers were harvested for histopathology evaluation of metastases.

Results: Compared to untreated controls, all treatment groups demonstrated a decreased tumor volume; however, when compared against surgical resection, only RT?+?HT_M+IT, RT?+?HT_Abl+IT and RT?+?HT_Abl had similar or smaller tumors. These cohorts showed more infiltration of CD3⁺ T-lymphocytes into the primary tumor. Tumor growth effects were partially reversed with T-cell depletion. Combinations that proved most effective for primary tumors generated modest reductions in numbers of lung metastases. Conversely, numbers of lung metastases showed potential to increase following HT?+?IT treatment, particularly when compared to RT. Compared to untreated controls, there was no improvement in survival with any treatment.

Conclusions: Single-fraction MION HT added to RT?+?IT improved local tumor control and recruitment of CD3⁺ T-lymphocytes, with only a modest effect to reduce lung metastases and no improvement in overall survival. HT?+?IT showed potential to increase metastatic dissemination to lungs.     

Percutaneous microwave ablation (MWA) increased the serum levels of VEGF and MMP-9 in Stage I non-small cell lung cancer (NSCLC)

Background: Lung cancer is the leading cause of cancer death around the world. Percutaneous microwave ablation (MWA) is an emerging treatment strategy for medically inoperable early-stage non-small cell lung cancer (NSCLC). In this study, we investigated the association of MWA and serum angiogensis promoters VEGF and MMP-9 in these patients subgroup.

Methods: We enrolled 52 patients with Stage I NSCLC patients in this study. For each patient, blood samples were drawn by venous puncture, one immediately prior to MWA and the others on Post-Procedure Days (PPD) 1, 3, 5, 7, 10 and 14. Serum samples were analysed for VEGF and MMP-9 levels with use of commercially available enzyme-linked immunosorbent assay. Also, blood samples of 28 healthy volunteers were set as the healthy controls.

Results: We did not observe a significant difference of serum VEGF and MMP-9 between NSCLC patients and healthy controls. The VEGF levels increased on the first day (256.0?±?6.16?pg/ml, p?p?p?p?p?p?>?0.05). The highest MMP-9 level was observed on PPD5 (399.7?±?17.70?ng/ml, p?Conclusion: Our preliminary results indicated that percutaneous MWA resulted in increased serum levels of VEGF and MMP-9 in Stage I NSCLC patients. Antiangiogenesis approaches may be helpful for patients defending against metastases during the immediate post-ablation time window.     

Sequential activation of multiple grounding pads reduces skin heating during radiofrequency tumor ablation

Purpose: Radiofrequency (RF) tumor ablation has become an accepted treatment modality for tumors not amenable to surgery. Skin burns due to ground pad heating may become a limiting factor for further increase in ablation zone dimensions and generator power. We investigated a method were groups of ground pads are sequentially activated to reduce skin heating.

Methods: We compared conventional operation (i.e. simultaneous connection of all pads) to sequentially switched activation of the pads where different pad combinations are active for periods of ～0.3 - 8 s. The timing during sequential activation was adjusted to keep the leading edge temperature equal between the pads. We created Finite Element Method computer models of three pads (5 × 5 cm, 1 cm apart) placed in line with the RF electrode on a human thigh to determine differences in tissue heating during simultaneous and sequential ground pad activation. We performed experiments with three ground pads (5 × 10 cm, 4 cm apart) placed on a tissue phantom (1.5 A, 12 min) and measured pad surface and leading edge temperatures.

Results: Temperature rise below the leading edge for proximal, middle and distal ground pad in relation to active electrode location was 5.9°C ± 0.1°C, 0.8°C ± 0.1°C and 0.3°C ± 0.1°C for conventional operation, and 3.3°C ± 0.1°C, 3.4°C ± 0.2°C and 3.4°C ± 0.2°C for sequentially activated operation in the experiments (p < 0.001).

Conclusion: Sequential activation of multiple ground pads resulted in reduced maximum tissue temperature. This may reduce the incidence of ground pad burns and may allow higher power RF generators.     

Ablation therapy of non-colorectal cancer lung metastases: retrospective analysis of tumour response post-laser-induced interstitial thermotherapy (LITT), radiofrequency ablation (RFA) and microwave ablation (MWA)

Purpose: To retrospectively compare the local tumour response and survival rates in patients with non-colorectal cancer lung metastases post-ablation therapy using laser-induced thermotherapy (LITT), radiofrequency ablation (RFA) and microwave ablation (MWA).

Material and methods: Retrospective analysis of 175 computed tomography (CT)-guided ablation sessions performed on 109 patients (43 males and 66 females, mean age: 56.6 years). Seventeen patients with 22 lesions underwent LITT treatment (tumour size: 1.2–4.8?cm), 29 patients with 49 lesions underwent RFA (tumour size: 0.8–4.5?cm) and 63 patients with 104 lesions underwent MWA treatment (tumour size: 0.6–5?cm). CT scans were performed 24-h post-therapy and on follow-up at 3, 6, 12, 18 and 24 months.

Results: The overall-survival rates at 1-, 2-, 3- and 4-year were 93.8, 56.3, 50.0 and 31.3% for patients treated with LITT; 81.5, 50.0, 45.5 and 24.2% for patients treated with RFA and 97.6, 79.9, 62.3 and 45.4% for patients treated with MWA, respectively. The mean survival time was 34.14 months for MWA, 34.79 months for RFA and 35.32 months for LITT. In paired comparison, a significant difference could be detected between MWA versus RFA (p?=?0.032). The progression-free survival showed a median of 23.49?±?0.62 months for MWA,19.88?±?2.17 months for LITT and 16.66?±?0.66 months for RFA (p?=?0.048). The lowest recurrence rate was detected in lesions ablated with MWA (7.7%; 8 of 104 lesions) followed by RFA (20.4%; 10 of 49 lesions) and LITT (27.3%; 6 of 22 lesions) p value of 0.012. Pneumothorax was detected in 22.16% of MWA ablations, 22.73% of LITT ablations and 14.23% of RFA ablations.

Conclusion: LITT, RFA and MWA may provide an effective therapeutic option for non-colorectal cancer lung metastases with an advantage for MWA regarding local tumour control and progression-free survival rate.