Thermal Ablation Of Tumors Research Articles

Role of magnetic nanoparticle (MNPs) in cancer treatment: A review

Cancer is a group of over one hundred diseases featured by incontinent, uncoordinated cell division occur when primitive reproductive process lost the authority unlike normal cells to produce harmful immature cells in the body. Nanosystem in particular themagnetic nanoparticles (MNPs) have been advanced and explored in recent years with wide use in tumor targeting in oncology to conquer the incontinent growth of proliferating cells. The MNPs are kind of smart, highly functionalized, biocompatible coated nanostructures with intrinsic magnetic properties of magnetic response of assembling and positioning, heat absorption, ferromagnetism and super paramagnetism in vivo at the specific site under the enforced alternating external magnetic field and makes them the most promising tool and design with reduced the probability of resistance that provides theranostics (multimodal and functional) platform for cancer diagnosis (imaging and monitoring), and magnet targeted controlled delivery of therapeutics in cancer therapy. The iron oxide based MNPs like Fe3O4 (magnetite) and γ-Fe2O3 (maghemite) are the widely explored nanostructures because of their lowest toxicity and viable biocompatibility in oncology with wide biomedical application in MRI contrast agent, MDT, MHT, PDT and PTT. This review put light on the various aspects of MNPs including its synthetic routes, biomedical application spectra in cancer investigations such as imaging, diagnosis, magnet drug targeting, genetic medication and tumor thermal ablation therapy with its future perspectives and challenges.

Real-time US/cone-beam CT fusion imaging for percutaneous ablation of small renal tumours: a technical note.

Fusion imaging is gaining attention as an imaging technique to assist minimally invasive tumour ablation. Ultrasound (US) and computed tomography (CT) are the most common imaging modalities to guide thermal ablation of renal tumours, yet cone-beam CT (CBCT) has recently been described to successfully assist percutaneous renal interventions. Our goal was to evaluate primary technical success and correct lesion targeting of US/CBCT fusion imaging to guide the ablation of kidney masses < 2 cm in a small group of patients. Six renal lesions (maximum diameter 11-17 mm) were treated with RFA in 5 different patients using real-time US/CBCT. Fusion imaging was used to identify and monitor tumour ablation. Demographics, tumour characteristics and mean serum creatinine levels were recorded before and after the procedure. Primary technical success and correct lesion targeting represented the main endpoints of the study. Primary technique efficacy was confirmed at 1-month and 3-month contrast-enhanced CT follow-ups. In all cases, a confident US/CBCT synchronisation was reached and allowed for a correct targeting and a successful percutaneous ablation. Primary technique efficacy was 100%. No recurrence was observed at the follow-up that ranged from 8 to 26 months (mean 16 months). US/CBCT fusion proved to be a viable method to precisely guide safe and effective percutaneous thermal ablation in patients with small renal tumours, especially when hardly detectable on US. • US/CBCT fusion imaging for renal ablation is safe and feasible. • US/CBCT fusion imaging allows for an improved targeting and complete ablation of small RCC with poor US-conspicuity.

Advances in Ultrasound Tissue Characterization and Its Application in Thermal Ablation of Tumors

The methods of monitoring the thermal ablation of tumor are compared and analyzed in recent years. The principle method results and insufficient of ultrasound elastography and quantitative ultrasound imaging are discussed. The results show that ultrasonic tissue signature has great development space in the field of real-time monitoring of thermal ablation, but there are still some problems such as insufficient monitoring accuracy difficulty in whole-course monitoring and insufficient in vivo experiments, so it is impossible to realize clinical application. It is necessary to further study the monitoring method which can realize accurate and real-time detection of ablation zone and transition zone and can be easily combined with the existing ultrasonic equipment.

NIR Dye-Conjugated Maltodextrin for Photothermal Therapy of Cancer

Photothermal therapy (PTT) is one of recently emerging anticancer treatment modalities that involve the use of laser and photosensitizers. To fully explore the therapeutic potential of PTT, it is critical to deliver photosensitizers to tumors specifically. Maltodextrin is a hydrophilic polysaccharide consisting of D-glucose units and has been used as a pharmaceutical excipient because of its excellent biocompatibility. IR820 is a derivative of indocyanine green (ICG), a clinically used imaging agent and has potential as a photosensitizer for PTT. However, the clinical translation of IR820 has been limited by its lack of cancer targeting ability and poor stability in physiological environments. In this study, we hypothesized that IR820-conjugated maltodextrin (MDir) preferentially accumulates in tumors and serves as photothermal agents. Combination of MDir and near-infrared (NIR) laser irradiation significantly increased the temperature, leading to photothermal-mediated apoptosis of cancer cells. In a mouse xenograft models, MDir preferentially accumulated in tumors and induced almost complete thermal ablation of tumors upon NIR laser irradiation. Based on its tumor targeting ability, photothermal conversion efficiency and excellent biocompatibility, we anticipate that MDir holds great translational potential as a fluorescence imaging-guided photothermal agent for cancer treatment.

Ataxia telangiectasia mutated inhibitor-loaded copper sulfide nanoparticles for low-temperature photothermal therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most frequent type of primary liver cancer, and is ranked the sixth most common neoplasm and the third leading cause of cancer-related deaths. Photothermal therapy (PTT) for thermal ablation of local tumors has recently emerged as a therapeutic strategy. However, the relatively high temperature of over 50 °C may lead to unexpected heat-related damage to tumor-adjacent normal tissues. Herein, we designed and synthesized ataxia telangiectasia mutated (ATM) inhibitor loaded hollow-structured CuS NPs with surface modification with anti-TGF-β antibody (CuS-ATMi@TGF-β NPs). CuS-ATMi@TGF-β NPs are highly photo-stable, can release encapsulated drugs, and increase the temperature to an effective level in a near-infrared (NIR)-responsive manner. Moreover, CuS-ATMi@TGF-β NPs specifically target tumors and thereby significantly inhibit tumor growth on contribution to synergistic low-temperature PTT and chemotherapy. This system not only achieved low-temperature PTT but also resulted in reduced damage to normal tissues. Modification with anti-TGF-β antibody enhanced target specificity and immune activation. The combination of PTT and ATM inhibitor showed synergistic effects and significantly attenuated the growth of the HCC via down regulation of heat shock protein (HSP). CuS-ATMi@TGF-β NPs are a highly promising platform for targeted tumor ablation via hyperthermia-mediated tumor death with minimal damage to normal tissues at a low temperature. Statement of significanceWe constructed ataxia telangiectasia mutated (ATM) inhibitor-loaded hollow-structured CuS NPs with surface modification with anti-TGF-β antibody (CuS-ATMi@TGF-β NPs). CuS-ATMi@TGF-β NPs not only achieved low-temperature photothermal therapy (PTT) but also resulted in reduced damage to normal tissues and sufficient biocompatibility. The modification with anti-TGF-β antibody enhanced targeted specificity, cell endocytosis, and immune activation. In addition, the combination of PTT and ATM inhibitor synergistically attenuated the growth of the HCC via downregulation of heat shock protein (HSP). This study provided proof-of-concept for the ATM inhibitor that mediated low-temperature PTT with a potential for future clinical applications.

Volumetric Quantitative Ablation Margins for Assessment of Ablation Completeness in Thermal Ablation of Liver Tumors.

BackgroundIn thermal ablation of liver tumors, complete coverage of the tumor volume by the ablation volume with a sufficient ablation margin is the most important factor for treatment success. Evaluation of ablation completeness is commonly performed by visual inspection in 2D and is prone to inter-reader variability. This work aimed to introduce a standardized approach for evaluation of ablation completeness after CT-guided thermal ablation of liver tumors, using volumetric quantitative ablation margins (QAM).MethodsA QAM computation metric based on volumetric segmentations of tumor and ablation areas and signed Euclidean surface distance maps was developed, including a novel algorithm to address QAM computation in subcapsular tumors. The code for QAM computation was verified in artificial examples of tumor and ablation spheres simulating varying scenarios of ablation margins. The applicability of the QAM metric was investigated in representative cases extracted from a prospective database of colorectal liver metastases (CRLM) treated with stereotactic microwave ablation (SMWA).ResultsApplicability of the proposed QAM metric was confirmed in artificial and clinical example cases. Numerical and visual options of data presentation displaying substrata of QAM distributions were proposed. For subcapsular tumors, the underestimation of tumor coverage by the ablation volume when applying an unadjusted QAM method was confirmed, supporting the benefits of using the proposed algorithm for QAM computation in these cases. The computational code for developed QAM was made publicly available, encouraging the use of a standard and objective metric in reporting ablation completeness and margins.ConclusionThe proposed volumetric approach for QAM computation including a novel algorithm to address subcapsular liver tumors enables precision and reproducibility in the assessment of ablation margins. The quantitative feedback on ablation completeness opens possibilities for intra-operative decision making and for refined analyses on predictability and consistency of local tumor control after thermal ablation of liver tumors.

Image-Guided Percutaneous Thermal Ablation of Oligometastatic Ovarian and Non-Ovarian Gynecologic Tumors

PurposeTo assess the safety, feasibility, and efficacy of percutaneous thermal ablation (TA) in the treatment of metastatic gynecologic (GYN) tumors. Materials and MethodsA study cohort of 42 consecutive women (mean age, 59. years; range, 25–78 years) with metastatic GYN tumors (119 metastatic tumors) treated with radiofrequency (n = 47 tumors), microwave (n = 47 tumors), or cryogenic (n = 30 tumors) ablation from over 2,800 ablations performed from January 2001 to January 2019 was identified. The primary GYN neoplasms consisted of ovarian (27 patients; 77 tumors; mean tumor diameter [MTD], 2.50 cm), uterine (7 patients; 26 tumors; MTD, 1.89 cm), endometrial (5 patients; 10 tumors; MTD, 2.8 cm), vaginal (2 patients; 5 tumors; MTD, 2.40 cm), and cervical (1 patient; 1 tumor; MTD, 1.90 cm) cancers. In order of descending frequency, metastatic tumors treated by TA were located in the liver or liver capsule (74%), lungs (13%), and peritoneal implants (9%). Single tumors were also treated in the kidneys, rectus muscle, perirectal soft tissue (2.5%), and retroperitoneal lymph nodes (1.6%). All efficacy parameters of TA and definitions of major and minor adverse events are categorized by the latest Society of Interventional Radiology reporting standards. ResultsThe median follow-up of treated patients was 10 months. After the initial ablation, 95.6% of the patients achieved a complete tumor response confirmed by contrast-enhanced magnetic resonance imaging or computed tomography. On surveillance imaging, 8.5% of the ablated tumors developed local progression over a median follow-up period of 4.1 months. Five of 8 tumors with local recurrence underwent repeated treatment over a mean follow-up period of 18 months, and 4 of 5 tumors achieved complete eradication after 1 additional treatment session that resulted in a secondary efficacy of 80%. The overall technique efficacy of TA was 96.2% over a median follow-up period of 10 months. ConclusionsTA was safe and effective for the local control of metastatic GYN tumors in the lungs, abdomen, and pelvis, with an overall survival rate of 37.5 months and a local progression-free survival rate of 16.5 months, with only 4.8% of treated patients experiencing a major adverse event.

Feasibility of 3D US/CEUS-US/CEUS fusion imaging-based ablation planning in liver tumors: a retrospective study.

To assess the feasibility of ablation planning based on fusion imaging of three-dimensional ultrasound/contrast-enhanced ultrasound (3D US/CEUS) with real-time US/CEUS for liver tumor thermal ablation. Between January 2017 and December 2018, 85 hepatic tumors from 82 patients who underwent percutaneous ablation were included. First, intraprocedural 3D US/CEUS imaging was performed for ablation planning. Then, fusion imaging of 3D US/CEUS with real-time US/CEUS was used to guide the implementation of the plan, immediately evaluate the technical success and indicate the need for supplemental ablation. In addition, contrast-enhanced CT/MR imaging was performed 1month after the procedure to evaluate the presence of residual tumors, and follow-up scans were repeated every 3months. The average liver tumor diameter was 28 ± 9mm (range, 10-55mm). 3D US/CEUS-based planning was successfully conducted in all 85 tumors with a 100% technical success rate of planning. The immediate evaluation by 3D CEUS/US-CEUS fusion imaging showed a 100% technical success rate of ablation. The 1-month CT/MR scans found a residual tumor in one intrahepatic cholangiocarcinoma patient; the technique efficacy rate was 98.8%. The median follow-up period was 21.5months (IQR: 4-36months). During the follow-up period, the local tumor progression rate was 5.9% (5/84), and no major procedure-related complications occurred. Ablation planning based on 3D US/CEUS-US/CEUS fusion imaging is feasible for liver tumors.

Percutaneous thermal ablation of hepatic tumors: local control efficacy and risk factors for artificial ascites failure

Objective To investigate the risk factors affecting the technical failure of artificial ascites (AA) formation and to evaluate the local control efficacy of percutaneous thermal ablation assisted by the AA for hepatic tumors. Methods A total of 341 patients with 362 hepatic tumors who underwent thermal ablation assisted by AA were reviewed retrospectively. The technical success of AA, the volume of liquid, and local efficacy after ablation were assessed. Predictive factors for the technical failure of AA formation and local tumor progression (LTP) were analyzed using univariate and multivariate analysis. Results The technical success rate of AA formation was 81.8% (296/362). The amount of fluid was higher when the tumor was located in the left lobe of the liver than when it was located in the right lobe (median 950 ml versus 700 ml, p < 0.001). Previous hepatic resection (OR: 12.63, 95% CI: 2.93–54.45, p < 0.001), ablation (OR: 6.48, 95% CI: 1.36–30.92, p = 0.019) and upper-abdomen surgery (OR: 11.34, 95% CI: 1.96–65.67, p = 0.007) were the independent risk factors of AA failure. In the AA success group, the complete ablation rate was higher and the LTP rate was lower than that in the AA failure group (98.7 versus 92.4%, p = 0.012; 8.8 versus 21.2%, p = 0.004). Multivariate analysis identified AA failure (p = 0.004), tumor size (>3.0 cm) (p = 0.002) and metastatic liver tumor (p = 0.008) as independent risk factors for LTP. Conclusion History of hepatic resection, ablation and upper abdomen surgery were significant predictive factors affecting the technical failure of AA formation. Successful introduction of AA before thermal ablation can achieve better local tumor control efficacy.

Incomplete thermal ablation of tumors promotes increased tumorigenesis

Purpose While systemic tumor-stimulating effects can occur following ablation of normal liver linked to the IL-6/HGF/VEGF cytokinetic pathway, the potential for tumor cells themselves to produce these unwanted effects is currently unknown. Here, we study whether partially treated tumors induce increased tumor growth post-radiofrequency thermal ablation (RFA). Methods Tumor growth was measured in three immunocompetent, syngeneic tumor models following partial RFA of the target tumor (in subcutaneous CT26 and MC38 mouse colorectal adenocarcinoma, N = 14 each); and in a distant untreated tumor following partial RFA of target subcutaneous R3230 rat breast adenocarcinoma (N = 12). Tumor cell proliferation (ki-67) and microvascular density (CD34) was assessed. In R3230 tumors, in vivo mechanism of action was assessed following partial RFA by measuring IL-6, HGF, and VEGF expression (ELISA) and c-Met protein (Western blot). Finally, RFA was performed in R3230 tumors with adjuvant c-Met kinase inhibitor or VEGF receptor inhibitor (at 3 days post-RFA, N = 3/arm, total N = 12). Results RFA stimulated tumor growth in vivo in residual, incompletely treated surrounding CT26 and MC38 tumor at 3–6 days (p < 0.01). In R3230, RFA increased tumor growth in distant tumor 7 days post treatment compared to controls (p < 0.001). For all models, Ki-67 and CD34 were elevated (p < 0.01, all comparisons). IL-6, HGF, and VEGF were also upregulated post incomplete tumor RFA (p < 0.01). These markers were suppressed to baseline levels with adjuvant c-MET kinase or VEGF receptor inhibition. Conclusion Incomplete RFA of a target tumor can sufficiently stimulate residual tumor cells to induce accelerated growth of distant tumors via the IL-6/c-Met/HGF pathway and VEGF production.

Numerical analysis of the pulsating heat source effects in a tumor tissue

Background and objectivesHyperthermia treatment is nowadays recognized as the fourth additional cancer therapy technique following surgery, chemotherapy, and radiation; it is a minimally or non-invasive technique which involves fewer complications, a shorter hospital stay, and fewer costs. In this paper, pulsating heat effects on heat transfer in a tumor tissue under hyperthermia are analyzed. The objective of the paper is to find and quantify the advantages of pulsatile heat protocols under different periodical heating schemes and for different tissue morphologies. MethodsThe tumor tissue is modeled as a porous sphere made up of a solid phase (tissue, interstitial space, etc.) and a fluid phase (blood). A Local Thermal Non-Equilibrium (LTNE) model is employed to consider the local temperature difference between the two phases. Governing equations with the appropriate boundary conditions are solved with the finite-element code COMSOL Multiphysics®. The pulsating effect is modeled with references to a cosine function with different frequencies, and such different heating protocols are compared at equal delivered energy, i. e. different heating times at equal maximum power. ResultsDifferent tissue properties in terms of blood vessels sizes and blood volume fraction in tissue (porosity) are investigated. The results are shown in terms of tissue temperature and percentage of necrotic tissue obtained. The most powerful result achieved using a pulsating heat source instead of a constant one is the decreasing of maximum temperature in any considered case, even reaching about 30% lower maximum temperatures. Furthermore, the evaluation of tissue damage at the end of treatment shows that pulsating heat allows to necrotize the same tumoral tissue area of the non-pulsating heat source. ConclusionsModeling pulsating heat protocols in thermal ablation under different periodical heating schemes and considering different tissues morphologies in a tumor tissue highlights how the application of pulsating heat sources allows to avoid high temperature peaks, and simultaneously to ablate the same tumoral area obtained with a non-pulsating heat source. This is a powerful result to improve medical protocols and devices in thermal ablation of tumors.

Transcholecystic Contrast-Enhanced Ultrasound-Guided Percutaneous Transhepatic Biliary Drainage for Central Bile Duct Protection During Thermal Tumor Ablation

Intraductal cooling via a percutaneous transhepatic biliary drainage tube holds great promise in facilitating thermal ablation of liver tumors adjacent to the central bile ducts. However, the difficulties and complications associated with puncturing nondilated bile ducts are greater than those associated with puncturing dilated bile ducts. As reported here, percutaneous transcholecystic contrast-enhanced ultrasound was performed in 7 patients to visualize the nondilated bile ducts and guide percutaneous transhepatic biliary drainage, thus facilitating the intraductal cooling-assisted thermal ablation process. The procedures were technically successful in all 7 patients, and no major complications were recorded during the follow-up period.

Multiple objective planning for thermal ablation of liver tumors.

Preoperative treatment planning is key to ensure successful thermal ablation of liver tumors. The planning aims to minimize the number of electrodes required for complete ablation and the damage to the surrounding tissues while satisfying multiple clinical constraints. This is a challenging multiple objective planning problem, in which the trade-off between different objectives must be considered. We propose a novel method to solve the multiple objective planning problem, which combines the set cover-based model and Pareto optimization. The set cover-based model considers multiple clinical constraints and generates several clinically feasible treatment plans, among which the Pareto optimization is performed to find the trade-off between different objectives. We evaluated the proposed method on 20 tumors of 11 patients in two different situations used in common thermal ablation approaches: with and without the pull-back technique. Pareto optimal plans were found and verified to be clinically acceptable in all cases, which can find the trade-off between the number of electrodes and the damage to the surrounding tissues. The proposed method performs well in the two different situations we considered: with or without the pull-back technique. It can generate Pareto optimal plans satisfying multiple clinical constraints. These plans consider the trade-off between different planning objectives.

Is There a Role for Combination, Single-Session Selective Transarterial Embolization and Microwave Ablation for Large Renal Masses?

Thermal ablation of small renal tumors is safe and efficacious. Thermoablation of tumors greater than 3cm has decreased efficacy and a greater risk of complications. Combined embolization and radiofrequency ablation has shown encouraging results. We report on the use of combined single-session transarterial embolization and microwave ablation to treat large renal masses. After obtaining IRB approval, a review of the medical record between October 2016 and January 2020 was performed. Patients with renal tumors who underwent combined transarterial embolization and microwave ablation were assessed retrospectively. Patient demographic information, intraoperative, postoperative, and follow-up data were recorded. Eleven patients were identified meeting inclusion criteria. The mean age was 73years, with 64% male, an average BMI of 26.5, and average Charleston Comorbidity Index of 6.7. Nine tumors were identified as clear cell carcinoma, one as papillary carcinoma and one as an oncocytic neoplasm. Average tumor size was 4.5cm (2.7-8.3), with an average RENAL score of 8.5. Successful ablation with a 5mm margin was achieved in all patients, and in all cases, ablation and embolization were performed on the same day. The only related post-procedure complication was a single groin hematoma. Surveillance was performed with CT or MRI. Average follow-up was 419.5days (range 27-747), with no patients showing evidence of recurrence to date. Combined single-session transarterial embolization and microwave ablation is technically feasible, safe, and efficacious in treating large renal tumors in a series of 11 patients with no recurrence to date. Level 4, case series.

SLIR: Synthesis, localization, inpainting, and registration for image-guided thermal ablation of liver tumors.

Thermal ablation is a minimally invasive procedure for treating small or unresectable tumors. Although CT is widely used for guiding ablation procedures, yet the contrast of tumors against normal soft tissues is often poor in CT scans, aggravating the accurate thermal ablation. In this paper, we propose a fast MR-CT image registration method to overlay pre-procedural MR (pMR) and pre-procedural CT (pCT) images onto an intra-procedural CT (iCT) image to guide the thermal ablation of liver tumors. At the pre-procedural stage, the Cycle-GAN model with mutual information constraint is employed to generate the synthesized CT (sCT) image from the input pMR. Then, pMR-pCT image registration is carried out via traditional mono-modal sCT-pCT image registration. At the intra-procedural stage, the region of the probe and its artifacts are automatically localized and inpainted in the iCT image. Then, an unsupervised registration network (UR-Net) is used to efficiently align the pCT with the inpainted iCT (inpCT) image. The final transform from pMR to iCT is obtained by concatenating the two estimated transforms, i.e., (i) from pMR image space to pCT image space (via sCT) and (ii) from pCT image space to iCT image space (via inpCT). The proposed method has been evaluated over a real clinical dataset and compared with state-of-the-art methods. Experimental results confirm that the proposed method achieves high registration accuracy with fast computation speed.

Promising abscopal effect of combination therapy with thermal tumour ablation and intratumoural OK-432 injection in the rat osteosarcoma model

Treatment options for metastatic osteosarcoma are limited. The present study aimed to evaluate whether radiofrequency ablation (RFA) combined with intratumoural OK-432 injection induces systemic anti-tumour immunity in rat osteosarcoma model. Eighty of 145 rats were assigned to four groups to evaluate overall survival and tumour size: control (no treatment), RFA-only, OK-432, and RFA-OK-432. The remaining 65 were assigned for histological examination. Maximum diameters of tibial and lung tumours were determined. Tumour samples were histologically examined using haematoxylin-eosin and immunohistochemical staining. Overall survival was significantly prolonged in the RFA-OK-432 group compared to the RFA-only and OK-432 groups. Only rats in the RFA-OK-432 group exhibited significant decreases in maximum tumour diameter after treatment. Ki-67-positive tumour cells in the RFA-OK-432 group were significantly stained negative on immunohistochemical analysis as opposed to those in the RFA-only and OK-432 groups. The number of CD11c+, OX-62+, CD4+, and CD8 + cells significantly increased in the RFA-OK-432 group compared to the RFA-only group. RFA with intratumoural OK-432 injection resulted in distant tumour suppression, prolonged survival, and increased dendritic cells, cytotoxic T cells, IFN-γ, and TNF-α, whereas RFA or OK-432 alone did not produce this effect. This combination may induce an abscopal effect in human osteosarcoma.

Use of microwave ablation for thermal treatment of solid tumors with different shapes and sizes-A computational approach.

Microwave Ablation (MWA) is one of the most recent developments in the field of thermal therapy. This approach is an effective method for thermal tumor ablation by increasing the temperature above the normal physiological threshold to kill cancer cells with minimum side effects to surrounding organs due to rapid heat dispersive tissues. In the present study, the effects of the shape and size of the tumor on MWA are investigated. To obtain the temperature gradient, coupled bio-heat and electromagnetic equations are solved using a three-dimensional finite element method (FEM). To extract cellular response at different temperatures and times, the three-state mathematical model was employed to achieve the ablation zone size. Results show that treatment of larger tumors is more difficult than that of smaller ones. By doubling the diameter of the tumor, the percentage of dead cancer cells is reduced by 20%. For a spherical tumor smaller than 2 cm, applying 50 W input power compared to 25 W has no significant effects on treatment efficiency and only increases the risk of damage to adjacent tissues. However, for tumors larger than 2 cm, it can increase the ablation zone up to 21%. In the spherical and oblate tumors, the mean percentage of dead cells at 6 GHz is nearly 30% higher than that at 2.45GHz, but for prolate tumors, treatment efficacy is reduced by 10% at a higher frequency. Moreover, the distance between two slots in the coaxial double slot antenna is modified based on the best treatment of prolate tumors. The findings of this study can be used to choose the optimum frequency and the best antenna design according to the shape and size of the tumor.

Biodegradable magnesium alloy with eddy thermal effect for effective and accurate magnetic hyperthermia ablation of tumors.

Magnetic hyperthermia therapy (MHT) is able to ablate tumors using an alternating magnetic field (AMF) to heat up magnetocaloric agents (e.g. magnetic nanoparticles) administered into the tumors. For clinical applications, there is still a demand to find new magnetocaloric agents with strong AMF-induced heating performance and excellent biocompatibility. As a kind of biocompatible and biodegradable material, magnesium (Mg) and its alloys have been extensively used in the clinic as an implant metal. Herein, we discovered that the eddy thermal effect of the magnesium alloy (MgA) could be employed for MHT to effectively ablate tumors. Under low-field-intensity AMFs, MgA rods could be rapidly heated, resulting in a temperature increase in nearby tissues. Such AMF-induced eddy thermal heating of MgA could not only be used to kill tumor cells in vitro, but also be employed for effective and accurate ablation of tumors in vivo. In addition to killing tumors in mice, we further demonstrated that VX2 tumors of much larger sizes growing in rabbits after implantation of MgA rods could also be eliminated after exposure to an AMF, illustrating the ability of MgA-based MHT to kill large-sized tumors. Moreover, the implanted MgA rods showed excellent biocompatibility and ∼20% of their mass was degraded within three months. Our work thus discovered for the first time that non-magnetic biodegradable MgA, an extensively used implant metal in clinic, could be used for effective magnetic thermal ablation of tumors under a low-field-intensity AMF. Such a strategy could be readily translated into clinical use.

Management of Residual or Recurrent Disease Following Thermal Ablation of Renal Cortical Tumors.

Management of residual or recurrent disease following thermal ablation of renal cortical tumors includes surveillance, repeat ablation, or surgical extirpation. We present a multicenter experience with regard to the management of this clinical scenario. Prospectively maintained databases were reviewed to identify 1265 patients who underwent cryoablation (CA) or radiofrequency ablation (RFA) for enhancing renal masses. Disease persistence or recurrence was classified into one of the three categories: (i) residual disease in ablation zone; (ii) recurrence in the ipsilateral renal unit; and (iii) metastatic/extra-renal disease. Seventy seven patients (6.1%) had radiographic evidence of disease persistence or recurrence at a median interval of 13.7 months (range, 1–65 months) post-ablation. Distribution of disease included 47 patients with residual disease in ablation zone, 29 with ipsilateral renal unit recurrences (all in ablation zone), and one with metastatic disease. Fourteen patients (18%) elected for surveillance, and the remaining underwent salvage ablation (n = 50), partial nephrectomy (n = 5), or radical nephrectomy (n = 8). Salvage ablation was successful in 38/50 (76%) patients, with 12 failures managed by observation (3), tertiary ablation (6), and radical nephrectomy (3). At a median follow-up of 28 months, the actuarial cancer-specific survival and overall survival in this select cohort of patients was 94.8 and 89.6%, respectively.

Interventional radiology for treatment of bone metastases

Therapeutic advances in oncology have led to longer survival in many forms of cancer, including those complicated by bone metastases. When a bone metastasis is painful or when there is a risk of fracture, interventional radiology procedures can be carried out for pain control and/or stabilisation. All of these techniques can be performed under local anaesthesia. Cementoplasty and vertebroplasty are stabilisation procedures consisting in the percutaneous injection of acrylic cement into a lytic bone lesion. The effect on pain can be explained by the consolidation of weakened, fractured or pre-fractured bone, but also to a lesser extent by the toxic, chemical and thermal effect of the cement. Tumour ablation techniques include alcoholisation or thermal ablation (by heat with radiofrequency and microwave or cold by cryoablation). Percutaneous thermal ablation of bone tumours is most often performed as a palliative measure resulting in a significant and lasting reduction in symptoms. Radiofrequency ablation consists in placing needles through which an electrical current passes. Microwave ablation acts by causing very high frequency vibrations of water molecules. Cryoablation releases argon gas at the tip of the needle, forming an “ice ball” effectively destroying tumour cells. Any of these techniques can be combined to radiation therapy, performed before or after radiation. Finally, tumour embolisation can have a goal of pain control, or preparation of surgery to reduce the risk of peroperative haemorrhage.