Temperature-correlated histopathologic changes following microwave thermoablation of obstructive tissue in patients with benign prostatic hyperplasia

Strongly quenched activatable theranostic nanogel for precision imaging-guided photodynamic therapy and enhanced immunotherapy

Immune checkpoint inhibitors (ICIs) are innovative immunotherapeutic agents for cancer. However, their low therapeutic efficacy in patients with large or rapidly growing tumors, along with their high cost, represents a notable limitation in their clinical applications. Therefore, new and safe strategies must be developed to enhance the therapeutic efficacy of ICIs in clinical settings. In this study, we developed a near-infrared (NIR) fluorescent dye-loaded activatable theranostic nanogel (NATNgel) for precision imaging-guided photodynamic therapy (PDT) and combined immunotherapy for rapidly growing tumors. Although NIR fluorescence and phototoxicity of NATNgel are strongly quenched, these can be selectively activated inside target tumor cells. A high tumor-to-background ratio (7.31 ± 1.40) in NIR fluorescence imaging could be achieved in NATNgel-treated mice, enabling real-time image-guided PDT. The combination of PDT and anti-PD-1 antibody therapy resulted in complete tumor regression. Histopathological evaluation of major organs and blood chemistry analysis revealed no side effects of the combined treatment regimen. In addition, the combination treatment completely suppressed the growth of rechallenged tumors. Overall, NATNgel is a safe and promising theranostic material for precision imaging-guided PDT and enhanced immunotherapy.

The Impact of Perilesional Heatsink Structures on Ablation Volumes in Laser Interstitial Thermal Therapy for Brain Metastases

BACKGROUND AND OBJECTIVES

Laser interstitial thermal therapy (LITT) has demonstrated promise in surgical neuro-oncology because of its effectiveness in delivering precise thermal energy to lesions. The extent of ablation (EOA) is a prognostic factor in improving patient outcomes but is often affected by perilesional heatsink structures, which can lead to asymmetric ablations. The purpose of this study was to quantitatively evaluate the impact of various perilesional heatsink structures on the EOA in LITT for brain metastases.

METHODS

Twenty-seven procedures for 22 unique patients with brain metastases fit the inclusion criteria. Intracranial heatsink structures were identified: sulci, meninges, cerebrospinal fluid (CSF) spaces, and vasculature. Asymmetric ablation was determined by measuring 3 pairs of orthogonal distances from the proximal, midpoint, and distal locations along the laser catheter to the farthest edge of the ablation zone bilaterally. Distances from the same points on the laser catheter to the nearest heatsink were also recorded. The Heatsink Effect Index was created to serve as a proxy for asymmetric ablation. Pearson correlations, t -tests, and analysis of variance were the statistical analyses performed.

RESULTS

From the midpoint of the catheter, the 27 heatsinks were meninges (40.7%), sulci (22.2%), vasculature (22.2%), and CSF spaces (14.8%). Across all points along the catheter track, there was a significant generalized heatsink effect on asymmetric ablations ( P < .0001). There was a negative correlation observed between asymmetric ablations and EOA from the midpoint of the laser catheter (r = -0.445, P = .020). Compared with sulci, CSF spaces trended toward a greater effect on asymmetric ablation volumes ( P = .069).

CONCLUSION

This novel quantitative analysis shows that perilesional heatsinks contribute to asymmetric ablations. CSF spaces trended toward higher degrees of asymmetric ablations. Importantly, neurosurgeons may anticipate asymmetric ablations preoperatively if heatsinks are located within 13.3 mm of the laser probe midpoint. These preliminary results may guide surgical decision-making in LITT for metastatic brain lesions.

Non-surgical ablation for breast cancer: an emerging therapeutic option

Non-surgical ablation is emerging as an alternative local therapy option for patients with early-stage breast cancer and encompasses two main types of percutaneous therapeutic procedures: radiofrequency ablation and cryoablation. Both techniques involve obliteration of a spherical lesion and feasibility studies have shown that complete tumour ablation is achievable with good or excellent cosmetic results. Although few clinical studies have directly compared non-surgical ablation with conventional surgical resection, observational studies indicate that clinical outcomes are favourable with acceptable rates of local control and no detriment to long-term survival. There remain outstanding issues with these percutaneous ablative techniques that require resolution before they could be incorporated into routine clinical practice. Hence, a consensus meeting was convened to discuss the challenges of non-surgical ablation and clarify indications for its use alongside clinical management pathways. In this Policy Review we will address some of the broader biological aspects of non-surgical ablation, including immune-modulatory effects and potential novel applications for the future.

Synchronous Microwave Ablation Combined With Cisplatin Intratumoral Chemotherapy for Large Non-Small Cell Lung Cancer

BACKGROUND

Microwave ablation (MWA) and intratumoral chemotherapy (ITC) are useful for treating tumors in animal models; however, their clinical use in patients with large non-small cell lung cancer (NSCLC) remains unknown. This retrospective study aimed to evaluate preliminary outcomes of MWA + ITC for large NSCLC.

METHODS

From November 2015 to April 2020, a total of 44 NSCLC patients with a mean lesion diameter of 6.1 ± 1.5 cm were enrolled and underwent synchronous MWA + ITC procedures. The primary endpoint was local progression-free survival (LPFS); secondary endpoints were progression-free survival (PFS), complications, overall survival (OS), and associated prognostic factors.

RESULTS

The median follow-up time was 19.0 months. At the 1-month CT scan, complete tumor ablation was observed in 47.7% of cases. Median LPFS was 12.1 months; 1-, 2-, and 3-year LPFS rates were 51.2%, 27.9%, and 13.6%, respectively. A shorter LPFS was significantly associated with large lesions (HR 1.23, 95% CI 1.02-1.49; p = 0.032). Median PFS was 8.1 months; 1-, 2-, and 3-year PFS rates were 29.5%, 18.2%, and 9.1%, respectively. LPFS was significantly superior to PFS (p = 0.046). Median OS was 18.8 months. The 1-, 2-, 3-, and 5-year OS rates were 65.9%, 43.2%, 26.4%, and 10.0%, respectively. In univariate comparisons, high performance status (PS) score, smoking, and larger lesions were significantly correlated with poor survival. In multivariate analysis, advanced age, higher PS score, higher stage, larger lesion, and prior systematic treatment were independent prognostic factors for shorter OS. Adverse events were well tolerated and all patients recovered after appropriate intervention.

CONCLUSIONS

MWA + ITC is a safe and effective new modality of local treatment for large NSCLC and can significantly prolong LPFS.

Bipolar prostate thermotherapy for the improvement of chronic prostatitis symptoms and ejaculation problems

This study aims to evaluate the efficacy of the new bipolar radiofrequency thermotherapy device (TEMPRO) on urinary and sexual functions in patients with chronic prostatitis. Between April 2017 and September 2018, 42 male patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) were included. The patients had received at least 6 months of treatment via conventional medical treatments. NIH-Chronic Prostatitis Symptom Index (CPSI), International Index of Erectile Function-Erectile Function part (IEEF-EF), and Premature Ejaculation Profile (PEP). The intravaginal ejaculation latency times (IELT) of the patients were recorded before and 6th months after the procedure. Bipolar radiofrequency thermotherapy was applied with TEMPRO system containing a16Fr applicator. The mean age of the patients was 42.62 ± 8.25 years. All patients were treated with local anesthesia, and three patients were unable to complete the procedure. After 6 months, significant improvements were observed in the NIH-CPSI total (20.25 vs. 12.18; p < .001) and subgroup scores, PEP scores (0.98 ± 1.12 vs. 2.06 ± 1.03; p < .001) and IELT (68.24 ± 56.78 vs. 103.02 ± 188.56; p < .001). There was no significant difference between IIEF-EF scores. Symptomatic improvement was observed in 78.57% (33/42) of the patients. Bipolar radiofrequency thermotherapy, which is a transurethral method in patients with CP/CPPS, decreases the severity of the disease and improvement of the symptom scores on urinary and sexual function. Additional studies are required to further evaluate treatment effectiveness.

Bipolar radiofrequency thermotherapy treatment of the prostate in urinary catheter-dependent men

OBJECTIVES

In this study, for the first time in the literature, we evaluated patients with benign prostatic hyperplasia (BPH) who had undergone permanent urinary catheterization for urinary retention and who were treated with radiofrequency (RF) thermotherapy as an alternative method due to their inoperability based on the high risk associated with anesthesia. We aimed to investigate these patients' posttreatment parameters concerning the catheter-free rates, quality of life (QoL) changes, and retrospective treatment efficacy.

METHODS

RF thermotherapy was applied to 62 permanent patients catheterized within the last 3 months due to urinary retention. The follow-up data of the patients were retrospectively analyzed. The patients who were free of catheters and those who required permanent catheterization were determined. The changes in the International Prostate Symptom Score (IPSS), QoL, postvoiding residue (PVR), and maximal flow rate (Q_max ) values were analyzed.

RESULTS

A total of 52 patients were evaluated in terms of treatment success in relation to the elimination of the need for a urinary catheter, which was calculated as 73.07%. The Q_max , IPSS, QoL, and PVR values of 38 patients who no longer required a catheter were monitored for 24 months, and statistically significant changes were observed in all parameters.

CONCLUSION

Bipolar RF thermotherapy was found to be beneficial for men dependent on catheters due to BPH. It can be recommended as a safe, minimally invasive treatment method for elderly patients with a high anesthesia risk.

Effect of bipolar radiofrequency thermotherapy on benign prostate hyperplasia

This study aims to evaluate the safety and efficacy of the new bipolar radiofrequency thermotherapy device (TEMPRO) in treating patients with benign prostate hyperplasia (BPH). Between December 2017 and November 2018, 72 male patients with BPH were included. All patients completed the International Prostate Symptom Score (IPSS) and International Index of Erectile Function-5 (IIEF-5) questionnaires. Physical examinations were performed, and prostate volume, prostatic urethral length and post-voiding residual urine (PVR) were measured using ultrasound. Uroflowmetry was used to calculate the maximum flow rate of urination (Qmax). Bipolar radiofrequency thermotherapy was applied with TEMPRO system containing a 16Fr applicator. All patients were re-evaluated at 6 months post-operatively. The mean age of the patients was 63.22 ± 6.68 years. All patients were treated with local anaesthesia, and three patients were unable to complete the procedure. The median (IQR) visual analogue scale score was 1 (0-3) at 6 hr post-operatively. After 6 months, significant improvements were observed in the IPSS, QoL, Qmax and PVR values of the patients (p < .001 for Qmax, IPSS and QoL; p = .03 for PMR). The success rate of the procedure was similar between patients with prostate volumes <70 and >70 ml. Due to its low rate of complication, the TEMPRO^© treatment is effective in treating BPH, especially among aged patients and those with serious symptoms.

Percutaneous laser ablation for benign and malignant thyroid diseases

Minimally invasive image-guided thermal ablation is becoming increasingly common as an alternative to surgery for the treatment of benign thyroid nodules. Among the various techniques for thermal ablation, laser ablation (LA) is the least invasive, using the smallest applicators available on the market and enabling extremely precise energy deposition. However, in some cases, multiple laser fibers must be used simultaneously for the treatment of large nodules. In this review, the LA technique is described, and its main clinical applications and results are discussed and illustrated.

MR-guided laser interstitial thermal therapy in the treatment of recurrent intracranial meningiomas

OBJECTIVE

Recurrent meningiomas can prove problematic for treatment, especially if anaplastic, as options are limited primarily to surgery and radiation therapy. Laser interstitial thermal therapy (LITT) is a minimally invasive technique for achieving immediate cytoreduction. This study seeks to determine the utility of LITT in the setting of recurrent meningiomas.

MATERIALS AND METHODS

Patients undergoing LITT for tumor treatment at our institution between November 2014 and February 2016 were identified. Those with biopsy-confirmed meningiomas were reviewed with attention to ablation volume, survival, demographic data, and complications. Data from imaging performed at set intervals post-operatively were available for all.

RESULTS

Four patients were identified, three of whom had successful treatment with a total of four ablations. The one case that did not result in a successful ablation was due to problems with stereotactic placing of the laser catheter. One patient had a grade 1 meningioma, with the other two being Grade 3. Immediate ablation volumes averaged 75% of preoperative tumor volume and increased to 97% at 2 weeks before dropping to 65% at 3 months. One patient had acute hemiparesis with speech difficulty, which resolved after 6 months. At date of last follow-up, two of three had progression at an average of nine weeks, and one had no progression at 28 weeks.

CONCLUSION

LITT appeared to be a potentially viable treatment for recurrent meningiomas. Ablation volumes increased over time, but not beyond the initial meningioma volume. Larger studies are needed to better determine complications and outcomes. Lasers Surg. Med. 51:245-250, 2019. © 2018 Wiley Periodicals, Inc.

Theranostic Nanosystems for Targeted Cancer Therapy

Nanomaterials have revolutionized cancer imaging, diagnosis, and treatment. Multifunctional nanoparticles in particular have been designed for targeted cancer therapy by modulating their physicochemical properties to be delivered to the target and activated by internal and/or external stimuli. This review will focus on the fundamental "chemical" design considerations of stimuli-responsive nanosystems to achieve favorable tumor targeting beyond biological barriers and, furthermore, enhance targeted cancer therapy. In addition, we will summarize innovative smart nanosystems responsive to external stimuli (e.g., light, magnetic field, ultrasound, and electric field) and internal stimuli in the tumor microenvironment (e.g., pH, enzyme, redox potential, and oxidative stress).

Laser-Induced Thermal Therapy in Neuro-Oncology: A Review

OBJECTIVES

Laser therapy has become an appealing treatment modality in neurosurgery. In this review, we report on the history, physics, surgical steps, indications and uses, and complications that have been reported to date.

METHODS

An extensive literature search was performed for laser interstitial thermal therapy (LITT) and laser therapy in the context of glial tumors, metastatic lesions, pediatric brain tumors, and radiation necrosis. Reported complications in each series also were reviewed.

RESULTS

In the past decade, multiple studies have demonstrated the use, outcomes, and complications associated with LITT in neurosurgery. These same studies have consistently reported an overall benefit of LITT in cases in which traditional surgical approaches may be limited by the patient's clinical status, tumor location, or overall prognosis. However, there have been complications reported from local effects of thermal damage, technical error, and edema development. Increased experience has reduced complications and brought more promising results.

CONCLUSIONS

With the advent of real-time monitoring and damage estimation, LITT has gained ground in the management of intracranial tumors. Larger scale trials must be performed to develop standard protocols to define specific indications for use. Further large clinical studies for LITT in non-oncologic cases are also of interest.

[Image-guided tumor ablation]

INTRODUCTION

Ablatives techniques for destroying in situ a tumoral process aim tissular necrosis by the application of several physical principles.

MATERIAL AND METHODS

We searched MEDLINE^®, Embase^®, using (MeSH) words; from January 2005 through May 2017, and we looked for all the studies. Investigators graded the strength of evidence in terms of methodology, language and relevance.

RESULTS

Forty-seven articles were analyzed. We described ablative techniques and sorted them in thermal and non-thermal therapies according to the used physical principle and their frequency of use in the urological pathology.

CONCLUSION

Percutaneous ablative therapies are mini-invasive techniques, which have an important role in tumors focal treatment. This article is a review of the ablative therapies and describes their physical principles, their equipment and their recent technological modifications, which have been developed to improve the clinical success of these techniques.

MRI-guided laser interstitial thermal therapy for the treatment of low-grade gliomas in children: a case-series review, description of the current technologies and perspectives

BACKGROUND

Pediatric low-grade gliomas (LGGs) account for approximately half of all pediatric central nervous system tumors. The low-grade gliomas' first line of treatment is gross total resection. However, when gross total resection is not possible, options for adjuvant therapy are limited. MRI-guided laser ablation (magnetic resonance-guided laser interstitial thermal therapy (MRgLITT)) offers a new option for treatment in selected cases. We present a description of the current MRgLITT technology and an exemplary case-series review of our experience in its use in LGGs.

CASE DESCRIPTION

A 19-month-old male was referred to the pediatric neurosurgery clinic with an incidental left temporal lesion discovered on a prenatal ultrasound. An MRI of the brain revealed a diffuse mesial temporal lesion. Electroencephalogram (EEG) showed generalized activity arising from the lesion. The patient underwent a navigation-guided biopsy then, two bolts were secured to the skull, and laser ablation was performed with intraoperative MR guidance. Pathology was consistent with ganglioglioma. Follow-up images 13 months after ablation showed a significant volumetric reduction in size of the tumor.

DISCUSSION

It is important to achieve maximal resection of low-grade gliomas in children, lessening the need for adjuvant chemotherapy and radiotherapy, while minimizing the length of hospital stay and disruption to the child's life. Of our nine LGGs patients treated with this technology, six had undergone previous surgery and MRgLITT proved itself to be a safe surgical treatment option to achieve further cytoreduction. While most of the cases are pilocytic astrocytomas, the location of the tumors was surgically challenging. Eight of the nine cases required a single trajectory-laser-while our case example requires two lasers. Only a case of a midbrain-thalamic tumor presented a post-ablation significant brain edema as perioperative complication [1]. Eight of the nine tumors did not require any coadjuvant therapy or further surgical treatment to date.

CONCLUSION

MRIgLITT is a successful option for treatment for selected de novo or recurrent low-grade gliomas in children. It can be combined with other therapies offering the advantages of a minimally invasive procedure. LITT may be added to the current pediatric neuro-oncology protocols, but larger prospective series are needed to show the effectiveness of LITT and to standardize indications and protocols.

Near-Infrared Light-Triggered Switchable Nanoparticles for Targeted Chemo/Photothermal Cancer Therapy

Accumulation of nanoparticles in solid tumors depends on their extravasation, but their efficacy is often compromised by intrinsic physiological heterogeneity in tumors. The conventional solutions to circumvent this problem are size control of nanoparticles or increasing the vascular permeability. The aim of this study is to investigate the combination effect of size variation of stimuli-responsive nanoparticles and improved vascular permeability triggered by near-infrared (NIR) light irradiation. Doxorubicin (DOX), a clinically proven drug for bladder cancer, was encapsulated in the nanocomposites with high loading content up to 45%. We show that NIR light-responsive size-switchable nanocarriers could considerably enhance the tumor-targeting of DOX in bladder tumor-bearing mice. Moreover, a combination of NIR-induced hyperthermia and DOX-mediated chemotherapy resulted in remarkable inhibition of tumor growth in mice. Histological results suggest that the change in morphology of tumor microvasculature may account for enhanced extravasation and accumulation of the nanodrugs upon NIR irradiation. Together, these data suggest that external stimuli-responsive drug delivery system offers a safe and effective means of targeted chemo/photothermal therapy.

Present and Future Application of Energy Devices in Thoracic Surgery

In the last decade, many energy devices have entered day-to-day practice in thoracic surgery. Some have proven and recognized applications, whereas others still require further trials. Nevertheless, currently used devices continue to be improved on and new applications for current devices will be evaluated. Ultimately, novel applications of energy in thoracic surgery and refinement in technology will hopefully allow for safer and less invasive techniques for patients requiring thoracic surgical procedures. In this article, we review the present and future applications of energy devices in thoracic surgery.

Current Applications of MRI-Guided Laser Interstitial Thermal Therapy in the Treatment of Brain Neoplasms and Epilepsy: A Radiologic and Neurosurgical Overview

Minimally invasive stereotactic tumor ablation is a viable option for the treatment of benign and malignant intracranial lesions. Although surgical excision constitutes first-line therapy for various brain pathologies, it can cause irreversible neurologic deficits. Additionally, many patients who may benefit from surgery do not qualify as surgical candidates due to multiple comorbidities. Recent advancements in laser interstitial thermal therapy, namely the ability to monitor ablation in real-time under MR imaging, have improved the safety and efficacy of the procedure. MRI-guided laser interstitial thermal therapy is currently used as a minimally invasive treatment for brain metastases, radiation necrosis, glioma, and epilepsy. This article will discuss the principles, suggested indications, complications, and imaging characteristics of MRI-guided laser interstitial thermal therapy as they pertain to the treatment of brain pathology.

The distribution of heat in bone during radiofrequency ablation of an ex vivo bovine model of osteoid osteoma

Osteoid osteoma is treated primarily by radiofrequency (RF) ablation. However, there is little information about the distribution of heat in bone during the procedure and its safety. We constructed a model of osteoid osteoma to assess the distribution of heat in bone and to define the margins of safety for ablation. Cavities were drilled in cadaver bovine bones and filled with a liver homogenate to simulate the tumour matrix. Temperature-sensing probes were placed in the bone in a radial fashion away from the cavities. RF ablation was performed 107 times in tumours < 10 mm in diameter (72 of which were in cortical bone, 35 in cancellous bone), and 41 times in cortical bone with models > 10 mm in diameter. Significantly higher temperatures were found in cancellous bone than in cortical bone (p < 0.05). For lesions up to 10 mm in diameter, in both bone types, the temperature varied directly with the size of the tumour (p < 0.05), and inversely with the distance from it. Tumours of > 10 mm in diameter showed a trend similar to those of smaller lesions. No temperature rise was seen beyond 12 mm from the edge of a cortical tumour of any size. Formulae were developed to predict the expected temperature in the bone during ablation.

Locally ablative non-surgical management of colo-rectal liver metastasis

BACKGROUND

Liver is one of the commonest sites of metastasis in colorectal cancer patients. Solitary liver metastasis or oligometastasis are traditionally treated by surgical resection or chemotherapy.

DISCUSSION

There may be a subgroup of these patients who are not suitable for surgery or chemotherapy due to various co-morbid factors. These patients can be treated by novel minimally invasive or noninvasive ablative techniques like interstitial brachytherapy, extracranial stereotactic radiotherapy, and radiofrequency ablation.

Image-guided percutaneous ablation therapies for local recurrences of thyroid tumors

The incidence of thyroid carcinoma has increased steadily over the last few decades. Most differentiated thyroid carcinomas (DTC) are cured thanks to the initial treatment with surgery and radioiodine therapy. Nevertheless, neck lymph node metastases are found in a few of these patients during their long-term clinical and ultrasound follow-up. In some of these cases radioiodine treatment may not be effective in eradicating nodal metastases due to scant 131-I uptake. Additionally, a few of these patients undergo repeated neck explorations and/or resections. Based on these considerations and on the frequently indolent course of DTC neck metastases, a non-surgical therapeutic approach should be considered to control small local foci of DTC. There is increasing interest in mini-invasive image-guided procedures that can be performed under local anesthesia which do not affect the performance status of the patient. Image-guided minimally invasive ablative therapies delivered by using needle-like applicators include both thermal and non-thermal source techniques. Over the past 25 years, these therapies have gained widespread attention and, in many cases, broad clinical acceptance as methods for treating focal malignancies. In an attempt to overcome the limitations of treating certain unresectable tumor types not amenable to a further surgical treatment, a few investigators have reported successfully combining percutaneous therapies with other oncologic treatment strategies (combined treatments). In this review, we reported mini-invasive techniques more commonly employed in selected cases to ameliorate local compressive symptoms, control hormonal production, and reduce the volume of neoplastic tissue prior to traditional palliative treatment.

Therapeutic efficacy of bipolar radiofrequency thermotherapy for patients with chronic prostatitis: a retrospective analysis of 26 cases

PURPOSE

Chronic prostatitis (CP) does not yet have a universally successful therapy. Alternative treatments including thermotherapy have been adopted in the multimodal management of pain and voiding dysfunction. We retrospectively analyzed the therapeutic efficacy of bipolar radiofrequency thermotherapy for patients who were unsatisfied with conventional medication for CP.

MATERIALS AND METHODS

A retrospective study between October 2009 and September 2010 of 26 patients who were under 50 years old and diagnosed with CP (National Institutes of Health [NIH]-category III) was performed. Twenty patients were diagnosed with inflammatory CP (NIH-category IIIa) and the rest with noninflammatory CP (NIH-category IIIb). We used the Tempro system at an intraprostatic temperature of 55℃ for 50 minutes with a medium heating rate. All patients also completed the NIH-Chronic Prostatitis Symptom Index (CPSI) before and after treatment.

RESULTS

In the patients diagnosed with CP, the mean serum prostate-specific antigen (PSA) level was 0.9±0.3 ng/ml, the prostate volume was 27.1±5.5 g, and the average score for all 3 domains on the NIH-CPSI significantly decreased. The total scores decreased from 19.8±7.1 to 11.1±7.0, the pain domain decreased from 8.6±3.1 to 4.8±3.1, the voiding symptom domain decreased from 5.1±1.8 to 2.9±1.8, and the effect on the quality of life decreased from 6.1±2.2 to 3.4±2.2 (p<0.05).

CONCLUSIONS

Bipolar radiofrequency thermotherapy for patients with CP intractable to conventional medication can provide significant improvement in the NIH-CPSI. Large, randomized controlled trials will also be required to confirm the efficacy of this therapy.

Bimodal electric tissue ablation (BETA) compared with the Cool-Tip RFA system

BACKGROUND

Bimodal electric tissue ablation (BETA) incorporates the process of electrolysis into radiofrequency ablation (RFA) to increase the size of tissue ablation. This study investigated whether BETA could increase the efficacy of the Cool-Tip RF system (Covidien, Boulder, CO, USA) to produce larger ablations. It also investigated whether applying electrolysis only during the pretreatment phase (called electrochemical treatment (ECT)/RFA group) is as effective as BETA (where electrolysis was used during both the pretreatment and RFA phases).

METHODS

A Cool-Tip RF system (Covidien) was used to test three types of ablations (RFA, BETA, and ECT/RFA) in a pig liver model. In BETA, 9 V of direct current was provided for 10 min, after which the RF generator was started and both electrical circuits were allowed to run concurrently. In ECT/RFA, however, the direct current circuit was switched off after 10 min of pretreatment and only RFA was performed as described above. Ablation sizes were measured in three dimensions.

RESULTS

The size of ablations (transverse diameter A and B) produced by BETA and ECT/RFA was significantly larger compared with standard RFA (P < 0/001). BETA also created larger ablations compared with ECT/RFA (P < 0.001).

CONCLUSION

BETA could improve the efficacy of the Cool-Tip RF system (Covidien) to achieve larger ablations. The increased tissue hydration improved delivery of electrical energy to the tissues and delayed the process of desiccation, thus allowing the ablation process to continue for longer periods of time to produce larger ablations. BETA could be used to treat larger liver tumours more effectively than standard RFA.

Synergy in cancer treatment between liposomal chemotherapeutics and thermal ablation

Minimally invasive image-guided tumor ablation using short duration heating via needle-like applicators using energies such as radiofrequency or microwave has seen increasing clinical use to treat focal liver, renal, breast, bone, and lung tumors. Potential benefits of this thermal therapy include reduced morbidity and mortality compared to standard surgical resection and ability to treat non-surgical patients. However, improvements to this technique are required as achieving complete ablation in many cases can be challenging particularly at margins of tumors>3 cm in diameter and adjacent to blood vessels. Thus, one very promising strategy has been to combine thermal tumor ablation with adjuvant nanoparticle-based chemotherapy agents to improve efficiency. Here, we will primarily review principles of thermal ablation to provide a framework for understanding the mechanisms of combination therapy, and review the studies on combination therapy, including presenting preliminary data on the role of such variables as nanoparticle size and thermal dose on improving combination therapy outcome. We will discuss how thermal ablation can also be used to improve overall intratumoral drug accumulation and nanoparticle content release. Finally, in this article we will further describe the appealing off-shoot approach of utilizing thermal ablation techniques not as the primary treatment, but rather, as a means to improve efficiency of intratumoral nanoparticle drug delivery.

Percutaneous radiofrequency ablation of renal parenchyma: experimental study on the optimal temperature and the impact of vasoactive drugs

BACKGROUND AND PURPOSE

Radiofrequency (RF) is an efficient, inexpensive, safe, and friendly option for the management of small renal tumors. The objective was to evaluate the ideal temperature for renal cell destruction in dogs by RF and to verify whether the injection of vasoactive drugs, such as prostaglandin E1 and adrenaline, can help to improve the results, compared with "dry" RF ablation.

MATERIALS AND METHODS

The study was divided into three phases: Initially, 16 dogs of comparable weight underwent RF ablation of the renal parenchyma at temperatures of 80°C, 90°C, and 100°C. After that, seven other dogs received adrenaline (vasoconstrictor) and seven received prostaglandin E1 (vasodilator). Finally, the results from 14 animals were compared with those of the 16 (dry RF) dogs at the optimum temperature found. After 14 days, the animals underwent nephrectomy to evaluate the size of the lesions (width and depth), histology examination, and were then sacrificed.

RESULTS

There were no clinical or surgical complications in any of the dogs, and none died before the 14th day after the procedure. The optimum temperature was found to be 90°C. Prostaglandin E1 resulted in significantly larger lesions (in depth and width) than adrenaline, with lower impedance. Prostaglandin did not increase the lesions compared with dry RF. All the kidneys presented total coagulation necrosis, with no viable cells in the histologic analysis of the treated tissue.

CONCLUSION

In the ablation of renal cells by RF, prostaglandin produced larger lesions (in depth and width) than the same procedure using adrenaline, and its performance was similar to that of RF without injection of drugs.

Hepatic tumor ablation: application in a community hospital setting

Primary liver tumors are a common clinical problem in the United States and worldwide. Resection has historically been used to treat liver lesions. Commonly used liver-directed therapies include transarterial chemoembolization, selective internal radiation therapy, and ablative therapy. Only ablative therapy can cause direct destruction of the targeted tissue. The commercially available modalities in the United States are all based on thermoablative technology. This article examines the various ablative technologies and their application, as well as how these procedures can be performed safely and with optimal outcomes, in a community cancer center.

Ultrasound-Guided, Video-Assisted Transdiaphragmatic Radiofrequency Ablation for Primary Liver Malignancy or Metastatic Nodules

Objective

Percutaneous radiofrequency ablation (RFA) is among the best options in the treatment of primary liver malignancy and metastases because it is a highly effective and minimally invasive alternative to resection in small, nonresectable tumors or in poor surgical candidates and is associated with low morbidity and mortality. We evaluated the clinical feasibility and safety of thoracoscopic, ultrasound (US)-guided RFA of subdiaphragmatic liver malignancies in advanced cirrhotic patients awaiting transplantation.

Methods

Two patients (one female and one male) with end-stage cirrhosis who developed hepatocellular carcinoma were treated thoracoscopically by US-guided RFA. An endoscopic US probe was inserted into the right pleural space through a 10-mm working channel. An RF-operating needle applicator was inserted through a second 10-mm working port after identification of the lesion, penetrating the diaphragm toward the lesion. The procedure duration, applied energy, and generator output were recorded during the intervention. The treatment result and procedure-related complications were analyzed.

Results

The procedure duration was 74 and 92 minutes, respectively. A mean energy deposition of 353 joules resulted in a mean coagulation volume of 115 cm. Tumor ablation was achieved as determined by the postinterventional lack of contrast enhancement in the target region at the follow-up computed tomographic scans performed after 4 months.

Conclusions

RFA offers definite possibilities in the management of small-sized tumors. Thoracoscopic, US-guided transdiaphragmatic RFA has proven to be clinically feasible and safe and can be an effective modality for treating subdiaphragmatic liver lesions. Its minimally invasive nature is the most important advantage compared with surgical resection, especially for patients with high operative risk.

Principles of and advances in percutaneous ablation

Image-guided tumor ablation with both thermal and nonthermal sources has received substantial attention for the treatment of many focal malignancies. Increasing interest has been accompanied by continual advances in energy delivery, application technique, and therapeutic combinations with the intent to improve the efficacy and/or specificity of ablative therapies. This review outlines clinical percutaneous tumor ablation technology, detailing the science, devices, techniques, technical obstacles, current trends, and future goals in percutaneous tumor ablation. Methods such as chemical ablation, cryoablation, high-temperature ablation (radiofrequency, microwave, laser, and ultrasound), and irreversible electroporation will be discussed. Advances in technique will also be covered, including combination therapies, tissue property modulation, and the role of computer modeling for treatment optimization.

Effects of gold nanorod concentration on the depth-related temperature increase during hyperthermic ablation

The photothermal properties of gold nanorods (GNRs) provide an opportunity for the clinical application of highly efficient and tumor-specific photothermal therapy. For the effective hyperthermic ablation of tumor tissue using GNRs, it is essential to maintain a homogeneous therapeutic temperature in the target tissue during treatment. This study investigates whether the concentration of GNRs affects the distribution of the temperature increase during hyperthermal therapy. The investigation is conducted using polyacrylamide phantoms containing varying amounts of GNRs. In 0.1, 0.25, and 0.5 nM GNR-suspended phantoms, the change in temperature is relatively uniform along the depth of each phantom during laser irradiation at 2 W cm(-2) . In 1.0, 2.0, and 5.0 nM GNR-suspended phantoms, the rates of temperature increase in the deep regions of the phantoms decrease with increasing GNR concentration. At a laser irradiation of 5 W cm(-2) , the temperature of the GNR-suspended phantoms increases at a faster rate, whereas the range of GNR concentrations for maintaining the homogeneity of the temperature increase is not affected. This suggests that the concentration of GNRs is the major determinant of the depth-related temperature increase during hyperthermic ablation. Therefore, prior to the clinical application of hyperthermic ablation using GNRs, the concentration of GNRs has to be optimized to ensure a homogeneous distribution of therapeutic temperature in the targeted tissue.

Benign prostatic hyperplasia

This article reviews the epidemiology of benign prostatic hyperplasia (BPH), evaluation of patients with lower urinary tract symptomatology (LUTS), and management of patients with BPH and LUTS. The evaluation includes history and physical examination, laboratory testing, and specialized studies. The management includes medical and surgical options. Medical options include alpha-1-adrenergic receptor blockers, 5alpha-reductase inhibitors, and combinations of these and other medications. Surgical options include endoscopic procedures, open procedures, and laser procedures.

Low dose, alternating electric current inhibits growth of prostate cancer

BACKGROUND

A number of minimally invasive technologies exist for the treatment of prostate cancer (CaP), each with their associated morbidities. We sought to test the efficacy of low dose alternating electric current (LDAEC) to inhibit CaP growth in a preclinical setting and determine its effect on normal tissue.

METHODS

In the first study, two power settings, 15 or 25 mA of current, and two treatment times, 15 or 60 min, were evaluated in C4-2B CaP xenografts. In the second study, power was regulated to maintain an intra-tumoral temperature of <or=45 degrees C in C4-2B and LuCaP 35 tumors. In both studies, tumor volume, serum PSA levels, survival and histology were analyzed. In a third study, LDAEC was applied to mice hamstrings with evaluation of gait and histology.

RESULTS

The most effective tumor volume reduction in the first study was seen with tumors treated with 25 mA for 15 min (62 +/- 9.4% decrease, P = 0.001). Longer treatment time did not enhance treatment effect. Using 45 degrees C to govern delivery of LDAEC resulted in a near 100% reduction in tumor volume in 8/10 mice with C4-2B tumors (P < 0.001) with similar inhibition of LuCaP 35 tumors (P = 0.01). This treatment, although resulting in skeletal muscle necrosis, did not affect nerves, smooth muscle and blood vessels.

CONCLUSION

LDAEC demonstrates efficacy against C4-2B and LuCaP 35 CaP xenografts while causing no harm to nerves and blood vessels. These results warrant further investigations into the use of LDAEC as a treatment for CaP.

Magnetic thermal ablation using ferrofluids: influence of administration mode on biological effect in different porcine tissues

The purpose of this study was to compare the effects of magnetic thermal ablation in different porcine tissues using either a singular injection or a continuous infusion of superparamagnetic iron oxide nanoparticles. In the first setting samples of three ferrofluids containing different amounts of iron (1:171, 2:192, and 3:214 mg/ml) were singularly interstitially injected into specimens of porcine liver, kidney, and muscle (n = 5). Then the specimens were exposed to an alternating magnetic field (2.86 kA/m, 190 kHz) generated by a circular coil for 5 min. In the second experimental setup ferrofluid samples were continuously interstitially infused into the tissue specimens during the exposure to the magnetic field. To measure the temperature increase two fiber-optic temperature probes with a fixed distance of 0.5 cm were inserted into the specimens along the puncture tract of the injection needle and the temperature was measured every 15 s. Finally, the specimens were dissected, the diameters of the created thermal lesions were measured, and the volumes were calculated and compared. Compared to continuous infusion, a single injection of ferrofluids resulted in smaller coagulation volumes in all tissues. Significant differences regarding coagulation volume were found in kidney and muscle specimens. The continuous infusion technique led to more elliptically shaped coagulation volumes due to larger diameters along the puncture tract. Our data show the feasibility of magnetic thermal ablation using either a single interstitial injection or continuous infusion for therapy of lesions in muscle, kidney, and liver. Continuous infusion of ferrofluids results in larger zones of necrosis compared to a single injection technique.

Preoperative prediction of multifocal prostate cancer and application of focal therapy: review 2007

Prostate cancer is a leading malignancy among men. Early prostate cancer is most commonly treated with radical surgery and radiotherapy. In the era of prostate-specific antigen and newly emerging highly specific screening tests, a greater number of men are given a diagnosis earlier in life, and disease is more often confined. Less-invasive treatments, such as focal therapy, are becoming increasingly popular, yielding shorter hospital stays, faster recovery, and fewer complications. Potential drawbacks to focal therapy include the risk of incomplete treatment, which may result from missed cancer foci and inadequate ablation to target tissues. Furthermore, this approach is not universally applicable to all patients--for example, those who have periurethral and extraprostatic extension of the tumor may not benefit from focal treatment. This article reviews the importance of multifocal prostate cancer and the application of focal treatment.

Prostate Tissue Analysis Immediately Following Magnetic Resonance Imaging Guided Transurethral Ultrasound Thermal Therapy

PURPOSE

Preclinical experiments were performed in an acute canine model to analyze the spatial pattern of thermal damage generated in the prostate gland following treatment with a prototype magnetic resonance imaging guided transurethral ultrasound heating system. In particular the boundary of tissue coagulation was analyzed to quantify the treatment margin resulting from this technology.

MATERIALS AND METHODS

A heating device incorporating a planar 20 x 3.5 mm transducer operated at 9.1 MHz was used to deliver ultrasound energy to targeted regions in the prostate gland in 7 animals monitored with magnetic resonance imaging thermometry during heating. The animals were sacrificed approximately 45 minutes after treatment. The thermal damage pattern was evaluated using contrast enhanced magnetic resonance imaging, vital tissue staining, and whole mount hematoxylin and eosin stained histological sections. An image warping technique enabled quantitative comparison of these data.

RESULTS

Regions of thermal fixation, coagulative necrosis and hemorrhage were observed in the treated prostate glands. The extent of the necrotic region was relatively insensitive to vessel cooling effects. Metabolic enzyme functionality coincided with tissue outside of the treatment area. At the edge of the thermal damage pattern the transition from coagulative necrosis to no visible damage occurred within 3 mm or less.

CONCLUSIONS

The narrow extent of the thermal margin suggests that tissue sparing outside of the prostate could be an advantage of this treatment. Histological measurements showed a high level of spatial accuracy, useful for developing accurate control techniques for directional transurethral ultrasound thermal therapy in the treatment of prostate diseases.

Pulsed-high intensity focused ultrasound enhanced tPA mediated thrombolysis in a novel in vivo clot model, a pilot study

INTRODUCTION

Thrombotic disease continues to account for significant morbidity and mortality. Ultrasound energy has been investigated as a potential primary and adjunctive treatment for thrombotic disease. We have previously shown that pulsed-high intensity focused ultrasound (HIFU) enhances thrombolysis induced by tissue plasminogen activator (tPA) in vitro, including describing the non-destructive mechanism by which tPA availability and consequent activity are increased. In this study we aimed to determine if the same effects could be achieved in vivo.

MATERIALS AND METHODS

In this study, pulsed-HIFU exposures combined with tPA boluses were compared to treatment with tPA alone, HIFU alone and control in a novel in vivo clot model. Clots were formed in the rabbit marginal ear vein and verified using venography and infrared imaging. The efficacy of thrombolytic treatment was monitored via high resolution ultrasonography for 5 h post-treatment. The cross-sectional area of clots at 4 points along the vein was measured and normalized to the pre-treatment size.

RESULTS

At 5 h the complete recanalization of clots treated with pulsed-HIFU and tPA was significantly different from the partial recanalization seen with tPA treatment alone. tPA treatment alone showed a significant decrease in clot versus control, where HIFU was not significantly different than control. Histological analysis of the vessel walls in the treated veins showed no apparent irreversible damage to endothelial cells or extravascular tissue.

CONCLUSIONS

This study demonstrates that tPA mediated thrombolysis can be significantly enhanced when combined with non-invasive pulsed-HIFU exposures.

MRI-guided Thermal Ablation Therapy: Model and Parameter Estimates to Predict Cell Death from MR Thermometry Images

Solid tumors and other pathologies can be treated using laser thermal ablation under interventional magnetic resonance imaging (iMRI) guidance. A model was developed to predict cell death from magnetic resonance (MR) thermometry measurements based on the temperature-time history, and validated using in vivo rabbit brain data. To align post-ablation T2-weighted spin-echo MR lesion images to gradient-echo MR images, from which temperature is derived, a registration method was used that aligned fiducials placed near the thermal lesion. The outer boundary of the hyperintense rim in the post-ablation MR lesion image was used as the boundary for cell death, as verified from histology. Model parameters were simultaneously estimated using an iterative optimization algorithm applied to every interesting voxel in 328 images from multiple experiments having various temperature histories. For a necrotic region of 766 voxels across all lesions, the model provided a voxel specificity and sensitivity of 98.1 and 78.5%, respectively. Mislabeled voxels were typically within one voxel from the segmented necrotic boundary with median distances of 0.77 and 0.22 mm for false positives (FP) and false negatives (FN), respectively. As compared to the critical temperature cell death model and the generalized Arrhenius model, our model typically predicted fewer FP and FN. This is good evidence that iMRI temperature maps can be used with our model to predict therapeutic regions in real-time during treatment.

Correlation of contrast-enhanced MR images with the histopathology of minimally invasive thermal and cryoablation cancer treatments in normal dog prostates

Magnetic Resonance Imaging (MRI) is a promising tool for visualizing the delivery of minimally invasive cancer treatments such as high intensity ultrasound (HUS) and cryoablation. We use an acute dog prostate model to correlate lesion histopathology with contrast-enhanced (CE) T1 weighted MR images, to aid the radiologists in real time interpretation of in vivo lesion boundaries and pre-existing lesions. Following thermal or cryo treatments, prostate glands are removed, sliced, stained with the vital dye triphenyl tetrazolium chloride, photographed, fixed and processed in oversized blocks for routine microscopy. Slides are scanned by Trestle Corporation at .32 microns/pixel resolution, the various lesions traced using annotation software, and digital images compared to CE MR images. Histologically, HUS results in discrete lesions characterized by a "heat-fixed" zone, in which glands subjected to the highest temperatures are minimally altered, surrounded by a rim or "transition zone" composed of severely fragmented, necrotic glands, interstitial edema and vascular congestion. The "heat-fixed" zone is non-enhancing on CE MRI while the "transition zone" appears as a bright, enhancing rim. Likewise, the CE MR images for cryo lesions appear similar to thermally induced lesions, yet the histopathology is significantly different. Glands subjected to prolonged freezing appear totally disrupted, coagulated and hemorrhagic, while less intensely frozen glands along the lesion edge are partially fragmented and contain apoptotic cells. In conclusion, thermal and cryo-induced lesions, as well as certain pre-existing lesions (cystic hyperplasia - non-enhancing, chronic prostatitis - enhancing) have particular MRI profiles, useful for treatment and diagnostic purposes.